https://epg.modot.org/api.php?action=feedcontributions&user=Jonesjb&feedformat=atomEngineering_Policy_Guide - User contributions [en]2024-03-29T02:21:54ZUser contributionsMediaWiki 1.33.1https://epg.modot.org/index.php?title=606.1_Guardrail&diff=35034606.1 Guardrail2015-02-04T15:51:18Z<p>Jonesjb: /* 606.1.3.1 3R/4R Projects */ Clarified that guardrail height is measured to the top of the beam.</p>
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<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
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==606.1.1 Types of Guardrail==<br />
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'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
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'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
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'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
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'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
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==606.1.2 Guardrail Terms==<br />
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'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
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'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
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'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
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'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
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|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
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|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
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|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
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|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
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|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
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|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
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|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
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|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
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|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
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'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
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==606.1.3 Applications==<br />
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===606.1.3.1 3R/4R Projects===<br />
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The necessity of guardrail modifications must be evaluated when 3R or 4R work is performed on any state-maintained roadway. Guardrail modifications are not generally evaluated for 1R or 2R work except as outlined in [[:Category:128 Conceptual Studies#128.2 Preventive Maintenance Projects (1R and 2R)|EPG 128.2 Preventive Maintenance Projects (1R and 2R)]].<br />
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* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
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* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
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* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
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* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
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* All existing guardrail not warranted by present standards is to be removed.<br />
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* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
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* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
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:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
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:2. Warranted by an analysis of accident history or,<br />
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:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
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<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
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* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the top of the guardrail beam remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to a 29 in. top height. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
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* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail top height less than 26 ½ in., the top height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
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* Any unconnected or unacceptably connected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
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Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
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On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
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:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
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===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
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Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
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An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
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'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
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'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
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'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system may be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be minimized through grading, the bullnose guardrail system is an appropriate treatment for new construction. This system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.39 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="240px" align="right" <br />
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|<center>'''Additional Information'''</center><br />
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|align="center"|[[751.1 Preliminary Design#Common Bridge Rails (for Rehabilitations)|Common Bridge Rails (for Rehabilitations)]] Table <br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
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Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an crash history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded or the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
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===606.1.3.10 Bridge Piers and Sign Trusses===<br />
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Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
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===606.1.3.11 Signs===<br />
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Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
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===606.1.3.12 Outer Roadways===<br />
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Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
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===606.1.3.13 Headwalls===<br />
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Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
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When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
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===606.1.3.14 Medians===<br />
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Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
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Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
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[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
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===606.1.3.15 Restricted Lateral Clearance===<br />
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When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
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===606.1.3.16 Barricade of Existing Streets and Roads===<br />
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Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
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===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[image:616.1.4.jpg|center|1075px]]<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=750.7_Non-Hydraulic_Considerations&diff=34335750.7 Non-Hydraulic Considerations2014-09-05T19:48:47Z<p>Jonesjb: /* 750.7.2 Types */ Clarified the parameters of Type C pipe use in the 'Permissible Pipe Types by Group' table.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Metal and Concrete Pipe'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri07058/or08014.pdf Report 2008]<br />
|-<br />
|'''High Density Polyethylene (HDPE) Pipe Culverts'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri01037/Brf2002.htm Summary 2002]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri01037/RDT02007.pdf Report 2002]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri01037/Brf2002.pdf Summary 2002]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri01037/RDT02007.htm Report 2002]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
==750.7.1 General==<br />
Drainage structures are located and designed to adequately handle runoff across improvements and to handle runoff from the improvement. Non-Hydraulic Considerations presents criteria pertaining to the selection of culvert and storm sewer material and appurtenances. The hydraulic design of culverts and other drainage facilities is discussed in other articles under [[:Category:750 Hydraulic Analysis|Hydraulic Analysis]].<br />
<br />
==750.7.2 Types==<br />
Permissible culvert pipe types are separated into the following groups.<br />
<br />
<div id="Permissible Pipe Types by Group"></div><br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ '''Permissible Pipe Types by Group'''<br />
! style="background:#BEBEBE"|Group A (ADT>3500) !! style="background:#BEBEBE"| Group B (ADT&le;3500) !! style="background:#BEBEBE"|Group C (ADT<1700)<br />
|-<br />
| Reinforced Concrete || Group A Pipe || Group A Pipe<br />
|-<br />
| Vitrified Clay || Polypropylene || Group B Pipe<br />
|-<br />
| Aluminum Coated Steel || High Density Polyethylene || Zinc-Coated Steel<br />
|-<br />
| Polymer Coated Steel|| Steel Reinforced Polyethylene || Bituminous-Coated Steel<br />
|-<br />
| Aluminum Alloy || Polyvinyl chloride || rowspan="5" |<br />
|-<br />
| Polypropylene &le;36 in. || rowspan="4" |<br />
|-<br />
| High Density Polyethylene &le;24 in.<br />
|-<br />
| Steel Reinforced Polyethylene &le;24 in.<br />
|-<br />
| Polyvinyl chloride &le;36 in.<br />
|}<br />
<br />
In general, a group of permissible culvert types, dependent upon the design ADT, is specified as described in succeeding sections. For special situations, a qualified pipe group may be specified, as described in [[#750.7.2.5 Installations for Special Situations|Installations for Special Situations]]. The final selection of the structure type is based on requirements in the standard specifications, on good engineering judgment, and economy with consideration of service and maintenance costs.<br />
<br />
===750.7.2.1 Roadways with ADT > 3500===<br />
For roadways with ADT > 3500, Group A pipe will be specified for crossroad structures. The hydraulic design computations for Group A pipe should be performed for both corrugated and smooth wall pipe. At each pipe location on the plans, both the corrugated and equivalent smooth wall diameters should be shown, as in the following example.<br />
<br />
:::36" Group A Pipe (30")<br />
:::36" Group A Pipe (36")<br />
<br />
The first number shown represents the corrugated diameter and is the value used for the pay item, while the number shown in parenthesis is the equivalent smooth wall pipe diameter. The latter must be shown whether the size is equal to or less than the corrugated size.<br />
<br />
The following exceptions apply to the use of Group A pipe:<br />
<br />
*Reinforced concrete box culverts are specified when it is more economical to build the reinforced box culvert than it is to provide an equivalent pipe culvert.<br />
*Vitrified clay pipe (extra strength) is specified when the purpose of the culvert is a sanitary sewer.<br />
*Group C pipe should be specified for the portion of median outlet pipes outside the edge of pavement where such pipes are located on high fills requiring a break in flowline grade. Details for such installations are illustrated in [[Media:750.7 Pipe Grades For Median Drop Inlets.pdf|Pipe Grades For Median Drop Inlets]].<br />
*Group B pipe is specified to drain drop inlets into crossroad drainage structures when such installation necessitates a steep flowline grade and when the pipe will not extend under the pavement or in other non-traffic areas, such as behind guardrail at median piers.<br />
<br />
Pipes of 12 in. and 15 in. are not used except as outlets from drop inlets and in storm sewer systems.<br />
<br />
The requirements for using reinforced concrete pipe or vitrified clay pipe for structures may be waived if conditions warrant, such as poor structure foundation conditions, high fills, simplification of handling traffic, etc.<br />
<br />
===750.7.2.2 Roadways with ADT &le; 3500===<br />
For roadways with ADT &le; 3500, Group B pipe should be specified according to the method used for Group A.<br />
<br />
Some exceptions to specifying Group B on the plans are the following:<br />
<br />
*Reinforced concrete box culverts should be considered for pipes larger than 60 in. diameter.<br />
*Reinforced concrete pipe, corrugated polyethylene pipe or polyvinyl chloride pipe should be specified for locations where high acidity or alkalinity of soils or waters or other abrasive or corrosive elements are present.<br />
*Corrugated metallic-coated steel pipe-arch structures in sizes B-5 and larger may be specified where necessary because of limited allowable structure height. A battery of round pipes or a single elliptical reinforced concrete pipe may be considered in lieu of B-1 through B-4 corrugated metallic-coated steel pipe-arch structures.<br />
*Elliptical reinforced concrete pipe may be specified in special cases, usually for storm sewers, where necessary because of limited allowable structure height.<br />
<br />
Pipes of 12 in. and 15 in. are not used for crossroad culverts, except where the use of an 18 in. pipe will create an unsightly or impracticable drainage condition.<br />
<br />
Corrugated polyethylene pipe (Type S) and polyvinyl chloride pipe are double walled, full circular cross section pipes, with an outer corrugated wall and a smooth inner liner. Only 12 to 60 in. diameter sizes of corrugated polyethylene, or 12 to 48 in. diameter sizes of PVC pipe, are approved for use on highway projects. Corrugations may be either annular or helical. Headwall protection is provided by means of a beveled pipe end treatment, safety slope end section, or metal or concrete flared end sections. [http://modot.mo.gov/business/standards_and_specs/Sec0730.pdf Section 730] of the Standard Specifications require all PVC pipes to have an end section of one of the other Group B pipe materials to protect from ultraviolet degradation where the end of the pipe is exposed.<br />
<br />
===750.7.2.3 Roadways and Roadside Applications with ADT < 1700===<br />
For roadways, side roads, and entrances with ADT < 1700 Group C pipe should be specified according to the methods used for Groups A and B. For information regarding replacement of failed driveway drainage pipes see [[:Category:941 Permits and Access Requests#941.9.8 Maintenance of Residential, Commercial, and Public Road Entrances|EPG 941.9.8 Maintenance of Residential, Commercial and Public Road Entrances]].<br />
<br />
===750.7.2.4 Other Roadway Drainage Structures===<br />
Outer roadway drainage structures shall be selected by ADT as described above. Continuous drainage structures extending under outer roadways are designed to the same standard as required for the portion of the structure under the main roadway. Since a continuous drainage structure usually increases the standard for the portion under the outer roadway, it is usually more economical to use independent structures. Where continuous structures are used, the runoff between the outer roadway and the main roadway is usually carried into the crossroad structure by drop inlets and pipe. Where the crossroad structure is a relatively small pipe, the drop inlet is constructed in the crossroad structure.<br />
<br />
For drainage applications other than crossroad pipes, such as entrances, side roads and median drainage, Group C pipe may be specified.<br />
<br />
Flared end sections or beveled pipe end treatment are specified at both ends of pipe structures 66 in. or less in diameter. In special cases where low clearance exists and the structure is essentially at right angles on roads with less than 400 ADT, pipe arches with flared end sections may be specified.<br />
<br />
===750.7.2.5 Installations for Special Situations===<br />
For installations on a project which normally would require a pipe group option, special conditions may exist which would justify the specifying of a qualified pipe group type. Justification for the selection of a qualified group pipe type include, but are not limited to, unstable foundation, high embankments, high erosive forces, highly abrasive or corrosive conditions, high fire hazard or other pertinent reasons. When any one or a combination of these factors exist, the culvert pipe type(s) best suited to resist such destructive forces is selected and specified by excluding pipe types from a specified group with a note on the plans or Job Special Provision. When a qualified pipe group is specified, the reasons for such selection are included in the letter of transmittal of the plans.<br />
<br />
===750.7.2.6 Storm Sewers===<br />
The permissible storm sewer type under the paved portion and any planned widening of roadways with ADT greater than 3500 is Group A pipe. All other applications of storm sewer are Group B pipe. The standard specifications require that corrugated metal culvert pipes used for storm sewer be smooth interior pipe types, so that consistent hydraulic characteristics may be assumed during design of the entire interconnected system.<br />
<br />
===750.7.2.7 Multiple Opening Installations===<br />
Multiple opening structures, either boxes or pipes, are used as required where the allowable structure height is restricted or to meet [[750.2 Culverts|hydraulic design]] or [[#750.7.3 Environmental Requirements|environmental requirements]]. Where multiple pipes are constructed, the pipes are separated by a distance of 1/2 their outside diameter, or a minimum of 1 ft., whichever is greater. [[#750.7.4.3 Summary of Responsibilities|Analysis, design and final plans preparation responsibility]] for multiple cell box culverts is based on several factors including drainage area. <br />
<br />
===750.7.2.8 Temporary Installations===<br />
For bypasses, crossovers or other temporary installations, regardless of design ADT, Group C pipe should be specified using the same method as for corrugated and smooth wall Group B pipe as explained in [[#750.7.2.2 Roadways with ADT ≤ 3500|Roadways with ADT ≤ 3500]].<br />
<br />
==750.7.3 Environmental Requirements==<br />
<br />
[http://epg.modot.org/index.php?title=127.4_Wetlands_and_Streams#127.4.1.1__Overview Waters of the United States] are under the jurisdiction of the U.S. Army Corps of Engineers (COE) which has implemented a [http://www.nwk.usace.army.mil/Portals/29/docs/regulatory/nationwidepermits/2012/MORC1Streams.pdf Regional Condition] , affecting new and replacement culverts, to [[127.4 Wetlands and Streams|Section 404 Nationwide Permits]] ( all Nationwide Permits including NWP 14, Linear Transportation Projects and NWP 3, Maintenance Activities) for Missouri. <br />
<br />
As part of the regional condition, new and replacement culverts with an inside width/diameter greater than 4 ft. are required to have the invert of the culvert embedded a minimum of 1 ft. below the natural stream bottom. For culverts with an inside width/diameter of 4 ft. or less the invert of the culvert is required to be placed at a depth below or flush with the natural stream bottom. In streams with non-erodible beds the invert of the culvert shall be flush with the natural stream bottom. The embedded area shall be allowed to naturally backfill and shall not be included as part of the flow area for hydraulic design calculations. The regional condition encourages the use of single culverts. If multiple culverts are used, all must be embedded if they meet the width/diameter criteria.<br />
<br />
Also as part of the regional condition, new and replacement culverts are required to convey the geomorphic bankfull discharge (return period of 1.01 – 1.7 years) with an average velocity within the culvert similar to upstream and downstream velocities.<br />
<br />
Bankfull discharge is considered to be the channel forming discharge. Bankfull discharge can be determined from the bankfull stage of the natural stream using HEC-RAS or a channel analysis program such as Valley Section.<br />
<br />
Bankfull stage is the elevation where water begins to overflow on the floodplain. On entrenched or incised streams, bankfull stage is more difficult to determine and is generally associated with a bench or change in slope of the stream bank. Examples of bankfull stage and area are shown in the illustrations below. Other indicators such as a change in vegetation type, particle size of bank material or elevation of bank undercuts can be used to help determine the bankfull stage. For more information on bankfull stage and bankfull indicators, see [http://www.stream.fs.fed.us/publications/PDFs/RM245E.PDF USDA General Technical Report RM-245]. <br />
<br />
The bankfull discharge should not be greater than the discharge associated with a 2 year return period and the bankfull stage should not be above ordinary high water.<br />
<br />
[[Image:750.7.3.jpg|center|775px]]<br />
<br />
Once the bankfull stage has been determined the bankfull area and discharge can be used to determine the minimum width/diameter of the culvert. The Regional Condition provides guidance for the following [http://epg.modot.org/index.php?title=127.4_Wetlands_and_Streams#127.4.1.1__Overview regulated stream types]:<br />
<br />
:1) Perennial streams: Culvert flow area at bankfull stage shall be similar (approximate minimum of 85% of bankfull area) to upstream and downstream preconstruction bankfull area.<br />
<br />
:2) Intermittent streams: Culvert flow area at bankfull stage shall be similar (approximate minimum of 50% of bankfull area) to upstream and downstream preconstruction bankfull area.<br />
<br />
:3) Ephemeral streams: Culvert shall be sized to convey bankfull discharge.<br />
<br />
After the minimum culvert flow area is determined and all other hydraulic design criteria has been met, the average velocity within the final culvert at bankfull discharge shall be checked to ensure that it is similar to the velocities upstream and downstream of the culvert. The Regional Condition does not define similar for these velocities. Engineering judgment should be used to determine what the allowable velocity should be, but generally a 20% or less increase in velocity can be considered to be similar.<br />
<br />
==750.7.4 Box Culverts==<br />
{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="320px" align="right" <br />
|-<br />
|align="center"|'''Additional Info for the Districts'''<br />
|-<br />
|The Bridge Division has prepared the [[media:751.8 Reference Guide SBC Oct 2010.doc|Reference Guide SBC]] for laying out and plan reporting details of concrete single box culverts (SBC) using the standard plans.<br />
|}<br />
<br />
===750.7.4.1 Standard Plans===<br />
HL-93 design loading is used for all culverts, including those located in commercial zones, at major river crossings and on NHS routes. All box culverts shown in the standard plans are valid for 1 ft. thru 50 ft. [[#750.7.11.2 Design Fill Heights|design fill heights]]. <br />
<center><br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ '''Index to Box Culvert Standard Plans'''<br />
! colspan="2" style="background:#BEBEBE"|General Details<br />
|-<br />
|Wing J-bars & Wing Backfill Slopes ||width="100"|[http://www.modot.org/business/standards_and_specs/documents/70337.pdf 703.37]<br />
|-<br />
|Cutting Details for Partial Removal ||[http://www.modot.org/business/standards_and_specs/documents/70338.pdf 703.38]<br />
|-<br />
|Pipe Inlets ||[http://www.modot.org/business/standards_and_specs/documents/70360.pdf 703.60]<br />
|-<br />
|Bar Supports for Concrete ||[http://www.modot.org/business/standards_and_specs/documents/70635.pdf 706.35]<br />
|}<br />
<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ <br />
! style="background:#BEBEBE"|Culvert Details||style="background:#BEBEBE"| Single Barrel||style="background:#BEBEBE"| Double Barrel|| style="background:#BEBEBE"| Triple Barrel<br />
|-<br />
|Square - Straight Wings||[http://www.modot.org/business/standards_and_specs/documents/70310.pdf 703.10] || [http://www.modot.org/business/standards_and_specs/documents/70340.pdf 703.40] ||[http://www.modot.org/business/standards_and_specs/documents/70380.pdf 703.80]<br />
|-<br />
|Square - Flared Wings ||[http://www.modot.org/business/standards_and_specs/documents/70311.pdf 703.11] ||[http://www.modot.org/business/standards_and_specs/documents/70341.pdf 703.41] ||[http://www.modot.org/business/standards_and_specs/documents/70381.pdf 703.81] <br />
|-<br />
|Left Ahead - Straight Wings ||[http://www.modot.org/business/standards_and_specs/documents/70312.pdf 703.12] || [http://www.modot.org/business/standards_and_specs/documents/70342.pdf 703.42] ||[http://www.modot.org/business/standards_and_specs/documents/70382.pdf 703.82]<br />
|-<br />
|Left Ahead - Flared Wings ||[http://www.modot.org/business/standards_and_specs/documents/70313.pdf 703.13] ||[http://www.modot.org/business/standards_and_specs/documents/70343.pdf 703.43] ||[http://www.modot.org/business/standards_and_specs/documents/70383.pdf 703.83]<br />
|-<br />
|Right Ahead - Straight Wings ||[http://www.modot.org/business/standards_and_specs/documents/70314.pdf 703.14] ||[http://www.modot.org/business/standards_and_specs/documents/70344.pdf 703.44] || [http://www.modot.org/business/standards_and_specs/documents/70384.pdf 703.84] <br />
|-<br />
|Right Ahead - Flared Wings ||[http://www.modot.org/business/standards_and_specs/documents/70315.pdf 703.15] ||[http://www.modot.org/business/standards_and_specs/documents/70345.pdf 703.45] ||[http://www.modot.org/business/standards_and_specs/documents/70385.pdf 703.85]<br />
|-<br />
|Cut Sections ||[http://www.modot.org/business/standards_and_specs/documents/70316.pdf 703.16] ||[http://www.modot.org/business/standards_and_specs/documents/70346.pdf 703.46] ||[http://www.modot.org/business/standards_and_specs/documents/70386.pdf 703.86]<br />
|-<br />
|Member Size & Reinforcement Tables ||[http://www.modot.org/business/standards_and_specs/documents/70317.pdf 703.17] ||[http://www.modot.org/business/standards_and_specs/documents/70347.pdf 703.47] ||[http://www.modot.org/business/standards_and_specs/documents/70387.pdf 703.87]<br />
|}<br />
<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ '''Standard Box Culvert Sizes'''<br />
! style="background:#BEBEBE" colspan="2"| !!colspan="14" width="650"|Span (ft.)!!style="background:#BEBEBE" | <br />
|-<br />
!style="background:#BEBEBE" colspan="2"| !! 3!! 4!!5!! 6!!7!!8!!9!!10!!11!!12!!13!!14!!15!!16!! style="background:#BEBEBE"| <br />
|-<br />
|rowspan="15"|'''Height<br/>(ft.)''' ||'''2'''|| X|| X||style="background:#BEBEBE" colspan="12"| ||'''2'''<br />
|-<br />
| '''3'''|| X|| X|| X|| X||style="background:#BEBEBE" colspan="10"| || ''' 3'''<br />
|-<br />
| '''4'''|| X|| X|| X|| X|| X|| X||style="background:#BEBEBE" colspan="8"| || '''4'''<br />
|-<br />
|'''5'''|| X||X||X||X||X||X||X||X||style="background:#BEBEBE" colspan="6"| ||'''5'''<br />
|-<br />
|'''6'''||'''A'''||X||X||X|| X||X||X||X||X|| X||style="background:#BEBEBE" colspan="4"| || '''6'''<br />
|-<br />
|'''7'''||style="background:#BEBEBE"| ||X||X||X||X||X||X||X||X||X||X||X||style="background:#BEBEBE" colspan="2"| || '''7'''<br />
|-<br />
|'''8'''||style="background:#BEBEBE" colspan="2"| ||X||X||X||X||X||X||X||X||X||X||X||X||'''8'''<br />
|-<br />
|'''9'''||style="background:#BEBEBE" colspan="3"| ||X||X||X||X||X||X||X||X||X||X||X|| '''9'''<br />
|-<br />
|'''10'''||style="background:#BEBEBE" colspan="4"| || X||X||X||X||X||X||X||X||X||X|| '''10'''<br />
|-<br />
|'''11'''||style="background:#BEBEBE" colspan="5"| || X||X||X||X||X||X||X||X||X|| '''11'''<br />
|-<br />
|'''12'''|| style="background:#BEBEBE" colspan="6"| ||X||X||X||X||X||X||X||X|| '''12'''<br />
|-<br />
|'''13'''|| style="background:#BEBEBE" colspan="7"| ||X||X||X||X||X||X||X|| '''13'''<br />
|-<br />
|'''14'''|| style="background:#BEBEBE" colspan="8"| ||X||X||X||X||X||X|| '''14'''<br />
|-<br />
|'''15'''|| style="background:#BEBEBE" colspan="9"| ||X||X||X||X||X|| '''15'''<br />
|-<br />
|'''16'''|| style="background:#BEBEBE" colspan="10"| || X||X||X||X|| '''16'''<br />
|-<br />
!style="background:#BEBEBE" colspan="2"| !!3!!4!!5!!6!!7!!8!!9!!10!!11!!12!!13!!14!!15!!16!!style="background:#BEBEBE"| <br />
|-<br />
|colspan="17" align="left"| '''X''' = single, double and triple barrel<br />
|-<br />
|colspan="17" align="left"| '''A''' = double and triple barrel only<br />
|}<br />
<br />
</center><br />
===750.7.4.2 Abrasion of Interior Surfaces===<br />
<br />
The Core Team shall determine whether abrasion of the interior surfaces of the box culvert from large rocks or boulders is likely. If abrasion is to be considered, a structural design performed by the Bridge Division will be required. For guidance in determining when abrasion should be considered in culvert design, refer to the following documents: <br />
<br />
:• Schall, J.T., etal., 2012 ''Hydraulic Design of Highway Culverts – Hydraulic Design Series No. 5 (HDS-5)'', Federal Highway Administration, Publication No. FHWA-HIF-0112-026<br />
<br />
:• NRC. 1978. “Durability of Drainage Pipe.” ''NCHRP Synthesis of Highway Practice No. 50''. Transportation Research Board, National Research Council, Washington, DC, p. 37. <br />
<br />
<br />
===750.7.4.3 Summary of Responsibilities===<br />
<center><br />
<div id="Responsibilities for Multiple Opening Installations"></div><br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ '''Responsibilities for Box Culvert'''<br />
! rowspan="2" style="background:#BEBEBE"|Drainage Area (Acres) !! rowspan="2" style="background:#BEBEBE"| Number of Cells !! rowspan="2" style="background:#BEBEBE"| Design Fill in Standard Plans !! colspan="2" style="background:#BEBEBE"| Responsible Entity !! rowspan="2" style="background:#BEBEBE"| Bridge Number !! rowspan="2" style="background:#BEBEBE"| Pay Items, Job Specials, Estimate<br />
|-<br />
! style="background:#BEBEBE"| Hydraulics !! style="background:#BEBEBE"| Final Plans <br />
|-<br />
| <1000 || 1 || Yes || District || District* || No || Roadway<br />
|-<br />
| <1000 || 1 || No || District || Bridge Division** || No || Roadway<br />
|-<br />
| <1000 || 2 or 3 || N/A || District || Bridge Division || Yes || Bridge<br />
|-<br />
| >1000 || 1, 2 or 3 || N/A || Bridge Division || Bridge Division || Yes || Bridge<br />
|-<br />
| colspan="7" align="left"| * Bridge Division will produce a typical section for the district to use in roadway plans (including quantities per foot) when abrasion design is required<br />
|-<br />
| colspan="7" align="left"| ** Bridge Division will produce a typical section for the district to use in roadway plans (including quantities per foot)<br />
|}<br />
</center><br />
<br />
For drainage areas of 1000 acres and less which require a structure designed by Bridge Division (multiple cell box, etc.), the district shall make the necessary hydraulic analysis and provide the following information to Bridge Division for each structure for placement on the plans:<br />
<br />
:* [[#750.7.4.4 Size|Box Culvert Size]]<br />
:* Drainage Area<br />
:* [http://epg.modot.org/index.php?title=Category:749_Hydrologic_Analysis#749.2.2_Base_Flood Base Flood], discharge and [[748.4 Headwater and Backwater|backwater]] elevation and culvert outlet velocity.<br />
:* [[748.6 High Water Surface Elevation|Design High Water]] elevation, [http://epg.modot.org/index.php?title=Category:749_Hydrologic_Analysis#749.2.1_Design_Frequency_Criteria Design Frequency] and discharge.<br />
:* [[748.2 Roadway Design Criteria|Roadway Design Frequency]] elevation and the [http://epg.modot.org/index.php?title=748.2_Roadway_Design_Criteria#748.2.3_Overtopping_Flood Overtopping Flood] discharge and frequency.<br />
<br />
Multiple cell box structures for drainage areas of 1000 acres and under require that the final plans be done by Bridge Division. Where such plans are required, [http://wwwi/intranet/br/default.htm Bridge Division] shall be furnished with the grade across the structure, typical section, and any other necessary information.<br />
<br />
===750.7.4.4 Size===<br />
<br />
Hydraulic and environmental factors will control the required size of the box culvert. The size of the box culvert will affect the fill slopes and the culvert length. In special cases, a more economical box culvert may be attained by increasing the height of the culvert opening. Box culvert sizes are indicated on the plans as "(span) x (height)". <br />
<br />
===750.7.4.5 Guardrail Attachment===<br />
<br />
When guardrail is provided over a box culvert and the fill over the culvert provides less than 3’ 8” embedment of guardrail posts, guardrail attachments to the culvert shall be provided unless one of the following applies: <br />
<br />
:1) No guardrail required if [[231.2 Clear Zones|clear zones]] are provided.<br />
:2) For smaller box culverts a long span guardrail system as shown in [http://www.modot.org/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] may be used to eliminate posts over the culvert.<br />
<br />
Guardrail posts attached to the top slab of the culvert shall have at least a 10” distance between the face of the headwall and the center of the guardrail post. <br />
<br />
==750.7.5 Pipe Headwalls==<br />
Type S pipe headwalls may be used in lieu of drop inlets for median pipes for medians 60 ft. wide or wider. Details for Type S pipe headwalls are shown on [http://modot.mo.gov/business/standards_and_specs/documents/60405.pdf Standard Plan 604.05].<br />
<br />
==750.7.6 End Treatment==<br />
End treatments on culverts provide safety benefits for errant vehicles, improved structural support for pipe ends, and improved hydraulic flow for pipe entrances. All pipe ends in the clear zone require some type of end treatment. Outside of the clear zone, considerations of hydraulics, aesthetics or soil erosion may warrant the use of an end section.<br />
<br />
The following table contains minimum usage of end treatments as discussed in the ''Roadside Design Guide''. This table and the following discussion should be used with site specific factors, including maintenance concerns, to determine the safe and cost-effective end treatment for each culvert. The ''Roadside Design Guide'' (Chapter 3) has additional discussion of cross-drainage and parallel drainage structures. <br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ '''End Section Requirements'''<br />
! colspan="4" style="background:#BEBEBE"|Within Clear Zone !! style="background:#BEBEBE" width="250"| Outside Clear Zone <br />
|-<br />
| colspan="2" | <center>Crossroad Culverts</center>|| colspan="2" | <center>Parallel Culverts</center>|| rowspan="4" | <center>Permissible to have no end treatment; consider FES or BET especially for ADT &ge; 400</center><br />
|-<br />
| <center>Single Pipes</center> || <center>Multiple Pipes</center> || <center>Single Pipes</center> || <center>Multiple Pipes</center> || <br />
|-<br />
| <center>&le; 36 in. diameter use BET or FES</center>|| <center>&le; 30 in. diameter use BET or FES</center>|| <center>&le; 24 in. diameter BET or FES</center>|| rowspan="2" | <center>Consider SSES for &nbsp; &nbsp; &nbsp; &le; 24 in. diameter</center> || <br />
|-<br />
| <center>> 36 in. diameter use SSES</center> || <center>> 30 in. diameter use SSES</center> || <center>> 24 in. diameter use SSES</center> || ||<br />
|-<br />
| colspan="5" | FES = Flared End Section<br/>BET = Beveled Pipe End Treatment<br/>SSES = Safety Slope End Section<br />
|}<br />
<br />
===750.7.6.1 Flared End Sections===<br />
Flared end sections may be used on concrete, metal, or plastic pipes as shown on [http://modot.mo.gov/business/standards_and_specs/documents/73200.pdf Standard Plan 732.00]. Where flared end sections are used on skewed pipe, the section is placed on the same line as the pipe and the fill slope is warped to fit.<br />
<br />
===750.7.6.2 Beveled Pipe End Treatment===<br />
Beveled pipe end treatment may be used on either corrugated metal or plastic pipes as shown on [http://modot.mo.gov/business/standards_and_specs/documents/73205.pdf Standard Plan 732.05]. All beveled pipes use encasement. Corrugated steel pipe-arches are not beveled. In general, the bevel should not be flatter than 1V:6H nor should the skew exceed 15 degrees. If these controls are exceeded, special consideration is given to the use of headwalls, riprap, or slope pavement to stiffen the structure against uneven loading from the embankment and the dynamic forces of the water. Proposed designs for these conditions are submitted to the Support Center for approval.<br />
<br />
===750.7.6.3 Safety Slope End Sections===<br />
Safety slope end sections are used to reduce the potential for vehicle snagging. End sections with two types of safety treatment for 1V:4H, 1V:6H and 1V:10H slopes are shown in [http://modot.mo.gov/business/standards_and_specs/documents/73210.pdf Standard Plan 732.10]. The 2B (Summary of Quantities) sheet should indicate the slope of the end section and whether the end section is for a crossroad or parallel drainage structure.<br />
<br />
===750.7.6.4 Floodgates===<br />
Floodgates are specified for the outlet ends of pipes where required to prevent floodwater from backing through the pipe. Type 1 floodgates are specified for concrete pipes. Floodgates for concrete box structures will require a special item number and special provision. Type 2 floodgates are specified on corrugated metal pipes. The hydraulic head should be specified on the plans. If the hydraulic head is not specified on the plans, the height of fill above the pipe will be considered the hydraulic head. The number of floodgates is listed on the plans in accordance with pipe sizes.<br />
<br />
For information maintenance of floodgates, see [[614.5 Maintenance of Floodgates|EPG 614.5 Maintenance of Floodgates]].<br />
<br />
==750.7.7 Circular Reinforced Concrete Pipes==<br />
===750.7.7.1 Classes of Strength===<br />
Reinforced concrete pipe is available as any one of five classes designated as Class I, II, III, IV or V. Class V pipe is the strongest design.<br />
<br />
===750.7.7.2 Use of Various Classes===<br />
Class I and II pipes are used only for sewers in trenches outside roadbed and street limits. Class I pipe is provided in 60 to 108 in. diameters, inclusive, and is used with fill 12 ft. or less in depth. Class II and III pipes are provided in sizes from 12 in. to 108 in. diameters, inclusive. Class II pipe is used with fill 15 ft. or less in depth and Class III pipe is used with fill 21 ft. or less in depth. Class IV pipe is provided in 12 in. to 84 in. Diameters, inclusive, and is used with fill 33 ft. or less in depth. Class V pipe is provided in sizes from 12 in. to 72 in. diameters, inclusive, and is used with fill 51 ft. or less in depth. <br />
<br />
===750.7.7.3 Selection of Pipe Class and Installation Type===<br />
In order for the contractor to select the most economical class of reinforced concrete pipe, the fill height must be shown on the culvert sheets. As shown on [http://modot.mo.gov/business/standards_and_specs/documents/72630.pdf Standard Plan 726.30], a range of installation types can be used for each soil category; however, the proper installation type will correspond to the most economical, lowest class of pipe for a given fill height.<br />
<br />
===750.7.7.4 Special Design Reinforced Concrete Pipe===<br />
<br />
Since pipes are specified by group, there is no need for the designer to select a special pipe design. Rather, the responsibility lies with the choices made by the contractor on the job. If the contractor elects to use reinforced concrete pipe, and the fill height exceeds 51 ft., a special design reinforced pipe may be specified for diameters 36 in. or less. [http://www.modot.mo.gov/business/standards_and_specs/Sec1026.pdf Sec 1026] requires the manufacturer, prior to pipe fabrication, to provide design and installation details that must be reviewed by the Bridge Division for compliance with appropriate design standards.<br />
<br />
Special design reinforced concrete pipe shall not be used when fill height exceeds 51 ft. with diameters greater than 36 in. This limit is due to installation difficulties associated with larger pipe diameters with the potential for problems increasing under deep fills.<br />
<br />
===750.7.7.5 Payment for Bedding===<br />
There is no direct payment or [http://www.modot.mo.gov/business/contractor_resources/biditemslisting.htm bid item] for any bedding category; however, when an unsuitable bedding material exists, such as rock, payment for a specific bedding material needed for the installation type specified will be included in the Class 3 excavation.<br />
<br />
==750.7.8 Fill Settlements==<br />
Fill settlements can seriously affect concrete box structures by opening joints and cracks sufficiently to allow the fill around the culvert to infiltrate into the culvert, thereby creating voids which can cause the roadbed to fail. In areas subject to large settlements, other structure types are considered or the box culvert is designed to withstand the settlement. This requires special box culvert designs and where box culverts are to be so designed, [http://wwwi/intranet/br/default.htm Bridge Division] is furnished with full information, including culvert sections, grades, and anticipated settlement. Box culverts with special collars around joints have been successfully designed and used in areas subject to large fill settlements. Since such structures are expensive, it is sometimes more economical to use other structure types, such as flexible pipe.<br />
<br />
==750.7.9 Camber in Culverts==<br />
Camber, as used in culvert design, is defined as the distance the central portion of crossroad structures is constructed above final flowline grade to compensate for anticipated settlement. Typical details for cambering culverts are shown on [http://modot.mo.gov/business/standards_and_specs/documents/72630.pdf Standard Plan 726.30]. A structure designed with proper camber will settle to near flowline grade and elevation when it reaches final settlement. All culverts, except those on non-yielding foundations, are cambered at a minimum rate of 0.01 ft/ft of overfill. Cambers of 0.1 ft. or less are not shown on plans. Where the fill settlement is known, culverts are designed with a camber equal to the anticipated settlement. The camber is shown on the culvert section at the roadbed shoulders by amount and flowline elevation.<br />
<br />
==750.7.10 Culvert Extensions==<br />
All culvert extensions, both boxes and pipes, are extended with structures meeting current design requirements and standards, regardless of the type of standard of the existing structure. Pipe collars, as detailed on [http://modot.mo.gov/business/standards_and_specs/documents/60440.pdf Standard Plan 604.40], are used to connect different types of pipe, and concrete pipe to concrete pipe. For extension of box culverts [http://epg.modot.org/index.php?title=751.8_LRFD_Concrete_Box_Culverts#751.8.3.4_Miscellaneous EPG 751.8.3.4 Miscellaneous, Culvert Extensions]. Additional fills on existing box culverts may require a structural analysis of the existing structure by the Bridge Division. If so, [http://wwwi/intranet/br/default.htm Bridge Division] is furnished a print of the completed culvert section and the standard to which the existing structure was designed, if known, for their use in making the analysis.<br />
<br />
The unit cost for pipe or box extensions is typically greater than the unit cost for new construction of pipe or box culverts.<br />
<br />
For floodplain development permit requirements, see [[748.9 National Flood Insurance Program (NFIP)#748.9.3.3 Culvert Extensions|EPG 748.9.3.3 National Flood Insurance Program (NFIP) - Culvert Extensions]] for structures designed by Bridge or [[127.9 Floodplain Management and the Regulatory Floodway|EPG 127.9 Floodplain Management and the Regulatory Floodway]] for roadway culverts.<br />
<br />
==750.7.11 Overfill Heights==<br />
===750.7.11.1 Minimum Fill Heights===<br />
The minimum allowable fill or cover for all structures is 1 ft. at the outside shoulder line, (refer to [[751.1 Preliminary Design#751.1.2.6.3.3 Roadway Fill|EPG 751.2.6.3.3 Box Culverts, Roadway Fill]] for details of warping fill over exposed portions of box culverts), with the following exceptions:<br />
<br />
*The minimum fill for structural-plate pipe structures is tabulated in [[Media:750.7 Overfill Structural Plate Pipe.pdf|Allowable Overfills for Structural Plate Pipe]].<br />
<br />
* The minimum clearance from the top of pipe structures to the bottom of the aggregate base material is 6 inches.<br />
<br />
* The minimum fill for box culverts at the outside shoulder line is the greater of 1 ft. or the pavement thickness plus 4 ½ in. of aggregate base material, with a minimum of 4 ½ in. of aggregate base material under all pavement. Exceptions are special box culverts designed to carry traffic on the top slab.<br />
<br />
*For roadways with an ADT &le; 1700, the minimum fill at the shoulder on the inside of superelevated curves is 18 inches.<br />
<br />
*Minimum fill heights for vitrified clay pipe (extra strength) are 4 ft. for the 8 to 21 in. diameters and 3 ft. for the 24 to 36 in. diameters.<br />
<br />
Overfill heights which are less than those indicated as allowable for any one pipe type are not considered as justification for the elimination of specifying pipe types by "Group" provided other criteria are satisfactory.<br />
<br />
===750.7.11.2 Design Fill Heights===<br />
For standard concrete box culverts if design fill is between tabulated design fills, use the next greater tabulated design fill, except for design fills between 2 ft. and 4 feet. For design fills between 2 ft. and 4 ft. use the greater member thickness, area of reinforcement and bar dimensions from the 2 ft. and 4 ft. tabulated design fills. For pipe culverts where the fill height is between values tabulated for design, the design fill height is taken to the next increment requiring the higher design. Pipe culverts are designed throughout their length for the maximum design condition except in the case of structural plate pipe.<br />
<br />
A single fill height, representing the maximum height of fill over the culvert, can be used for most box culverts. Additional fill heights may be used for longer culverts, as described in [http://epg.modot.org/index.php?title=751.8_LRFD_Concrete_Box_Culverts#751.8.2.2_Design_Fill EPG 751.8.2.2 Design Fill]. Generally, no more than two or three fill heights should be required. When multiple fill heights are used, consideration should be given to the potential for future widening of the roadbed.<br />
<br />
Design fill heights for all pipe culverts specified by "Group" are shown on the "B" sheets. The allowable overfill heights for corrugated metal pipe-arches and structural plate pipes are tabulated in [[Media:750.7 Overfill Corrugated Metal Pipe-Arches.pdf|Allowable Overfills for Corrugated Metal Pipe-Arches]] and [[Media:750.7 Overfill Structural Plate Pipe.pdf|Allowable Overfills for Structural Plate Pipe]]. These overfill heights indicate both a minimum and a maximum, neither of which should be exceeded. If overfill heights exceed the range shown, a different gage may be necessary and a special design is requested from the Central Office. A special design is also requested for pipe-arches of a size not listed in [[Media:750.7 Overfill Corrugated Metal Pipe-Arches.pdf|Allowable Overfills for Corrugated Metal Pipe-Arches]]. If a different gage is necessary, the plans specify the gage required. Where overfill heights are greater than shown in the figure, consideration should be given to round pipe. The gage for structural plate pipe is specified on the plans and may be changed throughout the length of the structure, where economically feasible, dependent on the fill heights in accordance with [[Media:750.7 Overfill Structural Plate Pipe.pdf|Allowable Overfills for Structural Plate Pipe]].<br />
<br />
===750.7.11.3 Maximum Fill Heights===<br />
====750.7.11.3.1 Box Culverts====<br />
For design fill heights of less than 1 ft. or exceeding 50 ft., a special design request is made to [http://wwwi/intranet/br/default.htm Bridge Division]. A plat showing the culvert location and a cross section at the culvert location should be provided with the request. A special sheet with structural details will be returned to the district. Input on pay item quantities will also be provided.<br />
<br />
====750.7.11.3.2 Pipes====<br />
Design overfill heights which are in excess of those indicated as allowable for any one pipe type are not considered as justification for the elimination of specifying pipe types by "Group" provided other criteria are satisfactory.<br />
<br />
For fill heights exceeding the values tabulated on [http://www.modot.mo.gov/business/standards_and_specs/documents/72630.pdf Std. Plan 726.30] for circular reinforced concrete pipe diameters 36 in. or less, the contractor has the option to supply a special design reinforced concrete pipe in accordance with [http://www.modot.mo.gov/business/standards_and_specs/Sec1026.pdf Sec 1026].<br />
<br />
==750.7.12 Culvert Grades==<br />
Crossroad drainage structures are usually placed parallel to the natural stream slope or the ditch slope in which the culvert is being placed. The invert of most culverts with a width or diameter larger than 48 in. are required to be embedded a minimum of 1 ft. below the natural ditch grade due to [[#750.7.3 Environmental Requirements|environmental requirements]]. Culverts that are not embedded should have a minimum slope of 0.3% to reduce the chances of an adverse slope being created if there is any settlement at the inlet. 0% slopes may be used in special cases or where flow may occur in either direction. Culverts with slopes greater than 10% or with drops more than 25’ may require special connections between culvert sections. See FHWA's ''Hydraulic Design of Highway Culverts – Hydraulic Design Series No. 5 (HDS-5)'' for additional details. Erosion may be a problem at the outlet end of culverts on steep slopes which sometimes can be reduced by breaking the slope within the culvert. Slope breaks can also be used to reduce structure excavation. Drop structures can be used at the inlet end of culverts to reduce the slope through the culvert. Drop structures are used with discretion because of the ponding upstream, and because of the unstable condition that may be created by the ponding. <br />
<br />
Guidance about controlling slopes for [[750.4 Storm Sewers|storm sewers]] and [[750.5 Sanitary Sewers|sanitary sewers]] is available. <br />
<br />
The slope for pipes for median drop inlets is broken in accordance with the requirements and details illustrated on [[Media:750.7 Pipe Grades For Median Drop Inlets.pdf|Pipe Grades For Median Drop Inlets]].<br />
<br />
==750.7.13 Culvert Lengths==<br />
Culvert lengths are determined graphically by scaling from the culvert sections. The lengths are obtained by intersection of the structure with slope lines as shown on the culvert standard plans, and as described in the following sections. Precise lengths are not computed. In questionable cases a longer length is used. Skewed slopes used for culvert sections are shown on [[Media:750.7.13 Slopes for Skewed Culvert Sections.pdf|Slopes for Skewed Culvert Sections]]. Intermediate values are interpolated.<br />
<br />
===750.7.13.1 Box Culverts===<br />
For additional information on culvert length, see [[751.1 Preliminary Design#751.1.2.6.3.2 Length|EPG 751.1.2.6.3.2 Length]]. For maximum length of box culverts and box culvert barrel sections, refer to [[751.8 LRFD Concrete Box Culverts#751.8.3.1 Joints|EPG 751.8.3.1 Joints, Transverse Joints]] and [[751.8 LRFD Concrete Box Culverts#751.8.1.3 Barrel Section Dimensions|EPG 751.8.1.3 Barrel Section Dimensions]]. <br />
<br />
===750.7.13.2 Pipes===<br />
The length of pipe culverts with headwalls is 2 ft. longer than the distance between headwalls. Pipe headwalls are designed on a flat grade, regardless of the grade of the pipe. The length of pipe culverts not beveled and without headwalls is the distance between the slope lines at the flowline. Corrugated metallic-coated steel pipe lengths are scaled to the next higher even foot. Other pipe lengths are scaled to the next higher 1.0 ft. The length of corrugated metallic-coated steel pipes with beveled ends is 2 ft. longer than the distance between the intersection of the slope lines and the centerline of the pipe scaled to the next higher even foot. Pipe bends and special connections are not listed as a pay item on the plans. The plans should include notes to the effect that such items are required and that their costs are included in other items. The plans include, usually on the culvert sections, sufficient dimensions and detail to fabricate pipe with bends or special connections.<br />
<br />
==750.7.14 Excavation for Structure==<br />
See [[:Category:206 Excavation for Structures|EPG 206 Excavation for Structures.]]<br />
<br />
==750.7.15 Connections==<br />
The plans provide for connecting new structures to existing structures, and connecting different types of new structures. The plans do not include an item for the connection of pipes to existing manholes, box culverts, drop inlets or sewer pipes. The plans do include the pipe collar item for connecting different types of pipe or different sizes of pipes. Details for pipe collars are shown on [http://modot.mo.gov/business/standards_and_specs/documents/60440.pdf Standard Plan 604.40].<br />
<br />
==750.7.16 Culvert Cleanout==<br />
Information needed to properly estimate culvert cleanout items are:<br />
*Location of culvert by station<br />
*Type of culvert, i.e. corrugated metal or concrete<br />
*Length of culvert<br />
*Size of culvert<br />
<br />
This information should be listed for each culvert to be cleaned out on the 2B sheets under the heading "Culvert Cleanout, Estimated." This information should be obtained from existing plans; no field measurement is required.<br />
<br />
==750.7.17 Slotted Drains==<br />
Slotted drains may be used to assist in drainage across entrances or very short sections of the roadway edge. Consistent hydraulic characteristics are not available, so slotted drains should not be expected to completely drain a pavement area. Chapter 4 of the FHWA Hydraulic Engineering Circular 22, "HEC-22 Urban Drainage Design" provides guidance for the design of slotted drains. The plans provide for the contractor to select among different styles of slotted drains (See [http://modot.mo.gov/business/standards_and_specs/documents/60470.pdf Standard Plan 604.70]). The diameter of pipe and length of slotted drain are specified in the plans.<br />
<br />
<br />
<br />
[[Category:750 Hydraulic Analysis]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=34307606.1 Guardrail2014-08-29T19:54:53Z<p>Jonesjb: /* 606.1.3.1 3R/4R Projects */ Clarified guardrail considerations for 1R, 2R, 3R, and 4R work.</p>
<hr />
<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
<br />
<br />
==606.1.1 Types of Guardrail==<br />
<br />
'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
<br />
'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
<br />
'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
<br />
'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
<br />
==606.1.2 Guardrail Terms==<br />
<br />
'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
<br />
'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
<br />
'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
<br />
'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
<br />
'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
<br />
==606.1.3 Applications==<br />
<br />
===606.1.3.1 3R/4R Projects===<br />
<br />
The necessity of guardrail modifications must be evaluated when 3R or 4R work is performed on any state-maintained roadway. Guardrail modifications are not generally evaluated for 1R or 2R work except as outlined in [[:Category:128 Conceptual Studies#128.2 Preventive Maintenance Projects (1R and 2R)|EPG 128.2 Preventive Maintenance Projects (1R and 2R)]].<br />
<br />
* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
<br />
* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
<br />
* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
<br />
* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
<br />
* All existing guardrail not warranted by present standards is to be removed.<br />
<br />
* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
<br />
* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
<br />
:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
<br />
:2. Warranted by an analysis of accident history or,<br />
<br />
:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
<br />
<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
<br />
* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
<br />
* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected or unacceptably connected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
<br />
Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
<br />
On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
<br />
:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
<br />
:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
<br />
:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
<br />
:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
<br />
:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
<br />
This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
<br />
===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
<br />
Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
<br />
An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
<br />
Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
<br />
The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
<br />
'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
<br />
'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
<br />
[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
<br />
'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
<br />
'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
<br />
'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
<br />
If any of the following conditions exists a Type E terminal should be used:<br />
<br />
:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
<br />
:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
<br />
'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
<br />
===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system may be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be minimized through grading, the bullnose guardrail system is an appropriate treatment for new construction. This system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
<br />
===606.1.3.4 Anchored in Backslope Guardrail===<br />
<br />
In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
<br />
===606.1.3.5 End Treatment===<br />
<br />
The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
<br />
===606.1.3.6 High Fills===<br />
<br />
Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
<br />
===606.1.3.7 Fixed Objects===<br />
<br />
Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.39 of the ''Roadside Design Guide''.<br />
<br />
===606.1.3.8 Aesthetic Guardrail===<br />
<br />
Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
<br />
There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
<br />
Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
<br />
No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
<br />
===606.1.3.9 Bridge Ends===<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="240px" align="right" <br />
|-<br />
|<center>'''Additional Information'''</center><br />
|-<br />
|align="center"|[[751.1 Preliminary Design#Common Bridge Rails (for Rehabilitations)|Common Bridge Rails (for Rehabilitations)]] Table <br />
|}<br />
<br />
Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
<br />
On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
<br />
The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
<br />
Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an crash history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
<br />
Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded or the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
<br />
Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
<br />
===606.1.3.10 Bridge Piers and Sign Trusses===<br />
<br />
Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
<br />
===606.1.3.11 Signs===<br />
<br />
Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
<br />
===606.1.3.12 Outer Roadways===<br />
<br />
Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
<br />
===606.1.3.13 Headwalls===<br />
<br />
Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
<br />
When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
<br />
===606.1.3.14 Medians===<br />
<br />
Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
<br />
Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
<br />
[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
<br />
===606.1.3.15 Restricted Lateral Clearance===<br />
<br />
When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
<br />
===606.1.3.16 Barricade of Existing Streets and Roads===<br />
<br />
Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
<br />
===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=141.1_Cost_Share_Program&diff=34244141.1 Cost Share Program2014-08-19T15:43:21Z<p>Jonesjb: </p>
<hr />
<div>{|style="border:4px solid #ffcc33; background:#ffff66" align="right" margin-left:8px width="490"<br />
|-<br />
|align="left"|As of January 8, 2014, the Missouri Highways and Transportation Commission unanimously suspended the Cost Share/Economic Development Program for all projects not approved by the Cost-Share Committee at, or prior to, its November 15, 2013, meeting. <br />
|}<br />
<br />
The purpose of the Cost Share/Economic Development Program is to build partnerships with local entities to pool efforts and resources to deliver state highway and bridge projects. MoDOT allocates Cost Share/Economic Development funds based on the [http://www.modot.mo.gov/about/commission/index.htm Missouri Highways and Transportation Commission’s] approved funding distribution formula. At least $5 million is set aside for projects that demonstrate economic development through job creation. Economic development set-aside balances in excess of $25 million are available for any Cost Share/Economic Development project. Projects are selected by the Cost Share/Economic Development Committee, which consists of the Chief Engineer, Chief Financial Officer and the Assistant Chief Engineer. They are then recommended for approval via a STIP amendment. <br />
[[image:141.1.jpg|right|275px]]<br />
<br />
===141.1.1 Eligible Projects===<br />
The Cost Share/Economic Development Program provides financial assistance to public and private applicants for state highway and bridge projects satisfying a transportation need.<br />
<br />
===141.1.2 Types of Cost Share/Economic Development Projects===<br />
<br />
'''Cost Share'''<br />
<br />
MoDOT participates up to 50 percent of the total project costs on the state highway system. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated cost of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. In addition to providing these activities, the district will typically also provide a portion of MoDOT’s 50 percent of the total project costs in the form of funds distributed to the district.<br />
<br />
'''Economic Development'''<br />
<br />
MoDOT participates up to 100 percent of the total project costs on the state highway system, if the project creates jobs that have been verified by the Department of Economic Development. Retail development projects are not eligible. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated amount of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. The project agreement will identify requirements for returning funds if jobs are not created as planned. If a REMI (Regional Economic Modeling, Inc.) analysis is being considered, contact [http://wwwi/intranet/fs/default.htm Financial Services].<br />
<br />
===141.1.3 Application Process===<br />
The applicant works with the appropriate MoDOT district contact to determine the project scope and costs. The district assists the applicant in preparing the Request for Environmental Services (RES) and the Cost Share/Economic Development application. The [http://www.modot.mo.gov/partnershipdevelopment/application.htm application is available online].<br />
<br />
A letter of support from the district engineer must be submitted with the application. The letter of support shall explain in detail the significance of the project and the impact it could have on the department. A letter of support from the [http://www.modot.mo.gov/plansandprojects/long-range_plan/documents/rpcmpo08-06.pdf metropolitan planning organization (MPO) or regional planning commission (RPC)] is also required.<br />
<br />
The items listed below must be submitted to Financial Servies by the established deadline. Applications received after the deadline will be considered at the next Cost Share/Economic Development Committee meeting. Application deadlines are posted on the [http://www.modot.mo.gov/partnershipdevelopment/dates.htm Partnership Development website].<br />
<br />
:* Signed and completed application<br />
:* District Engineer’s support letter<br />
:* MPO’s or RPC’s support letter<br />
:* Traffic models or traffic reports<br />
:* Project map<br />
<br />
===141.1.4 Review Process===<br />
Each application is reviewed for verification of the following criteria:<br />
<br />
:*The total project costs are in excess of $200,000.<br />
:* The total project costs include preliminary engineering, right of way, utilities, construction and construction inspection.<br />
:* The applicant agrees to provide their share of the total project costs on the state highway system and full funding for any portion of the project not on the state highway system.<br />
:* Generally, the Cost Share/Economic Development funding is limited to $20 million in total and $5 million per year. However, projects exceeding this limit have been approved based on factors such as project need, the opportunity for economic development and the willingness of the local partners to be flexible and bring resources to the table. Applicants are encouraged to work with the district and Financial Services to explore options.<br />
:* Additional funds, such as federal earmarks, clearly obtained or held by the applicant are credited to their contribution. All other federal earmarks are applied to the total project costs.<br />
:* If debt financing is used to accelerate the project and complete it earlier than funding is available from MoDOT, the applicant must pay and not include the debt-financing costs in the total project costs. The debt-financing costs include items such as bond counsel, underwriter, financial advisor fees, application fees and interest.<br />
<br />
After initial verification of the application, Financial Services forwards the application to the Cost Share/Economic Development Pre-approval Team.<br />
<br />
The Pre-approval Team consists of staff from Financial Services, Right of Way, Transportation Planning, Design, Traffic and Chief Counsel’s Office. The team is responsible for submitting comments and a recommendation to Financial Services on or before the specified deadline. The Pre-approval Team meets with district staff to discuss the application, resolve any outstanding issues and determine the team’s recommendation to the Cost Share/Economic Development Committee. The Pre-Approval Team ranks each application based on the following criteria:<br />
:* Economic Development<br />
:* Transportation Need<br />
:* Public Benefit<br />
<br />
Financial Services prepares the Cost Share/Economic Development notebooks, which include the meeting agenda, project review sheets, project maps and team recommendations. Notebooks are distributed to the committee members one week prior to the meeting.<br />
<br />
===141.1.5 Approval Process===<br />
The district presents the team’s recommendation for each application to the committee.<br />
<br />
The committee recommends, denies or requests additional information for each application. Recommended projects are included in a subsequent STIP amendment for Commission approval.<br />
<br />
Financial Services provides a letter for the district engineer to send the applicant informing them of the Cost Share/Economic Development Committee’s decision and discussion points. If additional information is needed, Financial Services will compile the requested information and provide it to the committee.<br />
<br />
:'''Project Agreement and Programming Process'''<br />
<br />
:The district works with the approved applicant to draft the Cost Share/Economic Development agreement, using the form RM08 found on the [http://wwwi/intranet/cc/contracts.asp?f=RM&nav=modot Chief Counsel’s Office intranet page]. Agreements include the maximum amount of approved Cost Share/Economic Development funding and the year the funding is available. The district sends the agreement to the “Agreements” list in Lotus Notes for review. The district and applicant address all comments and make appropriate changes to the agreement. The agreement is sent to the Chief Counsel’s Office for a final review before the applicant executes the agreement.<br />
<br />
:The applicant must execute the agreement within six months after the recommendation of the committee to prevent the funds from expiring and being allocated to another project, unless an extension is approved by the committee.<br />
<br />
:If the project is within an MPO, the MPO amends the Transportation Improvement Program (TIP) at this time.<br />
<br />
:Once the applicant executes the agreement (six copies), the district submits the agreement to Financial Services. The district coordinates with Transportation Planning to amend the project to the STIP. Once the month is set for the project to be amended to the STIP, Financial Services sends the agreement to the Chief Counsel’s Office to sign as to form. The Chief Counsel’s Office then forwards the agreement to the Commission Secretary’s Office for approval and execution at the same time the project is amended to the STIP. The funds are contingent upon an executed agreement between the applicant and the Missouri Highways and Transportation Commission (MHTC). Financial Services forwards the fully executed agreement to the district (three copies, two to be forwarded to the applicant), Controller’s Division (one copy), Transportation Planning (one copy) and retains one copy.<br />
<br />
:'''Project Delivery Process'''<br />
<br />
:The district ensures the design, right of way and construction activities comply with the Engineering Policy Guide (EPG).<br />
<br />
Per Financial Services, article renamed and slightly modified. works with Transportation Planning and Controller’s Division to determine funds utilized on projects (at bid award and/or project completion) and returns any excess funds to the Cost Share/Economic Development program.<br />
<br />
[[Category:141 Partnership Development]]</div>Jonesjbhttps://epg.modot.org/index.php?title=141.1_Cost_Share_Program&diff=34243141.1 Cost Share Program2014-08-19T15:42:42Z<p>Jonesjb: Clarified the intent of the sidebar concerning the Commission's suspension of the Cost Share Program.</p>
<hr />
<div>{|style="border:4px solid #ffcc33; background:#ffff66" align="right" margin-left:8px width="490"<br />
|-<br />
|align="center"|As of January 8, 2014, the Missouri Highways and Transportation Commission unanimously suspended the Cost Share/Economic Development Program for all projects not approved by the Cost-Share Committee at, or prior to, its November 15, 2013, meeting. <br />
|}<br />
<br />
The purpose of the Cost Share/Economic Development Program is to build partnerships with local entities to pool efforts and resources to deliver state highway and bridge projects. MoDOT allocates Cost Share/Economic Development funds based on the [http://www.modot.mo.gov/about/commission/index.htm Missouri Highways and Transportation Commission’s] approved funding distribution formula. At least $5 million is set aside for projects that demonstrate economic development through job creation. Economic development set-aside balances in excess of $25 million are available for any Cost Share/Economic Development project. Projects are selected by the Cost Share/Economic Development Committee, which consists of the Chief Engineer, Chief Financial Officer and the Assistant Chief Engineer. They are then recommended for approval via a STIP amendment. <br />
[[image:141.1.jpg|right|275px]]<br />
<br />
===141.1.1 Eligible Projects===<br />
The Cost Share/Economic Development Program provides financial assistance to public and private applicants for state highway and bridge projects satisfying a transportation need.<br />
<br />
===141.1.2 Types of Cost Share/Economic Development Projects===<br />
<br />
'''Cost Share'''<br />
<br />
MoDOT participates up to 50 percent of the total project costs on the state highway system. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated cost of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. In addition to providing these activities, the district will typically also provide a portion of MoDOT’s 50 percent of the total project costs in the form of funds distributed to the district.<br />
<br />
'''Economic Development'''<br />
<br />
MoDOT participates up to 100 percent of the total project costs on the state highway system, if the project creates jobs that have been verified by the Department of Economic Development. Retail development projects are not eligible. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated amount of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. The project agreement will identify requirements for returning funds if jobs are not created as planned. If a REMI (Regional Economic Modeling, Inc.) analysis is being considered, contact [http://wwwi/intranet/fs/default.htm Financial Services].<br />
<br />
===141.1.3 Application Process===<br />
The applicant works with the appropriate MoDOT district contact to determine the project scope and costs. The district assists the applicant in preparing the Request for Environmental Services (RES) and the Cost Share/Economic Development application. The [http://www.modot.mo.gov/partnershipdevelopment/application.htm application is available online].<br />
<br />
A letter of support from the district engineer must be submitted with the application. The letter of support shall explain in detail the significance of the project and the impact it could have on the department. A letter of support from the [http://www.modot.mo.gov/plansandprojects/long-range_plan/documents/rpcmpo08-06.pdf metropolitan planning organization (MPO) or regional planning commission (RPC)] is also required.<br />
<br />
The items listed below must be submitted to Financial Servies by the established deadline. Applications received after the deadline will be considered at the next Cost Share/Economic Development Committee meeting. Application deadlines are posted on the [http://www.modot.mo.gov/partnershipdevelopment/dates.htm Partnership Development website].<br />
<br />
:* Signed and completed application<br />
:* District Engineer’s support letter<br />
:* MPO’s or RPC’s support letter<br />
:* Traffic models or traffic reports<br />
:* Project map<br />
<br />
===141.1.4 Review Process===<br />
Each application is reviewed for verification of the following criteria:<br />
<br />
:*The total project costs are in excess of $200,000.<br />
:* The total project costs include preliminary engineering, right of way, utilities, construction and construction inspection.<br />
:* The applicant agrees to provide their share of the total project costs on the state highway system and full funding for any portion of the project not on the state highway system.<br />
:* Generally, the Cost Share/Economic Development funding is limited to $20 million in total and $5 million per year. However, projects exceeding this limit have been approved based on factors such as project need, the opportunity for economic development and the willingness of the local partners to be flexible and bring resources to the table. Applicants are encouraged to work with the district and Financial Services to explore options.<br />
:* Additional funds, such as federal earmarks, clearly obtained or held by the applicant are credited to their contribution. All other federal earmarks are applied to the total project costs.<br />
:* If debt financing is used to accelerate the project and complete it earlier than funding is available from MoDOT, the applicant must pay and not include the debt-financing costs in the total project costs. The debt-financing costs include items such as bond counsel, underwriter, financial advisor fees, application fees and interest.<br />
<br />
After initial verification of the application, Financial Services forwards the application to the Cost Share/Economic Development Pre-approval Team.<br />
<br />
The Pre-approval Team consists of staff from Financial Services, Right of Way, Transportation Planning, Design, Traffic and Chief Counsel’s Office. The team is responsible for submitting comments and a recommendation to Financial Services on or before the specified deadline. The Pre-approval Team meets with district staff to discuss the application, resolve any outstanding issues and determine the team’s recommendation to the Cost Share/Economic Development Committee. The Pre-Approval Team ranks each application based on the following criteria:<br />
:* Economic Development<br />
:* Transportation Need<br />
:* Public Benefit<br />
<br />
Financial Services prepares the Cost Share/Economic Development notebooks, which include the meeting agenda, project review sheets, project maps and team recommendations. Notebooks are distributed to the committee members one week prior to the meeting.<br />
<br />
===141.1.5 Approval Process===<br />
The district presents the team’s recommendation for each application to the committee.<br />
<br />
The committee recommends, denies or requests additional information for each application. Recommended projects are included in a subsequent STIP amendment for Commission approval.<br />
<br />
Financial Services provides a letter for the district engineer to send the applicant informing them of the Cost Share/Economic Development Committee’s decision and discussion points. If additional information is needed, Financial Services will compile the requested information and provide it to the committee.<br />
<br />
:'''Project Agreement and Programming Process'''<br />
<br />
:The district works with the approved applicant to draft the Cost Share/Economic Development agreement, using the form RM08 found on the [http://wwwi/intranet/cc/contracts.asp?f=RM&nav=modot Chief Counsel’s Office intranet page]. Agreements include the maximum amount of approved Cost Share/Economic Development funding and the year the funding is available. The district sends the agreement to the “Agreements” list in Lotus Notes for review. The district and applicant address all comments and make appropriate changes to the agreement. The agreement is sent to the Chief Counsel’s Office for a final review before the applicant executes the agreement.<br />
<br />
:The applicant must execute the agreement within six months after the recommendation of the committee to prevent the funds from expiring and being allocated to another project, unless an extension is approved by the committee.<br />
<br />
:If the project is within an MPO, the MPO amends the Transportation Improvement Program (TIP) at this time.<br />
<br />
:Once the applicant executes the agreement (six copies), the district submits the agreement to Financial Services. The district coordinates with Transportation Planning to amend the project to the STIP. Once the month is set for the project to be amended to the STIP, Financial Services sends the agreement to the Chief Counsel’s Office to sign as to form. The Chief Counsel’s Office then forwards the agreement to the Commission Secretary’s Office for approval and execution at the same time the project is amended to the STIP. The funds are contingent upon an executed agreement between the applicant and the Missouri Highways and Transportation Commission (MHTC). Financial Services forwards the fully executed agreement to the district (three copies, two to be forwarded to the applicant), Controller’s Division (one copy), Transportation Planning (one copy) and retains one copy.<br />
<br />
:'''Project Delivery Process'''<br />
<br />
:The district ensures the design, right of way and construction activities comply with the Engineering Policy Guide (EPG).<br />
<br />
Per Financial Services, article renamed and slightly modified. works with Transportation Planning and Controller’s Division to determine funds utilized on projects (at bid award and/or project completion) and returns any excess funds to the Cost Share/Economic Development program.<br />
<br />
[[Category:141 Partnership Development]]</div>Jonesjbhttps://epg.modot.org/index.php?title=141.1_Cost_Share_Program&diff=34237141.1 Cost Share Program2014-08-18T16:06:49Z<p>Jonesjb: Added color to notice to increase target value</p>
<hr />
<div>{|style="border:4px solid #ffcc33; background:#ffff66" align="right" margin-left:8px width="490"<br />
|-<br />
|align="center"|As of January 8, 2014, the Missouri Highway and Transportation Commission unanimously suspended the addition of new highway improvement projects to the STIP EXCEPT projects approved by the Cost Share Committee at its November 15, 2013, meeting after applicable projects agreements with the local sponsors have been fully executed. <br />
|}<br />
<br />
The purpose of the Cost Share/Economic Development Program is to build partnerships with local entities to pool efforts and resources to deliver state highway and bridge projects. MoDOT allocates Cost Share/Economic Development funds based on the [http://www.modot.mo.gov/about/commission/index.htm Missouri Highways and Transportation Commission’s] approved funding distribution formula. At least $5 million is set aside for projects that demonstrate economic development through job creation. Economic development set-aside balances in excess of $25 million are available for any Cost Share/Economic Development project. Projects are selected by the Cost Share/Economic Development Committee, which consists of the Chief Engineer, Chief Financial Officer and the Assistant Chief Engineer. They are then recommended for approval via a STIP amendment. <br />
[[image:141.1.jpg|right|275px]]<br />
<br />
===141.1.1 Eligible Projects===<br />
The Cost Share/Economic Development Program provides financial assistance to public and private applicants for state highway and bridge projects satisfying a transportation need.<br />
<br />
===141.1.2 Types of Cost Share/Economic Development Projects===<br />
<br />
'''Cost Share'''<br />
<br />
MoDOT participates up to 50 percent of the total project costs on the state highway system. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated cost of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. In addition to providing these activities, the district will typically also provide a portion of MoDOT’s 50 percent of the total project costs in the form of funds distributed to the district.<br />
<br />
'''Economic Development'''<br />
<br />
MoDOT participates up to 100 percent of the total project costs on the state highway system, if the project creates jobs that have been verified by the Department of Economic Development. Retail development projects are not eligible. The amount of Cost Share/Economic Development funds allocated to a project is reduced by the estimated amount of activities performed by MoDOT such as preliminary engineering, right of way incidentals and construction inspection. The project agreement will identify requirements for returning funds if jobs are not created as planned. If a REMI (Regional Economic Modeling, Inc.) analysis is being considered, contact [http://wwwi/intranet/fs/default.htm Financial Services].<br />
<br />
===141.1.3 Application Process===<br />
The applicant works with the appropriate MoDOT district contact to determine the project scope and costs. The district assists the applicant in preparing the Request for Environmental Services (RES) and the Cost Share/Economic Development application. The [http://www.modot.mo.gov/partnershipdevelopment/application.htm application is available online].<br />
<br />
A letter of support from the district engineer must be submitted with the application. The letter of support shall explain in detail the significance of the project and the impact it could have on the department. A letter of support from the [http://www.modot.mo.gov/plansandprojects/long-range_plan/documents/rpcmpo08-06.pdf metropolitan planning organization (MPO) or regional planning commission (RPC)] is also required.<br />
<br />
The items listed below must be submitted to Financial Servies by the established deadline. Applications received after the deadline will be considered at the next Cost Share/Economic Development Committee meeting. Application deadlines are posted on the [http://www.modot.mo.gov/partnershipdevelopment/dates.htm Partnership Development website].<br />
<br />
:* Signed and completed application<br />
:* District Engineer’s support letter<br />
:* MPO’s or RPC’s support letter<br />
:* Traffic models or traffic reports<br />
:* Project map<br />
<br />
===141.1.4 Review Process===<br />
Each application is reviewed for verification of the following criteria:<br />
<br />
:*The total project costs are in excess of $200,000.<br />
:* The total project costs include preliminary engineering, right of way, utilities, construction and construction inspection.<br />
:* The applicant agrees to provide their share of the total project costs on the state highway system and full funding for any portion of the project not on the state highway system.<br />
:* Generally, the Cost Share/Economic Development funding is limited to $20 million in total and $5 million per year. However, projects exceeding this limit have been approved based on factors such as project need, the opportunity for economic development and the willingness of the local partners to be flexible and bring resources to the table. Applicants are encouraged to work with the district and Financial Services to explore options.<br />
:* Additional funds, such as federal earmarks, clearly obtained or held by the applicant are credited to their contribution. All other federal earmarks are applied to the total project costs.<br />
:* If debt financing is used to accelerate the project and complete it earlier than funding is available from MoDOT, the applicant must pay and not include the debt-financing costs in the total project costs. The debt-financing costs include items such as bond counsel, underwriter, financial advisor fees, application fees and interest.<br />
<br />
After initial verification of the application, Financial Services forwards the application to the Cost Share/Economic Development Pre-approval Team.<br />
<br />
The Pre-approval Team consists of staff from Financial Services, Right of Way, Transportation Planning, Design, Traffic and Chief Counsel’s Office. The team is responsible for submitting comments and a recommendation to Financial Services on or before the specified deadline. The Pre-approval Team meets with district staff to discuss the application, resolve any outstanding issues and determine the team’s recommendation to the Cost Share/Economic Development Committee. The Pre-Approval Team ranks each application based on the following criteria:<br />
:* Economic Development<br />
:* Transportation Need<br />
:* Public Benefit<br />
<br />
Financial Services prepares the Cost Share/Economic Development notebooks, which include the meeting agenda, project review sheets, project maps and team recommendations. Notebooks are distributed to the committee members one week prior to the meeting.<br />
<br />
===141.1.5 Approval Process===<br />
The district presents the team’s recommendation for each application to the committee.<br />
<br />
The committee recommends, denies or requests additional information for each application. Recommended projects are included in a subsequent STIP amendment for Commission approval.<br />
<br />
Financial Services provides a letter for the district engineer to send the applicant informing them of the Cost Share/Economic Development Committee’s decision and discussion points. If additional information is needed, Financial Services will compile the requested information and provide it to the committee.<br />
<br />
:'''Project Agreement and Programming Process'''<br />
<br />
:The district works with the approved applicant to draft the Cost Share/Economic Development agreement, using the form RM08 found on the [http://wwwi/intranet/cc/contracts.asp?f=RM&nav=modot Chief Counsel’s Office intranet page]. Agreements include the maximum amount of approved Cost Share/Economic Development funding and the year the funding is available. The district sends the agreement to the “Agreements” list in Lotus Notes for review. The district and applicant address all comments and make appropriate changes to the agreement. The agreement is sent to the Chief Counsel’s Office for a final review before the applicant executes the agreement.<br />
<br />
:The applicant must execute the agreement within six months after the recommendation of the committee to prevent the funds from expiring and being allocated to another project, unless an extension is approved by the committee.<br />
<br />
:If the project is within an MPO, the MPO amends the Transportation Improvement Program (TIP) at this time.<br />
<br />
:Once the applicant executes the agreement (six copies), the district submits the agreement to Financial Services. The district coordinates with Transportation Planning to amend the project to the STIP. Once the month is set for the project to be amended to the STIP, Financial Services sends the agreement to the Chief Counsel’s Office to sign as to form. The Chief Counsel’s Office then forwards the agreement to the Commission Secretary’s Office for approval and execution at the same time the project is amended to the STIP. The funds are contingent upon an executed agreement between the applicant and the Missouri Highways and Transportation Commission (MHTC). Financial Services forwards the fully executed agreement to the district (three copies, two to be forwarded to the applicant), Controller’s Division (one copy), Transportation Planning (one copy) and retains one copy.<br />
<br />
:'''Project Delivery Process'''<br />
<br />
:The district ensures the design, right of way and construction activities comply with the Engineering Policy Guide (EPG).<br />
<br />
Per Financial Services, article renamed and slightly modified. works with Transportation Planning and Controller’s Division to determine funds utilized on projects (at bid award and/or project completion) and returns any excess funds to the Cost Share/Economic Development program.<br />
<br />
[[Category:141 Partnership Development]]</div>Jonesjbhttps://epg.modot.org/index.php?title=131.1_Design_Exception_Process&diff=34100131.1 Design Exception Process2014-07-21T18:19:32Z<p>Jonesjb: /* 131.1.5.1 Safety related features */ Clarified intent of HSM analysis.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%;background:#f5f5f5" width="160px" align="right" <br />
|-style="background:#f5f5f5" <br />
|align-"center"|'''Forms'''<br />
|-style="background:#f5f5f5"<br />
|valign="top" align="center"| [[media:131.1 Design Exception.docx|Design Exception Information Form]]<br />
|-<br />
|[http://ghepg01/forms/BR/Vertical%20Clearance%20Design%20Exception%20Coordination%20with%20SDDCTEA%20Form.doc Vertical Clearance Design Exception Coordination with SDDCTEA]<br />
|}<br />
<br />
<br />
==131.1.1 When to Complete a Design Exception==<br />
<br />
A design exception documents design elements of an improvement that vary from engineering policy. In most cases the need for an exception results from an inability to reasonably meet the design criteria.<br />
<br />
An approved exception simply documents the engineering-based determination that variance from MoDOT’s engineering policy is necessary and appropriate. It is the primary tool to detail not only the decision itself, but also what was considered when the decision was made. <br />
<br />
When there is doubt whether a design exception is required, the Engineering Policy Administrator, Assistant State Bridge Engineer or the Design Liaison Engineer (DLE) for the district should be consulted. <br />
<br />
A design exception is encouraged whenever it is feasibly or technically impossible to reasonably meet the preferred design criteria or wherever there is potential for additional value outside of written engineering policy. Design exceptions should not be considered breaches of policy as much as opportunities to add practicality or value to the design. <br />
<br />
An approved exception is not a request for permission; rather, it simply documents deliberate variances from engineering policy. <br />
<br />
==131.1.2 The 13 Controlling Criteria==<br />
<br />
There are 13 design criteria that the FHWA has identified as the most important or critical elements. A MoDOT and FHWA approved written design exception is required if design criteria, as established in MoDOT’s EPG, is not met for any of these 13 elements on a non-exempt (full-oversight) project. <br />
<br />
The 13 controlling criteria are:<br />
<br />
:1) Design Speed<br />
:2) Lane Width<br />
:3) Shoulder Width <br />
:4) Bridge Width<br />
:5) Horizontal Alignment<br />
:6) Superelevation<br />
:7) Vertical Alignment<br />
:8) Grade<br />
:9) Stopping Sight Distance<br />
:10) Cross Slope<br />
:11) Vertical Clearance<br />
:12) Lateral Offset to Obstruction<br />
:13) Structural Capacity<br />
<br />
A MoDOT approved design exception is required for all other non-complying design elements on non-exempt projects and for all non-complying design elements on exempt (not full-oversight) projects. <br />
<br />
==131.1.3 Definition of Exempt and Non-Exempt Projects==<br />
<br />
See [http://epg.modot.org/index.php?title=Category:123_Federal-Aid_Highway_Program#123.1.1_FHWA_Oversight_-_National_Highway_System EPG 123.1.1 FHWA Oversight - National Highway System] for definitions of exempt and non-exempt (full-oversight) projects. <br />
<br />
==131.1.4 The Design Exception Process==<br />
<br />
Requests for design exceptions are submitted when the need first arises; however, they may be submitted at any time and specifically along with the [[:Category:128 Conceptual Studies|conceptual study]], [[:Category:235 Preliminary Plans|preliminary plan]], right of way certification, or plans, specifications, and estimate (PS&E). In general, it is best to identify and consider the design exception as early as practical in the design process.<br />
<br />
When the need for a design exception has been identified, the project manager, Structural Project Manager or consultant representative is responsible for completing the standard [[media:131.1 Design Exception.docx|Design Exception Information Form]]. The form must include a detailed description of the rationale for the change and the appropriate supporting documentation to satisfactorily justify the decision and document any mitigation efforts associated with varying from the engineering policy. Examples of approved Design Exceptions can be found here<provide link>. (Please note that previous approval of an item should not be considered approval of the item on any future project. Approval for future projects must be sought on a case-by-case basis.)<br />
<br />
Project managers (consultant, transportation or bridge) and their design staff should recognize the importance of an open and transparent decision making process while considering the suitability and appropriateness of a given design element that is not consistent with our current policies. Since our engineering policy is established through a collaborative effort, it is critical to engage all appropriate staff when making the decision not to meet our policies. While completing the form, communication with the appropriate staff, including the Design Liaison Engineer, a representative of any affected MoDOT division and FHWA (when applicable), is critical to ensure efficient and effective review and approval. For efficient processing and to avoid delays, this communication should occur prior to the formal submittal. Depending upon the item being excepted and the type of project, the appropriate review staff and signatory parties will vary. <br />
<br />
A copy of every fully approved design exception is provided to the [http://wwwi/design/default.htm Central Office Design Division] for the permanent project file. A copy of the form is also kept in the district file, and a copy of bridge-related exceptions is retained by the [http://wwwi/intranet/br/default.htm Bridge Division].<br />
<br />
It should be noted that the Federal Highway Administration (FHWA) reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight. <br />
<br />
===131.1.4.1 The Development, Concurrence and Approval Process===<br />
<br />
In addition to the applicable process requirements described below, vertical clearance design exceptions on the interstate must also follow the additional requirement described in [[#131.1.7 Deficient Vertical Clearances on Interstates|EPG 131.1.7 Deficient Vertical Clearances on Interstates]].<br />
<br />
====131.1.4.1.1 Roadway Design Exceptions====<br />
Upon the core team's determination that a design exception is warranted, the following process should be used for design exception submittals relating to roadway items only:<br />
<br />
'''Conceptual Approval:'''<br />
<br />
:1) The Transportation Project Manager (TPM) working with the Consultant Project Manager, if applicable, submits the design exception form, submittal letter and supporting information to the Design Liaison Engineer (DLE), the District Design Engineer (DDE), FHWA (if applicable) and any other pertinent district and division staff.<br />
<br />
:2) The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue.<br />
<br />
:3) The TPM works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception. <br />
<br />
:4) The TPM submits the design exception for signature according to flowchart below.<br />
<br />
'''Formal Approval: '''<br />
<br />
Signatures for approval should be obtained in accordance with the following flowchart:<br />
<br />
[[image:131.1.4.1.1.jpg|center|650px|thumb|<center>'''Route as appropriate to obtain approvals in the appropriate order.'''</center>]]<br />
<br />
<br />
====131.1.4.1.2 Bridge Design Exceptions==== <br />
The following process should be used for design exception submittals relating to bridge items:<br />
<br />
'''Conceptual Approval:'''<br />
<br />
:1. The Structural Project Manager (SPM), or the Structural Liaison Engineer (SLE) working with the Consultant Project Manager submits the design exception form, submittal letter and supporting information to the Assistant State Bridge Engineer, the Design Liaison Engineer (DLE), the Transportation Project Manager, FHWA (if applicable) and any other pertinent district and division staff.<br />
<br />
:2. The contacted division and district representatives will respond with any necessary comments or concerns, request additional information if necessary or will request an opportunity to meet and discuss the issue (if significant objection is determined). <br />
<br />
:3. The SPM/SLE works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception. <br />
<br />
:4. The SPM/SLE submits the design exception for signature according to the flowchart below.<br />
<br />
'''Formal Approval:'''<br />
<br />
Signatures for approval should be obtained in accordance with the following flowchart:<br />
<br />
[[image:131.1.4.1.2.jpg|center|600px|thumb|<center>'''Route as appropriate to obtain approvals in the appropriate order.'''</center>]]<br />
<br />
====131.1.4.1.3 Both Roadway and Bridge Item Related Design Exceptions====<br />
Occasionally, both roadway and bridge items will need to be included. In these instances, the TPM and the SLE/SLM should agree to a single point of contact for the review, concurrence and approval of the design exception and will ensure that the appropriate staff members are properly engaged throughout the process.<br />
<br />
===131.1.4.2 Issue Resolution===<br />
<br />
The review and concurrence process is intended to avoid any significant objections, questions or concerns during the approval process, however, occasionally these issues may arise. In this instance, the design exception approval process may be put on hold until the issue can be resolved by the appropriate staff members. The TPM or SLE/SLM will remain the primary contact to address any request for additional information or consideration.<br />
<br />
===131.1.4.3 Design Exception Numbering and Logging===<br />
<br />
As design exceptions serve as the permanent record of the design decision, providing a design exception numbering and logging system will benefit tracking the submittal and return of each exception and to ensure that all design exceptions are acknowledged and accounted for. The preferred design exception numbering system is the job number followed by a sequential number for each design exception. For example, the first roadway design exception for project JXPXXXX would be Design Exception (DE) # JXPXXXX-R1. The second would be JXPXXXX-R2, and so forth. The first bridge design exception for project JXPXXXX would be DE# JXPXXXX-B1. If a design exception includes both roadway and bridge items, it will be numbered and logged according to who initiates the design exception. The logging system in each project file should indicate the design exception number and the date submitted and date received. If a design exception is not approved, the number should be recorded and noted that it was not approved. The next design exception would be numbered with the next available number. Additionally, as a best management practice, the design exception log and the design exceptions themselves may be located in the project file or a project SharePoint site. <br />
<br />
==131.1.5 Required Information==<br />
<br />
Whenever the engineering policy cannot be met, data for only those non-standard items is listed. This data includes a brief description of the project and the improvement goals that are being attempted. This information is required since the context of the project often helps in deciding if approval of the exception is appropriate. Additionally, the data should include the details related to the existing feature (if applicable), the desired design criteria for that feature, the proposed solution, and the location (limits) associated with the solution. The column shown for existing features is not applicable to new construction. The appropriate values for desired design criteria are shown in the second column. The design criteria for new construction on rural and urban highways are stated in individual articles pertaining to each geometric element discussed in the [[:Category:200 GEOMETRICS|EPG 200 Geometrics]] articles. Design criteria for 3R and 4R projects are discussed in [[:Category:128 Conceptual Studies|EPG 128 Conceptual Studies]]. The criteria for proper access management can be found in [[:Category:940 Access Management|EPG Access Management]]. <br />
<br />
All design exceptions must suitably explain the justification for the exception. It is imperative that this justification be sufficiently complete to clearly reflect that the designer exercised reasonable care in the selection of a particular highway design. Design exceptions often arise because it is impractical or impossible to reasonably meet engineering policy. The justification may include appropriate economic analysis, discussion of applicable accident location and type or discussion of avoidance of [[127.10 Section 4(f) Public Lands#127.10.2.1.1 Section 4(f) Properties|Section 4(f)]] or [[127.10 Section 4(f) Public Lands#127.10.2.1.2 Section 6(f) Properties|Section 6(f)]] lands. The justification supports the concept that maximum service and safety benefits were realized for the cost invested. Engineering judgment is used when balancing the economic and engineering reasons for the justification. A design exception is based on sound engineering judgment rather than being solely an attempt to save cost.<br />
<br />
===131.1.5.1 Safety related features===<br />
<br />
If the design exception request involves any features that are safety related, then sufficient accident data and history is attached to the request to support the reasons for justification. A summary report of the accident information is acceptable if the volume of the data is excessive. Examples of safety related features include, but not limited to, the following: lane width, shoulder width, shoulder type, rumble strips, turn lanes, bridge width, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance, guardrail, etc. Any other items that may be perceived as a safety concern will also follow these requirements. <br />
<br />
In addition, if the design exception request involves safety related features that are adequately addressed in the AASHTO ''Highway Safety Manual'', then documentation of the exception should include a safety analysis as described in the manual. Typically, this process will involve two primary determinations. <br />
*Calculate the expected change in crashes from existing conditions to standard design conditions<br />
*Calculate the expected change in crashes from existing conditions to the proposed design<br />
<br />
The proposed design should take into account any design exceptions as well as any additional safety features above and beyond the standard design. <br />
<br />
By making these two determinations, a quantitative safety comparison can be made between existing conditions, the standard design, and the proposed design. This information, along with other project considerations, can be used to help determine the best design alternative. A list of features currently addressed by the manual include: lane width, shoulder width, shoulder type, center line rumble strips, horizontal alignment (length, radius), grade, roadside hazard rating, fixed objects, driveway density, median width, sideslope, lighting, intersection skew angle and turn lanes. Not all features in the manual are addressed for each facility type.<br />
<br />
===131.1.5.2 The Submittal Letter===<br />
<br />
A transmittal letter that describes the nature of the exceptions that are requested will accompany each design exception request. This information is required since the context of the project often helps in deciding if approval of the exception is appropriate. The Bridge Division will provide the transmittal letter for design exceptions they initiate.<br />
<br />
===131.1.6 Revising an Approved Design Exception ===<br />
<br />
Changes in project scope or design criteria can result in changes to design exceptions that have previously been considered. In these cases, a revised design exception must be completed and approved (as described above). The original design exception should accompany the revised information in order to illustrate the changes. The transmittal letter should address the changes and an explanation of the circumstances leading to the revision. <br />
<br />
==131.1.7 Deficient Vertical Clearances on Interstates==<br />
<br />
Maintaining the integrity of interstates for national defense purposes has long been recognized. Interstates are intended to be constructed and maintained to meet AASHTO Policy as stated in ''A Policy on Design Standards - Interstate System'', which is incorporated by reference in [http://www.fhwa.dot.gov/legsregs/directives/fapg/cfr0625.htm 23 CFR 625]. Maintaining standard vertical clearances to the extent possible for defense mobilization is considered particularly important and is a focus at the national level. As a result, the [http://www.fhwa.dot.gov/ FHWA] has agreed that all exceptions to a 16 ft. vertical clearance standard for the rural interstate and certain single routings on the urban interstates be coordinated with the [http://www.tea.army.mil/ Surface Deployment and Distribution Command Transportation Engineering Agency (SDDCTEA)] of the Department of Defense. This coordination applies whether it is a new construction project, a project that does not provide for the correction of an existing substandard condition, or a project that creates a substandard condition at an existing structure. The steps involved are: <br />
<br />
:1. For a vertical clearance over any interstate highway that will be less than 16 ft. meeting the above criteria, the district submits to the [http://wwwi/design/default.htm Design Division] a completed SDDCTEA Interstate Vertical Clearance Coordination Form along with a Design Exception for vertical clearance.<br />
<br />
:2 The Design Liaison Engineer emails the Bridge Inventory Analysts and requests the Structure NBI number for box 2 on the Vertical Clearance Design Exception Coordination with SDDCTEA Form.<br />
<br />
:3. Concurrent with the submission or routing of the Design Exception, the Design Liaison Engineer submits the form to the SDDCTEA and copies FHWA. This may be done electronically using the contact information on the [http://ghepg01/forms/BR/Vertical%20Clearance%20Design%20Exception%20Coordination%20with%20SDDCTEA%20Form.doc Vertical Clearance Design Exception Coordination with SDDCTEA].<br />
<br />
:4. A response from SDDCTEA should occur within 10 working days following receipt of the coordination request. Receipt of the request can be verified with SDDCTEA via telephone or fax. If there is no response after 10 working days following receipt, it can be determined that SDDCTEA does not have any concerns about the proposed exception.<br />
<br />
:5. The Design Liaison Engineer informs FHWA as to the final outcome of the SDDCTEA request. <br />
<br />
[[category:131 Other General Procedures|131.01]]</div>Jonesjbhttps://epg.modot.org/index.php?title=File:409_JSP_FY15.doc&diff=34055File:409 JSP FY15.doc2014-07-11T18:23:41Z<p>Jonesjb: </p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=Category:409_Seal_Coat&diff=34054Category:409 Seal Coat2014-07-11T18:23:28Z<p>Jonesjb: </p>
<hr />
<div>[[image:409 Distributor Sealing Operation.jpg|right|400px|thumb|<center>'''Distributor sealing operation'''</center>]]<br />
Seal Coating or chip sealing is the application of a bituminous binder immediately followed by the application of an aggregate cover. The aggregate is then rolled to embed it into the binder. The desired functions of a seal coat/chip seal are:<br />
:1. Seal the road surface against the entrance of moisture and air.<br />
:2. Provide a new skid resistance wearing surface.<br />
:3. Rejuvenate or enliven a dry or weathered surface against abrasion and disintegration.<br />
:4. Reinforce and help restore design surface.<br />
:5. Provide a demarcation in texture between the road surface and the shoulders for traffic guidance.<br />
:6. Cover ragged patches and other discrepancies.<br />
<div id="Seal coats/chip seals"></div><br />
Seal coats/chip seals cannot be used to correct the pavement profile or correct a rough ride. When selecting a roadway for chip sealing, the existing pavement should exhibit a good cross section and a good base, and have a good ride quality. Working cracks should be sealed, and non-working cracks &ge; 3/8 in. wide should be filled prior to the placement of the chip seal (For more information on working and nonworking cracks see [[413.5 Crack Treatment in Bituminous Pavements|Crack Treatment in Bituminous Pavements]]).<br />
<br />
<br />
{|border="4" align="right" style="margin-left:10px"<br />
|-<br />
|style="background:#BEBEBE" align="center"|'''[[media:409_FY2015_Contract_Seal_Coat_Guidelines.pdf|Contract Seal Coat Guidelines]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center" | '''[[media:409_JSP_FY15.doc|Job Special Provisions]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center"|''' [[media:409_SEAL_COAT_MODOT_STRIPING.pdf|PDFs of Contract Seal Coat Plan Templates]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center" width=400|Contact Bidding and Contract Services, Danica Stovall-Taylor, for additional guidance. <br />
|}<br />
<br />
==409.1 Design==<br />
In contracts using [http://modot.mo.gov/business/standards_and_specs/Sec0409.pdf Standard Specification Section 409], the type of bituminous material and grade of liquid asphalt is selected by the contractor. Differing aggregate qualities are available and specified according to the roadway traffic. Grade C is used only on roads with AADT < 750. Grade B is used on two-lane, two-way roads with AADT < 1700, and divided roads with AADT < 3500. Grade A is used on two-lane, two-way roads with AADT < 3500, and divided roads with AADT < 14,000. Grade C is used for all shoulder applications. To improve the perception of the driving public, Sec 409 requires the finished seal coat to have a dark appearance. See [[751.1 Preliminary Design#751.1.3.6 Asphalt Wearing Surface|EPG 751.1.3.6 Asphalt Wearing Surface]] for guidelines on aggregate grade selection for bridges.<br />
<br />
A seal coat placed on a porous surface such as an aggregate base should receive a [[:Category:408 Prime Coat|prime coat]].<br />
<br />
==409.2 Construction Inspection for Sec 409==<br />
===409.2.1 Description (Sec 409.1)===<br />
Seal coats, also known as chip seals, are used to lengthen the service life of an existing pavement by waterproofing it and improving its surface texture.<br />
<br />
===409.2.2 Material (Sec 409.2)===<br />
See also [[:Category:1003 Aggregate for Seal Coats|1003 Aggregate for Seal Coats]] and [[:Category:1015 Bituminous Material|EPG 1015 Bituminous Material]].<br />
<br />
===409.2.3 Job Mix Formula (Sec 409.3)===<br />
Proper design of a seal coat consists of determining the proper rate of application for the<br />
bituminous material and cover aggregate. The mix design procedure will be in accordance with<br />
[[#409.2 Materials Inspection for Sec 409|Materials Inspection]].<br />
<br />
===409.2.4 Equipment (Sec 409.4)===<br />
See [[460.4 Paving Equipment|Distributor]] in Paving Equipment. A rotary power broom or vacuum sweeper will be used to remove excess loose aggregate. Pneumatic tire rollers will be used to embed the cover aggregate. The contact pressure of the tires shall be at least 80 psi. In order to achieve the required contact pressure, the contractor may need to adjust the inflation pressure of the tires.<br />
<br />
===409.2.5 Construction Requirements (Sec 409.5)===<br />
<br />
'''Weather Limitations''' (Sec 409.5.2)<br />
<br />
See [[460.6 Paving Operations#460.6.3 Weather Conditions|Weather Conditions]] in Paving Operations.<br />
<br />
'''Application of Bituminous Material''' (Sec 409.5.4)<br />
<br />
See [[460.4 Paving Equipment|Distributor]] in Paving Equipment. Excess binder works upward to the surface of the pavement and creates a black, sticky surface condition (i.e., flushing, bleeding, etc.). In wet weather, the surface may become slippery. A black appearance in the surface can also be the result of insufficient cover aggregate or a loss of cover aggregate.<br />
<br />
Applying too little binder to the surface leads to a loss of cover aggregate because insufficient binder is present to hold the aggregate in place. Generally, the use of too little binder occurs less frequently than the use of too much.<br />
<br />
'''Application of Cover Aggregate''' (Sec 409.5.5)<br />
<br />
Cover aggregate is applied with a self-propelled spreader. Aggregate spreading should progress rapidly as a continuous operation. Stopping and starting of the distributor and/or aggregate spreader should be held to a minimum. The operation shall proceed in such a manner that the binder will not be permitted to cool, set up, dry or otherwise impair retention of the cover aggregate. To achieve this, the maximum time interval between applying the binder and spreading the cover aggregate should be limited to 30 seconds.<br />
<br />
Any deficiencies in application of cover aggregate resulting in uncovered areas or nonuniform<br />
application of aggregate should be immediately corrected behind the spreading equipment. Any excess aggregate should be removed immediately to avoid damage to the seal coat and possible build up of materials, which could adversely affect the ride quality. Pull brooms or drags should not be used to distribute cover aggregate until embedded aggregate is set. If dust is a nuisance or impairs visibility, the contractor will be required to pre-coat the aggregate.<br />
<br />
The rolling operation should immediately follow spreading to embed the aggregate while the binder is still soft and tacky. Pneumatic tired rollers must be operated slow enough to prevent<br />
the tires from displacing or picking up aggregate. All rolling must be completed the same day that the binder and aggregate have been applied. All loose aggregate must be removed before the<br />
roadway is opened to traffic.<br />
<br />
The major causes of loss of cover aggregate are insufficient binder, dirty or dust covered aggregate, or opening the roadway to traffic before the seal coat has cured. If there is a long delay between the application of the binder and the cover aggregate, even during warm weather, the binder may cool and harden and good adhesion is seriously impaired.<br />
<br />
:Sec 409.5.5.1 If required by the contract, a seal coat may be applied to a bridge deck before a new hot-mix asphalt (HMA) surface is placed using the following guidelines. If an emulsion is used in the seal coat, the HMA surface may be placed in the same day. However, the haul trucks must not be allowed to make turning movements on the fresh seal coat application so that displacement of the cover aggregate does not occur. If a cutback is used, the seal coat must be allowed to cure for a minimum of seven days. Otherwise, the diesel in the cutback will soften the asphalt binder in the HMA overlay.<br />
<br />
===409.2.6 Traffic Control (Sec 409.6)===<br />
See [[460.6 Paving Operations|Traffic Control]] in Paving Operations. Otherwise, the diesel used<br />
in the production of the cutback will degrade the binder in the subsequently placed HMA overlay.<br />
<br />
===409.2.7 Basis of Acceptance (Sec 409.7)===<br />
The criteria outlined in Standard Specification Section 409.7 must be met prior to acceptance<br />
of the project. The following items are suggestions for an acceptable project:<br />
<br />
:(1) Route trucks onto the project in such a manner that they will not have to turn on the newly spread aggregate.<br />
:(2) Keep the distributor and the aggregate spreader within approximately 30 seconds of each another (220 ft. at 5 mph).<br />
:(3) Construct transverse joints with building paper that is held securely in place.<br />
:(4) Construct longitudinal joints with a slight overlap so that a gap between the applications is avoided. The joint should be located near the lane line.<br />
:(5) Operate the distributor at a slow enough speed to ensure uniform spread and to reduced the elapsed time between the application of binder and aggregate.<br />
:(6) Use a shield on the outside end of the spray bar on the first of two adjacent spreads, and on both ends on the final passes, to prevent tapering of binder spread where aggregate will not adhere.<br />
:(7) Operate the distributor and the aggregate spreader at approximately equal speeds with a minimum distance between them.<br />
:(8) If necessary, patching, brooming, and/or salvaging should be performed immediately behind the aggregate spreader.<br />
:(9) On superelevated sections, the length of the binder application may need to be reduced in order to minimize the transverse flow of the binder before the application of cover the aggregate.<br />
<br />
==409.3 Materials Inspection for Sec 409==<br />
<br />
===409.3.1 Procedure===<br />
<br />
====409.3.1.1 Mix Design Procedure====<br />
<br />
In order for a seal coat mix design to be approved, the contractor’s proposed job mix formula (JMF) shall be submitted as required in [[#409.2.3 Report|Report]]. Trial mix samples will not be required unless requested by the Field Office. If requested, trial mix samples, along with samples of asphalt binder, must be obtained and submitted to the Central Laboratory in accordance with [[:Category:1001 General Requirements for Material|EPG 1001 General Requirements for Material]]. When possible, the JMF and correspondence should be transmitted electronically. The Materials Field Office e-mail address is "mfo".<br />
<br />
====409.3.1.2 District Procedure====<br />
<br />
When a proposed mix design has been received by the District, as required by the Standard Specifications, the District shall check the calculations thoroughly and ensure that the materials listed and sieve analyses shown are correct and that the proposed mixture components and proportions comply with Specifications. It may be necessary for the District to advise the contractor to make changes in the proposed mixture in order to fully comply with Department policies. When the District is satisfied that a proposed mixture is acceptable, a copy of the formula and the contractor's letter shall be submitted to the Materials Field Office, accompanied by a letter of transmittal with comments, any corrections made and recommendations. The letter shall contain the following information:<br />
:Project information – Job Number, Route, County, Contract Number.<br />
:Grade and Source of Asphalt Binder<br />
:Letting Date<br />
:Proposed Work – Type of Seal Coat, Job Location and Length<br />
:Annual Average Daily Traffic (AADT)<br />
:Mix Use – Mainline, Shoulders, etc.<br />
:Quantity of Mix<br />
<br />
Included in the letter should be information regarding the approximate date on which the contractor intends to begin placing the mixture on the roadway.<br />
<br />
====409.3.1.3 Field Office Procedure====<br />
<br />
The Materials Field Office is charged with the responsibility for processing the mix design. General procedures for processing a seal coat mix design are as follows:<br />
<br />
:a. A letter from a District requesting a mix with a copy of the contractor's formula and letter attached is received.<br />
<br />
:b. Contract specifications for the project are checked for necessary items.<br />
<br />
:c. Grade of asphalt as well as the refinery to be used and percent asphalt recommended are reviewed.<br />
<br />
:d. Gradation of the aggregate is checked for specification compliance and compared with the gradation determined by the Laboratory.<br />
<br />
:e. All calculations on the proposed job mix are checked.<br />
<br />
===409.3.2 Report===<br />
A letter of transmittal will accompany the approved mixture to the District Construction and Materials Engineer with distribution as follows:<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|-<br />
!style="background:#BEBEBE"|Title||style="background:#BEBEBE"|Copy of Transmittal Letter and Approved Mix<br />
|-<br />
| District Construction and Materials Engineer || 1 <br />
|-<br />
|Project Operations Clerk|| 1<br />
|-<br />
|Resident Engineer|| 1<br />
|-<br />
|Field Office File|| 1<br />
|}<br />
<br />
The letter of transmittal and the approved mixture will be sent by electronic mail to the individuals listed above.<br />
<br />
A copy of the approved formula accompanied by a letter of transmittal from the District Construction and Materials Engineer is to be forwarded to the contractor.<br />
<br />
==409.4 Maintenance Seal Coat/Chip Seals==<br />
Seal coats/chip seals have traditionally been used on lower volume roads because of vehicle windshield damage caused by the loose aggregate that remained on the roadway surface. However, with improvements of the bituminous binder, proper design and construction procedures the loose aggregate can be minimized. The small details are very important with the application of a chip seal. Chip seals should be restricted to 2-lane, 2-way roads with less than 3,500 vehicles per day, and 2-lane, one-way roads with less than 14,000 vehicles per day (7,000 vpd 1-way).<br />
<br />
Maintenance seal coat/chip sealing shall not be done on asphaltic concrete pavements unless approved by the Maintenance Division or unless the asphaltic concrete section has been downgraded to a service road, supplementary road, etc., carrying low volumes of traffic. If leveling of the surface or increased stability is needed, consideration should be given to the placement of a leveling course or mat. Continuous seal coat/chip seals are recommended only for level, even, and stable surfaces, preferably with an appreciable base, as a seal coat/chip seal in itself is not intended to increase the strength of the roadway. All seal coat/chip sealing should be done when weather and surface conditions are right and this definitely applies to continuous seal coat/chip seals and seal coat/chip seals on bridges. The roadway surface should be dry, humidity low, and it should not be done when precipitation is imminent. Temperatures should be warm but not extremely hot.<br />
<br />
Seal coat/chip seals require proper design, adequate supervision and inspection to obtain good results.<br />
<br />
===409.4.1 Seal Coat/Chip Seal Considerations===<br />
The type and grade of asphalt, specification of cover aggregate and the rate of application of the asphalt and aggregate should be carefully determined. The condition of the surface to be treated and the type and specific weight of the aggregate should also be considered during the design of the seal coat.<br />
<br />
Adjustments should be made in the field if necessary to obtain proper results. Recommendations as to equipment, materials, construction procedures and traffic control for continuous seal coat/chip seals are as follows: Also listed are some types of failures and their causes.<br />
<br />
1. Normally CRS-2 emulsified asphalt or penetration asphalt is used. Rates of application of the asphalt may vary from .20 to .40 gallon per square yard dependent on the condition of the surface to be treated, the type and grade of asphalt and the specification of the cover aggregate, 0.3 gallon per square yard is the normal rate. The rate for the asphalt should be such that the aggregate is embedded approximately 70% in the cured asphalt.<br />
<br />
2. Bituminous distributors used for seal coat/chip seal coat work should be operating properly and should be equipped with the necessary controls to ensure proper application of the asphalt. Pull type distributors are not to be used for major or continuous seal coat/chip seal work. The application rate for a bituminous distributor with a positive displacement pump is a function of the spray bar length in feet, the pump discharge in gallons per minute, and the distributor speed in feet per minute. The normal spray bar "factor or pump discharge is 10 to 15 gallons per spray bar foot of length for 1/8 in. nozzles spaced 4 in. apart. Center to center spacing on the spray bar is now almost universally 4 in. apart although some older models still have a 6 in. spacing of nozzles. For distributors equipped with different size nozzles spacing consult the manufacturers recommendations. Spray bar nozzles are to be clean and adjusted so that the solid fan patterns do not interfere with or distort each other. Normally each slit opening of the nozzle is adjusted to a 15 to 30 degree angle with the spray bar centerline. A 30 degree setting will allow passage of air currents without undue distortion to the fan pattern.<br />
<br />
3. The spray bar height setting is especially important for several reasons. It should be set at a minimum height to reduce blotches and voids caused by air turbulence. All distributors with four inch nozzle spacing must be set at a height which provides an exact triple coverage and all distributors with six inch nozzle spacing must be set for a height which provides an exact double coverage fan pattern. If the spray bar height is set higher than that needed to obtain the double or triple coverage, voids or ridges will result. The proper spray bar height for triple coverage can visually be checked before use by using the asphalt material specified at normal spray temperature and pressure by closing the second and third, fifth and sixth, eighth and ninth, etc., nozzles of the center section only of the spray bar, and adjusting the bar height until perfect single coverage is obtained. Double lap coverage involves the same procedure as above except every other nozzle is left open. If the distributor has already been checked for double lap coverage, increasing the spray height 50% will give triple coverage. These tests should be run on a clean, damp, dust free surface for good observation. The rear springs of the distributor are to be chained down to the rear axle under full load to prevent a change in spray bar height as the load is emptied.<br />
<br />
4. The cover aggregate shall meet Standard Specifications for seal coat/chip seal coat aggregate. Expanded shale, Iron Mountain chat or similar hard angular aggregate may be used on medium and heavy traffic asphaltic concrete surfaces. The rate of application of cover aggregate will depend on the specific roadway application. The amount of material may vary between 25 to 30 pounds per square yard and the specific weights of the material used for cover should be considered in determining this rate and also the type and grade of asphalt used. There are certain aggregates that are so ionized that they will not adhere to the asphalt District Materials personnel should be consulted regarding the aggregate and the asphalt that is to be used. The aggregate should be as free of moisture as possible, but normally this cannot be accomplished without excessive costs and usually the moisture present will not affect the adhesion.<br />
<br />
5. The cover aggregate is to be applied with an approved mechanical spreader, at an even rate. Mechanical spreader types are wheeled box type spreaders and self-propelled spreaders. The wheeled box type and self-propelled spreader require special truck hitches. The self-propelled spreader provides for very close control over the application rate of the aggregate and also has a sloped screen attachment that allows the larger aggregate to be deposited on the fresh film of asphalt first. Operators of spreaders and supply trucks must be familiar with and efficient in the operation of their units prior to the start of operations. Self-propelled 5 to 8 ton steel wheel rollers and pneumatic tired rollers are used for rolling on continuous seal coat/chip seals. Light rollers are used since only one layer of aggregate is involved and heavier rollers will crush softer aggregates. Pneumatic tired rollers are necessary due to the unevenness of most roadway surfaces. On spot seal coat/chip seal work, rolling is accomplished with truck tires and pull type steel wheel rollers.<br />
<br />
6. The following construction procedures are ideal and should be followed as closely as possible on major seal coat/chip seal jobs especially on bridge floors, high type pavements and where traffic volumes are heavy. The preparation of all surfaces to be seal coat/chip sealed is of utmost importance especially on bridge floors. Surfaces should be clean and free of loose aggregate. All necessary patching, removal of corrugations, etc. is to be accomplished prior to sealing. Old seal coat/chip seals or patches which may cause bleeding or failure on the new seal coat/chip seal cost should be removed. On shoulder work any necessary wedging and edge joint pouring should be done prior to sealing.<br />
<br />
7. The recommended spray temperature of the asphalt is to be maintained by reheating if necessary to provide for a uniform application. This is more critical with penetration asphalt than with cut-backs. The standard specifications should be consulted for the correct spraying temperatures. The asphalt application should be such that it may be covered with aggregate immediately. This is also more critical with penetration asphalt. With self-propelled spreaders, it is usually easy to accomplish. With other spreaders, the amount of asphalt applied should be controlled to that which can be covered immediately. This applies to spot seal coat/chip sealing as well as continuous seal coat/chip seals. Building paper is to be used at transverse joints to prevent unsightly and bumpy joints. Care should also be exercised by distributor operators to prevent overlapping at the longitudinal joints. The design of the spray bar allows for overlap at the longitudinal joint.<br />
<br />
8. Dry aggregate will provide best results under all conditions except when an emulsion asphalt is used but is not always possible. A slight amount of moisture on a dry, warm day will usually not cause any trouble. On bridge floors or high type pavement where traffic volumes are heavy, it may be practical to dry the material prior to application. Drying aggregate on a mixing board has proved to be practical in some areas. The cover aggregate is to be spread uniformly and as close to the design quantity as possible. Insufficient cover will lead to bleeding while excess aggregate will have a tendency to pull embedded aggregate loose under traffic conditions. A self-propelled spreader will provide best results. If a wheeled box type spreader is used the supply trucks should be operated by drivers who are proficient on this operation.<br />
<br />
9. Any brooming with a pull broom after the embedded aggregate is set must be supervised closely and confined to the cooler hours of the day. Only enough pressure should be applied to remove excess aggregate. Any objectionable, loose aggregate which develops after the section is opened to traffic should be broomed off to prevent damage to vehicles. Any excess aggregate left along the edge of bridge floors is to be removed as soon as possible.<br />
<br />
10. Rolling should begin immediately after the cover aggregate is applied. Rolling with a steel wheel roller is to be confined to one pass. At least two complete passes with pneumatic tired roller should be accomplished prior to opening to traffic. The recommended sequence of rolling is two complete passes with the pneumatic tired roller and then one complete pass with a steel wheel roller. On spot seal coat/chip sealing, rolling is done with a steel wheel roller and truck tires.<br />
<br />
===409.4.2 Traffic Control Considerations===<br />
Proper traffic control is of utmost importance in obtaining good results on any seal coat/chip seal work and cannot be stressed too strongly. The degree of controls is dependent to some extent on the type and grade of asphalt, weather conditions, traffic density and traffic speed. After rolling is completed traffic will not normally damage a seal coat/chip seal if restricted to low speeds. The controls listed below are considered a minimum and must be followed as closely as possible.<br />
<br />
1. Signing and traffic control devices are to be in accordance with the [[616.23 Traffic Control for Field Operations|Traffic Control for Field Operations]], and are to be in place as long as any hazards, such as loose aggregate on the traveled surface exists. On extremely heavy traffic sections, it may be necessary to request some assistance from the State Highway Patrol during peak hours of traffic. Adequate warning signs and flagging must be provided on any section where lanes are barricaded overnight.<br />
<br />
2. On continuous seal coat/chip seals, no traffic is to be allowed on the seal until rolling is completed; then traffic is to be controlled by pilot vehicle at a maximum speed of 20 miles per hour for at least two hours before being opened fully to traffic. On sections with less than 250 AADT, this control by pilot vehicle may be reduced to one hour. On multi-lane pavements, where traffic is normally very high, it is recommended that no traffic be allowed on the seal coat/chip seal for a period of 4 to 8 hours or possibly overnight and then allowed to pass at 20 miles per hour for one hour before full opening. This control at restricted speeds will not only ensure a better seal coat/chip seal coat job but will also reduce the hazards to traffic from loose aggregate. On shorter sections of continuous seal coat/chip seal coats, such as on bridge floors, where a pilot vehicle would not be feasible, the traffic is to be restricted to the 20 miles per hour by flagging and it will probably be necessary to stop traffic from both directions to hold their speed to 20 miles per hour.<br />
<br />
3. Traffic control on spot seal work is usually not as critical as on continuous seal, but the proper flagging and signing to assure safety and to minimize the whipping off of aggregate by traffic must be used.<br />
<br />
===409.4.3 Chip Seal Failures===<br />
It would be extremely misleading to give the impression that all seal coat/chip seal jobs are successful even though proper materials are used. Failures do occur and the important thing is to know why they occur and how to prevent them.<br />
<br />
1. Streaking results when alternate longitudinal strips of the seal coat/chip seal contain different quantities of asphalt binder. This is due to lack of uniformity of application. Some of the more common causes of streaking are mechanical faults, improper spray bar adjustment, and careless operation of distributors. Another frequent cause is applying the asphalt at a temperature so low that it is not fluid enough to fan out properly from the nozzles on the spray bars. Streaking can generally be avoided by using a clean and properly adjusted distributor and applying the asphalt at the correct temperature. Careful spray bar adjustment is important to prevent streaking when high viscosity materials are used.<br />
<br />
2. The use of too much asphalt in seal coat/chip seal work is a common fault as well as a serious one because of the safety hazard it presents. Excess asphalt works upward onto the pavement surface and is the origin of the black and sticky surface condition referred to as flushing, bleeding, fattening up, etc., which becomes slippery to traffic in wet weather. It should be pointed out that a black appearance can also be caused by insufficient cover aggregate or may in part, be due to loss of a portion of cover aggregate.<br />
<br />
3. The application of insufficient asphalt binder leads to loss of cover aggregate because not enough binder has been applied to cement the aggregate particles into place. Generally, the use of too little asphalt occurs less frequently than the application of too much. This emphasizes the need for very careful attention to proper application quantities.<br />
<br />
4. The major causes for loss of cover aggregate are insufficient asphalt, dirty or dust covered aggregate, or permitting fast traffic on the road before the seal coat/chip seal has cured. If there is a long delay between spraying the asphalt binder and spreading the cover aggregate, even during warm weather, the asphalt may become so cooled or hardened that good adhesion between the two is seriously impaired. This is especially true when cutback asphalts and asphalt cements are used for the binder. Field studies show that non-uniform asphalt application occurs most frequently during cool weather. The asphalt temperature drops to that of the pavement within approximately two minutes. For this reason weather and temperature limitations should be observed.<br />
<br />
5. The strength of a road section is analogous to the strength of a chain and its weakest link. Obviously, any seal coat/chip seal will fail if the supporting road structure cannot bear the traffic. Although a seal coat/chip seal must be tough and durable along with its other desirable characteristics, it is not generally considered a load bearing factor in the overall design. The subbase, base and surface courses are designed for this purpose. Seal coat/chip seals are not feasible for a road which has a soft or poor base or uneven surface. Also roadway surfaces which will require excessive spot sealing, patching or wedging should not be considered for seal coat/chip seals as these conditions will penetrate the seal coat/chip seal and cause bleeding and tracking of asphalt and possibly failure. Leveling courses or mats should be considered for surfaces such as the above. When a level, stable surface has been obtained a seal coat/chip seal may then be considered.<br />
<br />
===409.4.4 Maintenance Seal Coat/Chip Seal Design===<br />
Refer to [[Media:409 Minnesota Seal Coat Design.pdf|Chapter 4 of the Minnesota Seal Coat/Chip Seal Design Procedure]] regarding the proper procedures for designing a chip seal for a specific roadway application.<br />
<br />
==409.5 Maintenance Planning Guide==<br />
'''Printable''' [[media:R31C - Chip Sealing - Course Aggregate.pdf|'''Maintenance Planning Guide for Chip Sealing''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].</div>Jonesjbhttps://epg.modot.org/index.php?title=File:409_SEAL_COAT_MODOT_STRIPING.pdf&diff=34053File:409 SEAL COAT MODOT STRIPING.pdf2014-07-11T18:17:45Z<p>Jonesjb: </p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=File:409_JSP_07_2014.doc&diff=34052File:409 JSP 07 2014.doc2014-07-11T18:17:33Z<p>Jonesjb: </p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=File:409_FY2015_Contract_Seal_Coat_Guidelines.pdf&diff=34051File:409 FY2015 Contract Seal Coat Guidelines.pdf2014-07-11T18:17:10Z<p>Jonesjb: </p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=Category:409_Seal_Coat&diff=34050Category:409 Seal Coat2014-07-11T18:16:48Z<p>Jonesjb: </p>
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<div>[[image:409 Distributor Sealing Operation.jpg|right|400px|thumb|<center>'''Distributor sealing operation'''</center>]]<br />
Seal Coating or chip sealing is the application of a bituminous binder immediately followed by the application of an aggregate cover. The aggregate is then rolled to embed it into the binder. The desired functions of a seal coat/chip seal are:<br />
:1. Seal the road surface against the entrance of moisture and air.<br />
:2. Provide a new skid resistance wearing surface.<br />
:3. Rejuvenate or enliven a dry or weathered surface against abrasion and disintegration.<br />
:4. Reinforce and help restore design surface.<br />
:5. Provide a demarcation in texture between the road surface and the shoulders for traffic guidance.<br />
:6. Cover ragged patches and other discrepancies.<br />
<div id="Seal coats/chip seals"></div><br />
Seal coats/chip seals cannot be used to correct the pavement profile or correct a rough ride. When selecting a roadway for chip sealing, the existing pavement should exhibit a good cross section and a good base, and have a good ride quality. Working cracks should be sealed, and non-working cracks &ge; 3/8 in. wide should be filled prior to the placement of the chip seal (For more information on working and nonworking cracks see [[413.5 Crack Treatment in Bituminous Pavements|Crack Treatment in Bituminous Pavements]]).<br />
<br />
<br />
{|border="4" align="right" style="margin-left:10px"<br />
|-<br />
|style="background:#BEBEBE" align="center"|'''[[media:409_FY2015_Contract_Seal_Coat_Guidelines.pdf|Contract Seal Coat Guidelines]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center" | '''[[media:409_JSP_07_2014.doc|Job Special Provisions]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center"|''' [[media:409_SEAL_COAT_MODOT_STRIPING.pdf|PDFs of Contract Seal Coat Plan Templates]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center" width=400|Contact Bidding and Contract Services, Danica Stovall-Taylor, for additional guidance. <br />
|}<br />
<br />
==409.1 Design==<br />
In contracts using [http://modot.mo.gov/business/standards_and_specs/Sec0409.pdf Standard Specification Section 409], the type of bituminous material and grade of liquid asphalt is selected by the contractor. Differing aggregate qualities are available and specified according to the roadway traffic. Grade C is used only on roads with AADT < 750. Grade B is used on two-lane, two-way roads with AADT < 1700, and divided roads with AADT < 3500. Grade A is used on two-lane, two-way roads with AADT < 3500, and divided roads with AADT < 14,000. Grade C is used for all shoulder applications. To improve the perception of the driving public, Sec 409 requires the finished seal coat to have a dark appearance. See [[751.1 Preliminary Design#751.1.3.6 Asphalt Wearing Surface|EPG 751.1.3.6 Asphalt Wearing Surface]] for guidelines on aggregate grade selection for bridges.<br />
<br />
A seal coat placed on a porous surface such as an aggregate base should receive a [[:Category:408 Prime Coat|prime coat]].<br />
<br />
==409.2 Construction Inspection for Sec 409==<br />
===409.2.1 Description (Sec 409.1)===<br />
Seal coats, also known as chip seals, are used to lengthen the service life of an existing pavement by waterproofing it and improving its surface texture.<br />
<br />
===409.2.2 Material (Sec 409.2)===<br />
See also [[:Category:1003 Aggregate for Seal Coats|1003 Aggregate for Seal Coats]] and [[:Category:1015 Bituminous Material|EPG 1015 Bituminous Material]].<br />
<br />
===409.2.3 Job Mix Formula (Sec 409.3)===<br />
Proper design of a seal coat consists of determining the proper rate of application for the<br />
bituminous material and cover aggregate. The mix design procedure will be in accordance with<br />
[[#409.2 Materials Inspection for Sec 409|Materials Inspection]].<br />
<br />
===409.2.4 Equipment (Sec 409.4)===<br />
See [[460.4 Paving Equipment|Distributor]] in Paving Equipment. A rotary power broom or vacuum sweeper will be used to remove excess loose aggregate. Pneumatic tire rollers will be used to embed the cover aggregate. The contact pressure of the tires shall be at least 80 psi. In order to achieve the required contact pressure, the contractor may need to adjust the inflation pressure of the tires.<br />
<br />
===409.2.5 Construction Requirements (Sec 409.5)===<br />
<br />
'''Weather Limitations''' (Sec 409.5.2)<br />
<br />
See [[460.6 Paving Operations#460.6.3 Weather Conditions|Weather Conditions]] in Paving Operations.<br />
<br />
'''Application of Bituminous Material''' (Sec 409.5.4)<br />
<br />
See [[460.4 Paving Equipment|Distributor]] in Paving Equipment. Excess binder works upward to the surface of the pavement and creates a black, sticky surface condition (i.e., flushing, bleeding, etc.). In wet weather, the surface may become slippery. A black appearance in the surface can also be the result of insufficient cover aggregate or a loss of cover aggregate.<br />
<br />
Applying too little binder to the surface leads to a loss of cover aggregate because insufficient binder is present to hold the aggregate in place. Generally, the use of too little binder occurs less frequently than the use of too much.<br />
<br />
'''Application of Cover Aggregate''' (Sec 409.5.5)<br />
<br />
Cover aggregate is applied with a self-propelled spreader. Aggregate spreading should progress rapidly as a continuous operation. Stopping and starting of the distributor and/or aggregate spreader should be held to a minimum. The operation shall proceed in such a manner that the binder will not be permitted to cool, set up, dry or otherwise impair retention of the cover aggregate. To achieve this, the maximum time interval between applying the binder and spreading the cover aggregate should be limited to 30 seconds.<br />
<br />
Any deficiencies in application of cover aggregate resulting in uncovered areas or nonuniform<br />
application of aggregate should be immediately corrected behind the spreading equipment. Any excess aggregate should be removed immediately to avoid damage to the seal coat and possible build up of materials, which could adversely affect the ride quality. Pull brooms or drags should not be used to distribute cover aggregate until embedded aggregate is set. If dust is a nuisance or impairs visibility, the contractor will be required to pre-coat the aggregate.<br />
<br />
The rolling operation should immediately follow spreading to embed the aggregate while the binder is still soft and tacky. Pneumatic tired rollers must be operated slow enough to prevent<br />
the tires from displacing or picking up aggregate. All rolling must be completed the same day that the binder and aggregate have been applied. All loose aggregate must be removed before the<br />
roadway is opened to traffic.<br />
<br />
The major causes of loss of cover aggregate are insufficient binder, dirty or dust covered aggregate, or opening the roadway to traffic before the seal coat has cured. If there is a long delay between the application of the binder and the cover aggregate, even during warm weather, the binder may cool and harden and good adhesion is seriously impaired.<br />
<br />
:Sec 409.5.5.1 If required by the contract, a seal coat may be applied to a bridge deck before a new hot-mix asphalt (HMA) surface is placed using the following guidelines. If an emulsion is used in the seal coat, the HMA surface may be placed in the same day. However, the haul trucks must not be allowed to make turning movements on the fresh seal coat application so that displacement of the cover aggregate does not occur. If a cutback is used, the seal coat must be allowed to cure for a minimum of seven days. Otherwise, the diesel in the cutback will soften the asphalt binder in the HMA overlay.<br />
<br />
===409.2.6 Traffic Control (Sec 409.6)===<br />
See [[460.6 Paving Operations|Traffic Control]] in Paving Operations. Otherwise, the diesel used<br />
in the production of the cutback will degrade the binder in the subsequently placed HMA overlay.<br />
<br />
===409.2.7 Basis of Acceptance (Sec 409.7)===<br />
The criteria outlined in Standard Specification Section 409.7 must be met prior to acceptance<br />
of the project. The following items are suggestions for an acceptable project:<br />
<br />
:(1) Route trucks onto the project in such a manner that they will not have to turn on the newly spread aggregate.<br />
:(2) Keep the distributor and the aggregate spreader within approximately 30 seconds of each another (220 ft. at 5 mph).<br />
:(3) Construct transverse joints with building paper that is held securely in place.<br />
:(4) Construct longitudinal joints with a slight overlap so that a gap between the applications is avoided. The joint should be located near the lane line.<br />
:(5) Operate the distributor at a slow enough speed to ensure uniform spread and to reduced the elapsed time between the application of binder and aggregate.<br />
:(6) Use a shield on the outside end of the spray bar on the first of two adjacent spreads, and on both ends on the final passes, to prevent tapering of binder spread where aggregate will not adhere.<br />
:(7) Operate the distributor and the aggregate spreader at approximately equal speeds with a minimum distance between them.<br />
:(8) If necessary, patching, brooming, and/or salvaging should be performed immediately behind the aggregate spreader.<br />
:(9) On superelevated sections, the length of the binder application may need to be reduced in order to minimize the transverse flow of the binder before the application of cover the aggregate.<br />
<br />
==409.3 Materials Inspection for Sec 409==<br />
<br />
===409.3.1 Procedure===<br />
<br />
====409.3.1.1 Mix Design Procedure====<br />
<br />
In order for a seal coat mix design to be approved, the contractor’s proposed job mix formula (JMF) shall be submitted as required in [[#409.2.3 Report|Report]]. Trial mix samples will not be required unless requested by the Field Office. If requested, trial mix samples, along with samples of asphalt binder, must be obtained and submitted to the Central Laboratory in accordance with [[:Category:1001 General Requirements for Material|EPG 1001 General Requirements for Material]]. When possible, the JMF and correspondence should be transmitted electronically. The Materials Field Office e-mail address is "mfo".<br />
<br />
====409.3.1.2 District Procedure====<br />
<br />
When a proposed mix design has been received by the District, as required by the Standard Specifications, the District shall check the calculations thoroughly and ensure that the materials listed and sieve analyses shown are correct and that the proposed mixture components and proportions comply with Specifications. It may be necessary for the District to advise the contractor to make changes in the proposed mixture in order to fully comply with Department policies. When the District is satisfied that a proposed mixture is acceptable, a copy of the formula and the contractor's letter shall be submitted to the Materials Field Office, accompanied by a letter of transmittal with comments, any corrections made and recommendations. The letter shall contain the following information:<br />
:Project information – Job Number, Route, County, Contract Number.<br />
:Grade and Source of Asphalt Binder<br />
:Letting Date<br />
:Proposed Work – Type of Seal Coat, Job Location and Length<br />
:Annual Average Daily Traffic (AADT)<br />
:Mix Use – Mainline, Shoulders, etc.<br />
:Quantity of Mix<br />
<br />
Included in the letter should be information regarding the approximate date on which the contractor intends to begin placing the mixture on the roadway.<br />
<br />
====409.3.1.3 Field Office Procedure====<br />
<br />
The Materials Field Office is charged with the responsibility for processing the mix design. General procedures for processing a seal coat mix design are as follows:<br />
<br />
:a. A letter from a District requesting a mix with a copy of the contractor's formula and letter attached is received.<br />
<br />
:b. Contract specifications for the project are checked for necessary items.<br />
<br />
:c. Grade of asphalt as well as the refinery to be used and percent asphalt recommended are reviewed.<br />
<br />
:d. Gradation of the aggregate is checked for specification compliance and compared with the gradation determined by the Laboratory.<br />
<br />
:e. All calculations on the proposed job mix are checked.<br />
<br />
===409.3.2 Report===<br />
A letter of transmittal will accompany the approved mixture to the District Construction and Materials Engineer with distribution as follows:<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|-<br />
!style="background:#BEBEBE"|Title||style="background:#BEBEBE"|Copy of Transmittal Letter and Approved Mix<br />
|-<br />
| District Construction and Materials Engineer || 1 <br />
|-<br />
|Project Operations Clerk|| 1<br />
|-<br />
|Resident Engineer|| 1<br />
|-<br />
|Field Office File|| 1<br />
|}<br />
<br />
The letter of transmittal and the approved mixture will be sent by electronic mail to the individuals listed above.<br />
<br />
A copy of the approved formula accompanied by a letter of transmittal from the District Construction and Materials Engineer is to be forwarded to the contractor.<br />
<br />
==409.4 Maintenance Seal Coat/Chip Seals==<br />
Seal coats/chip seals have traditionally been used on lower volume roads because of vehicle windshield damage caused by the loose aggregate that remained on the roadway surface. However, with improvements of the bituminous binder, proper design and construction procedures the loose aggregate can be minimized. The small details are very important with the application of a chip seal. Chip seals should be restricted to 2-lane, 2-way roads with less than 3,500 vehicles per day, and 2-lane, one-way roads with less than 14,000 vehicles per day (7,000 vpd 1-way).<br />
<br />
Maintenance seal coat/chip sealing shall not be done on asphaltic concrete pavements unless approved by the Maintenance Division or unless the asphaltic concrete section has been downgraded to a service road, supplementary road, etc., carrying low volumes of traffic. If leveling of the surface or increased stability is needed, consideration should be given to the placement of a leveling course or mat. Continuous seal coat/chip seals are recommended only for level, even, and stable surfaces, preferably with an appreciable base, as a seal coat/chip seal in itself is not intended to increase the strength of the roadway. All seal coat/chip sealing should be done when weather and surface conditions are right and this definitely applies to continuous seal coat/chip seals and seal coat/chip seals on bridges. The roadway surface should be dry, humidity low, and it should not be done when precipitation is imminent. Temperatures should be warm but not extremely hot.<br />
<br />
Seal coat/chip seals require proper design, adequate supervision and inspection to obtain good results.<br />
<br />
===409.4.1 Seal Coat/Chip Seal Considerations===<br />
The type and grade of asphalt, specification of cover aggregate and the rate of application of the asphalt and aggregate should be carefully determined. The condition of the surface to be treated and the type and specific weight of the aggregate should also be considered during the design of the seal coat.<br />
<br />
Adjustments should be made in the field if necessary to obtain proper results. Recommendations as to equipment, materials, construction procedures and traffic control for continuous seal coat/chip seals are as follows: Also listed are some types of failures and their causes.<br />
<br />
1. Normally CRS-2 emulsified asphalt or penetration asphalt is used. Rates of application of the asphalt may vary from .20 to .40 gallon per square yard dependent on the condition of the surface to be treated, the type and grade of asphalt and the specification of the cover aggregate, 0.3 gallon per square yard is the normal rate. The rate for the asphalt should be such that the aggregate is embedded approximately 70% in the cured asphalt.<br />
<br />
2. Bituminous distributors used for seal coat/chip seal coat work should be operating properly and should be equipped with the necessary controls to ensure proper application of the asphalt. Pull type distributors are not to be used for major or continuous seal coat/chip seal work. The application rate for a bituminous distributor with a positive displacement pump is a function of the spray bar length in feet, the pump discharge in gallons per minute, and the distributor speed in feet per minute. The normal spray bar "factor or pump discharge is 10 to 15 gallons per spray bar foot of length for 1/8 in. nozzles spaced 4 in. apart. Center to center spacing on the spray bar is now almost universally 4 in. apart although some older models still have a 6 in. spacing of nozzles. For distributors equipped with different size nozzles spacing consult the manufacturers recommendations. Spray bar nozzles are to be clean and adjusted so that the solid fan patterns do not interfere with or distort each other. Normally each slit opening of the nozzle is adjusted to a 15 to 30 degree angle with the spray bar centerline. A 30 degree setting will allow passage of air currents without undue distortion to the fan pattern.<br />
<br />
3. The spray bar height setting is especially important for several reasons. It should be set at a minimum height to reduce blotches and voids caused by air turbulence. All distributors with four inch nozzle spacing must be set at a height which provides an exact triple coverage and all distributors with six inch nozzle spacing must be set for a height which provides an exact double coverage fan pattern. If the spray bar height is set higher than that needed to obtain the double or triple coverage, voids or ridges will result. The proper spray bar height for triple coverage can visually be checked before use by using the asphalt material specified at normal spray temperature and pressure by closing the second and third, fifth and sixth, eighth and ninth, etc., nozzles of the center section only of the spray bar, and adjusting the bar height until perfect single coverage is obtained. Double lap coverage involves the same procedure as above except every other nozzle is left open. If the distributor has already been checked for double lap coverage, increasing the spray height 50% will give triple coverage. These tests should be run on a clean, damp, dust free surface for good observation. The rear springs of the distributor are to be chained down to the rear axle under full load to prevent a change in spray bar height as the load is emptied.<br />
<br />
4. The cover aggregate shall meet Standard Specifications for seal coat/chip seal coat aggregate. Expanded shale, Iron Mountain chat or similar hard angular aggregate may be used on medium and heavy traffic asphaltic concrete surfaces. The rate of application of cover aggregate will depend on the specific roadway application. The amount of material may vary between 25 to 30 pounds per square yard and the specific weights of the material used for cover should be considered in determining this rate and also the type and grade of asphalt used. There are certain aggregates that are so ionized that they will not adhere to the asphalt District Materials personnel should be consulted regarding the aggregate and the asphalt that is to be used. The aggregate should be as free of moisture as possible, but normally this cannot be accomplished without excessive costs and usually the moisture present will not affect the adhesion.<br />
<br />
5. The cover aggregate is to be applied with an approved mechanical spreader, at an even rate. Mechanical spreader types are wheeled box type spreaders and self-propelled spreaders. The wheeled box type and self-propelled spreader require special truck hitches. The self-propelled spreader provides for very close control over the application rate of the aggregate and also has a sloped screen attachment that allows the larger aggregate to be deposited on the fresh film of asphalt first. Operators of spreaders and supply trucks must be familiar with and efficient in the operation of their units prior to the start of operations. Self-propelled 5 to 8 ton steel wheel rollers and pneumatic tired rollers are used for rolling on continuous seal coat/chip seals. Light rollers are used since only one layer of aggregate is involved and heavier rollers will crush softer aggregates. Pneumatic tired rollers are necessary due to the unevenness of most roadway surfaces. On spot seal coat/chip seal work, rolling is accomplished with truck tires and pull type steel wheel rollers.<br />
<br />
6. The following construction procedures are ideal and should be followed as closely as possible on major seal coat/chip seal jobs especially on bridge floors, high type pavements and where traffic volumes are heavy. The preparation of all surfaces to be seal coat/chip sealed is of utmost importance especially on bridge floors. Surfaces should be clean and free of loose aggregate. All necessary patching, removal of corrugations, etc. is to be accomplished prior to sealing. Old seal coat/chip seals or patches which may cause bleeding or failure on the new seal coat/chip seal cost should be removed. On shoulder work any necessary wedging and edge joint pouring should be done prior to sealing.<br />
<br />
7. The recommended spray temperature of the asphalt is to be maintained by reheating if necessary to provide for a uniform application. This is more critical with penetration asphalt than with cut-backs. The standard specifications should be consulted for the correct spraying temperatures. The asphalt application should be such that it may be covered with aggregate immediately. This is also more critical with penetration asphalt. With self-propelled spreaders, it is usually easy to accomplish. With other spreaders, the amount of asphalt applied should be controlled to that which can be covered immediately. This applies to spot seal coat/chip sealing as well as continuous seal coat/chip seals. Building paper is to be used at transverse joints to prevent unsightly and bumpy joints. Care should also be exercised by distributor operators to prevent overlapping at the longitudinal joints. The design of the spray bar allows for overlap at the longitudinal joint.<br />
<br />
8. Dry aggregate will provide best results under all conditions except when an emulsion asphalt is used but is not always possible. A slight amount of moisture on a dry, warm day will usually not cause any trouble. On bridge floors or high type pavement where traffic volumes are heavy, it may be practical to dry the material prior to application. Drying aggregate on a mixing board has proved to be practical in some areas. The cover aggregate is to be spread uniformly and as close to the design quantity as possible. Insufficient cover will lead to bleeding while excess aggregate will have a tendency to pull embedded aggregate loose under traffic conditions. A self-propelled spreader will provide best results. If a wheeled box type spreader is used the supply trucks should be operated by drivers who are proficient on this operation.<br />
<br />
9. Any brooming with a pull broom after the embedded aggregate is set must be supervised closely and confined to the cooler hours of the day. Only enough pressure should be applied to remove excess aggregate. Any objectionable, loose aggregate which develops after the section is opened to traffic should be broomed off to prevent damage to vehicles. Any excess aggregate left along the edge of bridge floors is to be removed as soon as possible.<br />
<br />
10. Rolling should begin immediately after the cover aggregate is applied. Rolling with a steel wheel roller is to be confined to one pass. At least two complete passes with pneumatic tired roller should be accomplished prior to opening to traffic. The recommended sequence of rolling is two complete passes with the pneumatic tired roller and then one complete pass with a steel wheel roller. On spot seal coat/chip sealing, rolling is done with a steel wheel roller and truck tires.<br />
<br />
===409.4.2 Traffic Control Considerations===<br />
Proper traffic control is of utmost importance in obtaining good results on any seal coat/chip seal work and cannot be stressed too strongly. The degree of controls is dependent to some extent on the type and grade of asphalt, weather conditions, traffic density and traffic speed. After rolling is completed traffic will not normally damage a seal coat/chip seal if restricted to low speeds. The controls listed below are considered a minimum and must be followed as closely as possible.<br />
<br />
1. Signing and traffic control devices are to be in accordance with the [[616.23 Traffic Control for Field Operations|Traffic Control for Field Operations]], and are to be in place as long as any hazards, such as loose aggregate on the traveled surface exists. On extremely heavy traffic sections, it may be necessary to request some assistance from the State Highway Patrol during peak hours of traffic. Adequate warning signs and flagging must be provided on any section where lanes are barricaded overnight.<br />
<br />
2. On continuous seal coat/chip seals, no traffic is to be allowed on the seal until rolling is completed; then traffic is to be controlled by pilot vehicle at a maximum speed of 20 miles per hour for at least two hours before being opened fully to traffic. On sections with less than 250 AADT, this control by pilot vehicle may be reduced to one hour. On multi-lane pavements, where traffic is normally very high, it is recommended that no traffic be allowed on the seal coat/chip seal for a period of 4 to 8 hours or possibly overnight and then allowed to pass at 20 miles per hour for one hour before full opening. This control at restricted speeds will not only ensure a better seal coat/chip seal coat job but will also reduce the hazards to traffic from loose aggregate. On shorter sections of continuous seal coat/chip seal coats, such as on bridge floors, where a pilot vehicle would not be feasible, the traffic is to be restricted to the 20 miles per hour by flagging and it will probably be necessary to stop traffic from both directions to hold their speed to 20 miles per hour.<br />
<br />
3. Traffic control on spot seal work is usually not as critical as on continuous seal, but the proper flagging and signing to assure safety and to minimize the whipping off of aggregate by traffic must be used.<br />
<br />
===409.4.3 Chip Seal Failures===<br />
It would be extremely misleading to give the impression that all seal coat/chip seal jobs are successful even though proper materials are used. Failures do occur and the important thing is to know why they occur and how to prevent them.<br />
<br />
1. Streaking results when alternate longitudinal strips of the seal coat/chip seal contain different quantities of asphalt binder. This is due to lack of uniformity of application. Some of the more common causes of streaking are mechanical faults, improper spray bar adjustment, and careless operation of distributors. Another frequent cause is applying the asphalt at a temperature so low that it is not fluid enough to fan out properly from the nozzles on the spray bars. Streaking can generally be avoided by using a clean and properly adjusted distributor and applying the asphalt at the correct temperature. Careful spray bar adjustment is important to prevent streaking when high viscosity materials are used.<br />
<br />
2. The use of too much asphalt in seal coat/chip seal work is a common fault as well as a serious one because of the safety hazard it presents. Excess asphalt works upward onto the pavement surface and is the origin of the black and sticky surface condition referred to as flushing, bleeding, fattening up, etc., which becomes slippery to traffic in wet weather. It should be pointed out that a black appearance can also be caused by insufficient cover aggregate or may in part, be due to loss of a portion of cover aggregate.<br />
<br />
3. The application of insufficient asphalt binder leads to loss of cover aggregate because not enough binder has been applied to cement the aggregate particles into place. Generally, the use of too little asphalt occurs less frequently than the application of too much. This emphasizes the need for very careful attention to proper application quantities.<br />
<br />
4. The major causes for loss of cover aggregate are insufficient asphalt, dirty or dust covered aggregate, or permitting fast traffic on the road before the seal coat/chip seal has cured. If there is a long delay between spraying the asphalt binder and spreading the cover aggregate, even during warm weather, the asphalt may become so cooled or hardened that good adhesion between the two is seriously impaired. This is especially true when cutback asphalts and asphalt cements are used for the binder. Field studies show that non-uniform asphalt application occurs most frequently during cool weather. The asphalt temperature drops to that of the pavement within approximately two minutes. For this reason weather and temperature limitations should be observed.<br />
<br />
5. The strength of a road section is analogous to the strength of a chain and its weakest link. Obviously, any seal coat/chip seal will fail if the supporting road structure cannot bear the traffic. Although a seal coat/chip seal must be tough and durable along with its other desirable characteristics, it is not generally considered a load bearing factor in the overall design. The subbase, base and surface courses are designed for this purpose. Seal coat/chip seals are not feasible for a road which has a soft or poor base or uneven surface. Also roadway surfaces which will require excessive spot sealing, patching or wedging should not be considered for seal coat/chip seals as these conditions will penetrate the seal coat/chip seal and cause bleeding and tracking of asphalt and possibly failure. Leveling courses or mats should be considered for surfaces such as the above. When a level, stable surface has been obtained a seal coat/chip seal may then be considered.<br />
<br />
===409.4.4 Maintenance Seal Coat/Chip Seal Design===<br />
Refer to [[Media:409 Minnesota Seal Coat Design.pdf|Chapter 4 of the Minnesota Seal Coat/Chip Seal Design Procedure]] regarding the proper procedures for designing a chip seal for a specific roadway application.<br />
<br />
==409.5 Maintenance Planning Guide==<br />
'''Printable''' [[media:R31C - Chip Sealing - Course Aggregate.pdf|'''Maintenance Planning Guide for Chip Sealing''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].</div>Jonesjbhttps://epg.modot.org/index.php?title=File:402_FY2015_Contract_Leveling_Course_Guidelines.pdf&diff=34049File:402 FY2015 Contract Leveling Course Guidelines.pdf2014-07-11T18:09:20Z<p>Jonesjb: </p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=File:402_CLC_MODOT_STRIPE.pdf&diff=34048File:402 CLC MODOT STRIPE.pdf2014-07-11T18:07:14Z<p>Jonesjb: </p>
<hr />
<div></div>Jonesjbhttps://epg.modot.org/index.php?title=File:402_CLC_CONTRACTOR_STRIPE.pdf&diff=34047File:402 CLC CONTRACTOR STRIPE.pdf2014-07-11T18:06:57Z<p>Jonesjb: </p>
<hr />
<div></div>Jonesjbhttps://epg.modot.org/index.php?title=Category:402_Bituminous_Surface_Leveling&diff=34046Category:402 Bituminous Surface Leveling2014-07-11T18:06:34Z<p>Jonesjb: </p>
<hr />
<div>{|border="4" align="right"<br />
|-<br />
|style="background:#BEBEBE" align="center"|'''[[media:402 FY2015 Contract Leveling Course Guidelines.pdf|Contract Leveling Course Guidelines]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center" | '''[[media:402_JSP_FY15.doc|Job Special Provisions]]'''<br />
|-<br />
|style="background:#BEBEBE" align="center"|''' <div id="PDFs of Contract Leveling Course Plan Templates"></div>PDFs of Contract Leveling Course Plan Templates'''<br>[[media:402_CLC_CONTRACTOR_STRIPE.pdf|Contractor Striping]]<br>[[media:402_CLC_MODOT_STRIPE.pdf|MoDOT Striping]]<br />
|}<br />
<br />
==402.1 Design of Contract Leveling Course Projects==<br />
<br />
{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right" <br />
|- <br />
|'''Figures'''<br />
|-<br />
|[[Media:Asphalt Cement Price Index Example Calculations.pdf|Asphalt Cement Price Index Example Calculations]]<br />
|}<br />
===402.1.1 Plan Preparation===<br />
In order to coordinate and expedite the preparation of projects for the contract leveling course program, plans shall be prepared in English units and submitted to the Design Division by August 1 of the program year. This will enable the bidding and contract services section to adjust the groupings, if necessary, and to appropriately schedule the bid opening dates.<br />
<br />
The contract leveling course program is intended for use on roadways with less than 3500 AADT, and on which a BP-1, Type C, Type IC or superpave mixture has not been previously placed. Superpave resurfacing is viewed as more involved work, and should be programmed as a thin lift overlay project outside of the contract leveling course program.<br />
<br />
To shorten the processing time, improve the quality of plans and to standardize procedures across the state, the following should be used when preparing plans in English units:<br />
<br />
*No conceptual study report is necessary for contract leveling course projects, but the core team should give the corridor an elementary examination and document major safety or operational deficiencies. Unless there are very low-cost countermeasures available, the narrow scope of these projects will require that most remedial work be accomplished with maintenance forces or programmed<br />
into future projects.<br />
<br />
*Each project should have, as a minimum, the following plan sheets:<br />
<br />
:1. Title Sheet, with north arrow pointing to the top of the sheet, if possible.<br />
:2. Length of Project Sheet - should include "exceptions."<br />
:3. Typical Section Sheet - should include "estimate factors."<br />
<br />
*Leveling course projects must have logical termini. Do not break projects at district, county or city limit lines (short projects which abut should not be shown as separate projects). Coordination with adjoining districts should be done when a project abuts a district boundary.<br />
<br />
*[[#PDFs of Contract Leveling Course Plan Templates|Contract Leveling Course (CLC) Plan Templates]] provide sample templates for typical sections but not the location sketch or project length and typical sections. Examples of CLC plans are electronically available in Microstation format on district servers.<br />
<br />
*The Bridge Division will analyze all bridges within the project limits to determine which bridges can be overlayed based on bridge rail height and load rating. With supporting information from District Operations and/or Design, the Bridge Division will verify the load ratings for each bridge and verify that any standard rail will not be made substandard by the Contract Leveling Course operations. Bridges should be excepted unless prior written approval is obtained from the Bridge Division and submitted with the transmittal package.<br />
<br />
*Districts need to supply at time of submittal conflict of interest documentation (see [[237.9 Submission of Plans and Supporting Documents|Submission of Plans and Supporting Documents]]).<br />
<br />
*Use of district forces for any operation, such as milling, that may affect the progression of the contractor operation, shall be approved in accordance with [[646.4 Work Funded by Maintenance|Work Funded by Maintenance.]]<br />
<br />
===402.1.2 Mix and Quantities===<br />
Tack quantities are based on tacking the entire roadway surface at an estimated minimum rate of 0.08 gallons/yd<sup>2</sup>. The asphalt binder for the contract leveling course mixture (surface leveling) should typically be PG 64-22. Quantities for asphalt binder and mineral aggregate for individual projects will vary and should be shown, along with the estimate factors used for calculating quantities on the typical section sheets for the project. Minimum thicknesses are 1 in. for Plant Mix Bituminous Surface mixtures, 1 1/4 in. for BP-2 mixtures and 1 3/4 in. for BP-1 mixtures.<br />
<br />
The Bitminous Mixtures Criteria for Contract Leveling Course Projects table below is a guide for selecting bituminous mixtures for contract leveling course projects. If the district elects to use a mixture other than what is specified, the project manager should submit by letter to the Design Division the justification for specifying a different mixture or thickness than given in the table below. In addition, at the bottom of the letter an approval signature block similar to that on the [[media:131.1 Design Exception.docx|Design Exception Information Form]] should be provided for the State Design Engineer.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ '''Bituminous Mixtures Criteria for Contract Leveling Course Projects'''<br />
! style="background:#BEBEBE"|Corridor Designation !! style="background:#BEBEBE"|Traffic !! Style="background:#BEBEBE"|Recommended Mix and Thickness<br />
|-<br />
|text align="center"|Light Duty || text align="center"|AADT < 1750 || text align="center"|1 in. Sec 402 Mixture<sup>'''1'''</sup><br />
|-<br />
|text align="center"|Light Duty || text align="center"|1750 < AADT < 3500 || text align="center"|1 1/4 in. BP-2<sup>'''2'''</sup> (Sec 401)<br />
|-<br />
|colspan="3"|<sup>'''1'''</sup> For structurally sound pavements, 3/4 in. Sec 402 mixture meeting BP-3 requirements may be substituted.<br />
|-<br />
|colspan="3"|<sup>'''2'''</sup> A 1 3/4 in. BP-1 (Sec 401) mixture may be substituted for this application if, in the district's judgment, this substitution is warranted. <br />
|}<br />
<br />
If special situations require limiting loads on a given route, a "Haul Road Restriction" special provision will be considered on a project-by-project basis. Otherwise, the only load restrictions, other than the 80,000-pound legal load limit, will be any posted bridge load limits.<br />
<br />
===402.1.3 Traffic Control, Pavement Marking and Signing===<br />
Traffic control plans and job special provisions should be prepared and submitted by the districts. Traffic control plan templates are available on district servers. Sample job special provisions are also available from the Design Division Review Section. The quantity of "No Center Stripe" Signs should be included as necessary to sign the entire project. On contract leveling jobs, final pavement marking may be required in the contract, included in a district wide pavement marking contract, or done by district forces. The guidance for pavement marking, [[620.1 General (MUTCD Chapter 3A)#620.1.6 Permanent Pavement Markings|General (MUTCD Chapter 3A) - Permanent Pavement Markings]] provide guidance for selection of pavement marking material.<br />
<br />
==402.2 Construction Inspection for Sec 402==<br />
This is not a contract document and is to be used solely as a commentary on Standard Specification Section 402. Surface leveling mixes will be referred to as SL throughout this section. SL mixes are used to correct any irregularities in the surface of an existing pavement on a route with low traffic volumes.<br />
<br />
===402.2.1 Material (Sec 402.2)===<br />
<br />
'''Reclaimed Asphalt Pavement''' (Sec 402.2.3)<br />
<br />
See [[460.3 Plant Inspection#460.3.11 Reclaimed Asphalt Pavement (RAP)|Reclaimed Asphalt Pavement (RAP)]] in Plant Inspection.<br />
<br />
===402.2.2 Composition of Mixture (Sec 402.3)===<br />
<br />
'''Gradation of Combined Aggregates''' (Sec 402.3.1)<br />
<br />
The aggregate sources used in the mix must be the same as those required by the JMF. The combined aggregate shall meet the gradation required in [http://www.modot.state.mo.us/business/standards_and_specs/Sec0402.pdf Standard Specification Section 402.3.1]. <br />
<br />
'''Alternate Gradation''' (Sec 402.3.2)<br />
<br />
If wet bottom boiler slag is used to replace coarse aggregate, the combined aggregate shall meet the gradation required in Standard Specification Section 402.3.2.<br />
<br />
'''Reclaimed Asphalt Pavement''' (Sec 402.3.3)<br />
<br />
See [[460.3 Plant Inspection#460.3.11 Reclaimed Asphalt Pavement (RAP)|Reclaimed Asphalt Pavement (RAP)]] in Plant Inspection.<br />
<br />
===402.2.3 Job Mix Formula (Sec 402.4)===<br />
<br />
The requirements of [http://www.modot.state.mo.us/business/standards_and_specs/Sec0401.pdf Standard Specification Section 401.4] apply.<br />
<br />
===402.2.4 Gradation Control (Sec 402.5)===<br />
<br />
The inspector should perform a sieve analysis on the hot bins or the combined cold feed at a minimum of once per day. Testing may be waived, with the RE’s approval and the contractor’s certification of the mix, when less than 200 tons are produced per day. The combined aggregate gradation must be within the master range specified in [http://www.modot.state.mo.us/business/standards_and_specs/Sec0402.pdf Standard Specification Section 402.3.1] at all times. The combined aggregate gradation can vary from the JMF by the maximum tolerance shown in the table below. The mix shall be produced at the binder content shown on the JMF. However, the binder content of the mix, as determined by calculations or sampling and testing, must be within the following maximum tolerance from the JMF.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|-<br />
!style="background:#BEBEBE"|Property||style="background:#BEBEBE"|Tolerance<br />
|-<br />
| #200 || &plusmn;2.0% <br />
|-<br />
| Binder Content || &plusmn;0.5%<br />
|}<br />
<br />
The Standard Specifications do not put testing requirements on the binder content. However, if there is any reason to suspect that the binder content of the mix is not within these specifications, the inspector should take a sample and determine the binder content of the mix. For example, a sample should be taken and tested if the mix appears too dry or too wet. The binder content, as shown on the JMF, cannot be changed during production without written approval from Construction and Materials, even if the resulting binder content is within the tolerance from the JMF. If a new binder content is approved, the tolerance will apply to the new target. If a sieve analysis indicates a deviation from the JMF exceeding the specified tolerances, the contractor will be notified immediately. The contractor shall then review the cold feed settings and make any necessary adjustments. As soon as any adjustments are completed, another test will be performed. If excessive deviation still exists, the contractor will be informed and production shall stop. Further adjustments or revisions shall be made until an acceptable sieve analysis is obtained. At this time, production can resume. Adjustments in the cold feed percentages in excess of 5.0% may require a new JMF.<br />
<br />
===402.2.5 Sample Location (Sec 402.6)===<br />
See "Reclaimed Asphalt Pavement (RAP)" and "Sieve Analysis" in [[460.3 Plant Inspection|Plant Inspection]]. When sampling for the binder content of the mix, see also "Asphalt Binder Content."<br />
<br />
===402.2.6 Moisture Content (Sec 402.7)===<br />
See [[460.3 Plant Inspection#460.3.14 Asphalt Binder Content|Asphalt Binder Content]]. When sampling for the binder content, also determine the moisture content of the mix. <br />
<br />
===402.2.7 Contamination (Sec 402.8===<br />
See [[460.6 Paving Operations#460.6.6 Material Acceptance|Material Acceptance]].<br />
<br />
===402.2.8 Field Laboratory (Sec 402.9)===<br />
See [[460.3 Plant Inspection#460.3.7 Field Laboratory|Field Laboratory]].<br />
<br />
===402.2.9 Construction Requirements (Sec 402.10)===<br />
<br />
'''Weather Limitations''' (Sec 402.10.1)<br />
<br />
See [[460.6 Paving Operations#460.6.3 Weather Conditions|Weather Conditions]]. SL mixes shall not be placed if the ambient air temperature or the existing surface temperature is below 50°F. <br />
<br />
'''Bituminous Mixing Plants''' (Sec 402.10.2)<br />
<br />
See [[:Category:404 Bituminous Mixing Plants|Bituminous Mixing Plants]]. <br />
<br />
'''Subgrade Preparation''' (Sec 402.10.3)<br />
In this case, subgrade refers to the existing pavement. Before the project begins, District Maintenance should perform any necessary repairs that may not be compensated for by the surface leveling. Deep rutting or dips should be filled prior to the placement of the surface leveling unless otherwise directed by the District Construction and Materials Engineer. The existing pavement surface should be cleaned and tacked in accordance with Standard Specification Section 407. <br />
<br />
'''Hauling Equipment''' (Sec 402.10.4)<br />
<br />
See [[460.4 Paving Equipment#460.4.2 Haul Trucks|Haul Trucks]].<br />
<br />
'''Spreading''' (Sec 402.10.5)<br />
<br />
See [[460.6 Paving Operations#460.6.4 Spreading|Spreading]] and [[460.6 Paving Operations#460.6.5 Hand Spreading|Hand Spreading]] in Paving Operations. <br />
<br />
:'''Irregularities''' (Sec 402.10.5.1)<br />
<br />
See [[460.6 Paving Operations#460.6.4 Spreading|Spreading]] in Paving Operations.<br />
<br />
'''Joints''' (Sec 402.10.6)<br />
<br />
See [[460.6 Paving Operations#460.6.8 Transverse Joints|Transverse Joints and Longitudinal Joints in Paving Operations]].<br />
<br />
'''Compaction''' (Sec 402.10.7)<br />
<br />
See [[460.4 Paving Equipment#460.4.5 Rollers|Rollers in Paving Equipment]] and [[460.6 Paving Operations#460.6.7 Compaction|Compaction]] in Paving Equipment. At least 3 passes shall be made over the entire mat with either a pneumatic tire roller or a steel wheel roller. The steel wheel roller may be a static or vibratory roller. SL mixes are generally placed very thin (minimum of 1 in.). Therefore, the reaction of the mat to compaction must be watched very closely. The inspector should ensure that the roller(s) used for compaction weigh at least 10 tons. A steel wheel roller, or a vibratory roller operated in static mode, must be used for final rolling.<br />
<br />
'''Surface Condition''' (Sec 402.10.8)<br />
<br />
See [[460.6 Paving Operations#460.6.6 Material Acceptance|Material Acceptance]].<br />
<br />
===402.2.10 Method of Measurement=== <br />
<br />
The total tonnage accepted will be measured to the nearest 0.1 ton. <br />
<br />
===402.2.11 Basis of Payment===<br />
<br />
The accepted quantity of SL mix will be paid for at the contract unit price. The contract unit price is set up as total mix (mineral aggregate and asphalt binder are no longer paid for separately).<br />
<br />
==402.3 Materials Inspection for Sec 402==<br />
<br />
===402.3.1 Scope===<br />
To establish procedures for mix design of plant mix bituminous surface leveling. Ingredients for use in plant mix bituminous surface leveling are to be inspected in accordance with the applicable guidelines. Trial mix aggregate samples shall be submitted in accordance with [[:Category:1001 General Requirements for Material|EPG 1001 General Requirements for Material]]. Plant calibrations, if requested, shall be performed in accordance with [[106.4 Plant Inspections|EPG 106.4 Plant Inspections]].<br />
<br />
===402.3.2 Procedure===<br />
Mix design procedures are identical to those shown in [[:Category:403 Asphaltic Concrete Pavement#403.2 Materials Inspection|Materials Inspection]] in Asphaltic Concrete Pavement. If it becomes necessary to calculate a mix, the formulae, procedure and reporting shall be performed as described in [[:Category:403 Asphaltic Concrete Pavement#403.3 Laboratory Procedures for Sec 403|EPG 403.3 Laboratory Procedures for Sec 403]].<br />
<br />
==402.4 Laboratory Procedures for Sec 402==<br />
This establishes procedures for Laboratory testing and reporting of plant mix bituminous surface leveling trial mixtures.<br />
<br />
===402.4.1 Procedure===<br />
Trial mixture test results and calculations required for plant mix bituminous surface leveling will be determined as shown in [[:Category:403 Asphaltic Concrete Pavement#Laboratory Procedures for Sec 403|Laboratory Procedures for Sec 403]]. No field compacted density samples are required.<br />
<br />
===402.4.2 Sample Record===<br />
The sample record shall be completed in SiteManager, as described in [[:Category:101 Standard Forms#Sample Record General Information| Sample Record General Information]] [[image:bulldozer.jpg|20px]]. Test results shall be reported on the appropriate templates under the Tests tab.<br />
<br />
==402.5 Maintenance Operations Following Contract Level Course Projects==<br />
Once the contractor completes a surface leveling project (1” contract overlay), there are several tasks left for MoDOT to complete before the job is finished. (Note: this guidance may apply to other overlay projects as well, depending on the requirements of the contract). To ensure these tasks are completed, the Resident Engineer must coordinate the activities with local maintenance staff. This should start by inviting the maintenance superintendent to the pre-construction conference and continue by keeping maintenance staff up to date with the contractor’s schedule.<br />
<br />
Work items to be completed by MoDOT:<br />
<br />
:'''1. Eliminate Pavement Edge Drop-offs.''' Maintenance crews will need to eliminate edge drop-offs by adding edge rock, or by pulling up existing material with a motor grader or shoulder disc.<br />
<br />
:'''2. Bring Entrances up to Grade.''' Additional rock may be needed to bring aggregate entrances up to grade, or there may be sufficient rock on the entrance that can be pulled up.<br />
<br />
:'''3. Pavement Marking.''' Unless otherwise indicated in the contract, permanent pavement marking will be included in the contract. If MoDOT striping crews will place the final pavement markings, the contractor shall install [[620.1 General (MUTCD Chapter 3A)#Temporary Raised Pavement Markers|Temporary Raised Pavement Markers]] (TRPMs) and [http://epg.modot.org/index.php?title=616.6_Temporary_Traffic_Control_Zone_Devices_%28MUTCD_6F%29#616.6.47_NO_CENTER_LINE_Sign_.28WO8-12.29_.28MUTCD_6F.47.29 NO CENTER LINE] signs. Additionally, the contractor will remove and retain the NO CENTER LINE signs after the markings are complete. MoDOT will remove the TRPMs after the MoDOT placed pavement marking is complete.<br />
<br />
:'''4. Removal of Temporary Raised Pavement Markers (TRPM).''' Per specification, the contractor is only responsible for removing TRPMs when they are also responsible for providing the final pavement marking. When MoDOT provides the pavement marking, MoDOT is responsible for removing the TRPMs. The TRPMs should be removed following placement of the pavement marking. Leaving the TRPMs in place until snowplowing operations is not an acceptable option since it may result in property damage claims, creating holes in the pavement and littering the roadsides and streams with the markers. There are many creative ways to safely remove the TRPMs mechanically, including the Tab Remover, which was a regional winner in the Innovations Challenge.</div>Jonesjbhttps://epg.modot.org/index.php?title=File:402_JSP_FY15.doc&diff=34045File:402 JSP FY15.doc2014-07-11T18:02:19Z<p>Jonesjb: </p>
<hr />
<div></div>Jonesjbhttps://epg.modot.org/index.php?title=806.8_Storm_Water_Pollution_Prevention_Plan_(SWPPP)&diff=34029806.8 Storm Water Pollution Prevention Plan (SWPPP)2014-07-09T19:45:51Z<p>Jonesjb: minor clarifications</p>
<hr />
<div>==806.8.1 Introduction to the Storm Water Permit and Storm Water Polution Prevention Plan (SWPPP)==<br />
<br />
{|style="padding: 0.3em; margin-right:1px;margin-left:5px; border:3px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="390px" align="right" <br />
|-<br />
|<center>'''[[media:806.8 SWPPP 2014.pdf|Easily Printable Version of SWPPP]]'''</center><br />
|-<br />
|EPG 806.8 SWPPP presents the very latest SWPPP information, but this pdf file may be helpful for those wanting to easily print the SWPPP information. <br />
|-<br />
|Also available is the '''[[media:806.8 SWPPP revisions.pdf|2014 SWPPP in revision mode]]''' so that the reader can view the changes made to the 2012 version of the SWPPP.<br />
|-<br />
|<center>'''<sup>______________________</sup>'''</center><br />
|-<br />
|<center>'''Forms and Figures'''</center><br />
|-<br />
|[[media:Fig. 806.8.1 2014.docx|Fig. 806.8.1 MoDOT/Contractor Responsibility]]<br />
|-<br />
|[[media:Form 806.8.2 black.docx|Form 806.8.2, Project-Specific SWPPP Information]]<br />
|-<br />
|[[media:Fig. 806.8.2.pdf|Example of completed Form 806.8.2]]<br />
|-<br />
|[[media:Fig. 806.8.9 2014.docx|Fig. 806.8.9 Example Erosion/Sediment Control Site Plans]]<br />
|-<br />
|[http://ghepg01/forms/CO/Land%20Disturbance%20Inspection%20Record%20-%20Electronic%20Version.dotx Form 806.8.10 MoDOT Land Disturbance Inspection Record]<br />
|-<br />
|[[media:Fig. 806.8.14.docx|Fig. 806.8.14 Example MDNR SWPPP Evaluation Form]] <br />
|-<br />
|[[media:Fig. 806.8.15.docx|Fig. 806.8.15 Imhoff Cone and Turbidity Tube Testing Procedures]]<br />
|-<br />
|<center>'''<sup>______________________</sup>'''</center><br />
|-<br />
|<center>'''Additional Information'''</center><br />
|-<br />
|<center>[http://wwwi/intranet/cm/documents/LandDisturbanceTraining2012.pdf '''Land Disturbance Workshop 2012'''</center>]<br />
|-<br />
|<center>[[media:806.8 Land Disturbance 2013.ppt|'''Land Disturbance Training 2013''']], a summarized refresher presentation</center><br />
|}<br />
<br />
[[image:806.8.jpg|right|320px]]<br />
Provisions of the federal Clean Water Act and related state rules and regulations require stormwater permits where construction activities disturb greater than one acre over the life of a project as part of a common plan or sale. MoDOT has a general [http://www.dnr.mo.gov/env/wpp/permits/issued/R100000.pdf State Operating Permit], obtained from the [http://www.dnr.mo.gov/ Missouri Department of Natural Resources (DNR)], that allows for land disturbance activities associated with highway, bridge and compensatory mitigation construction as well as maintenance activities related to the upkeep of these features. The permit stipulates that MoDOT will follow certain erosion and sediment control guidelines and install temporary and permanent erosion and sediment control measures. Locally sponsored federal aid projects that are performed on MoDOT right of way and are using MoDOT’s land disturbance permit are required to comply with MoDOT Standard Specifications, and therefore, must follow this Stormwater Pollution Prevention Plan (SWPPP). When working adjacent to MoDOT right of way, cities, counties and other government entities may already possess their own State Operating Permit and, in that case, must comply with their own SWPPP.<br />
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There are instances where contractors may have to obtain their own permits for work involving borrow and excess (waste) disposal areas, and in some instances when portable plants are used. (See [[media:Fig. 806.8.1 2014.docx|Fig. 806.8.1 MoDOT/Contractor Responsibility]] for details about the permitting requirements of these scenarios.) Also, in a few rare cases, MoDOT may require contractors to obtain their own individual State Operating Permit for land disturbance activities even though the project is being constructed on MoDOT right of way. These unique situations will normally be [[:Category:139 Design - Build|design/build projects]] that are funded by MoDOT, but totally managed by the contractor. <br />
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<div id="The purpose of the SWPPP is to ensure"></div><br />
The purpose of the SWPPP is to ensure the design, implementation, management and maintenance of [[:Category:806 Pollution, Erosion and Sediment Control#806.7.3 Best Management Practices (BMP) |Best Management Practices (BMPs)]] in order to reduce the amount of sediment and other pollutants in storm water discharges associated with the land disturbance activities; comply with the [http://www.dnr.mo.gov/env/wpp/wqstandards/wq_criteria.htm Missouri Water Quality Standards], and ensure compliance with the terms and conditions of the general permit.<br />
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The following documents were used in the preparation of this SWPPP:<br />
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:*'''Best Management Practices for Erosion and Sediment Control''', (Report No. FHWA-FLP-94-005) published by the United States Department of Transportation (1995)<br />
:*'''Storm Water Management for Construction Activities: Developing Pollution Prevention Plans and Best Management Practices''', (Document number EPA 832-R-92-005) published by the United States Environmental Protection Agency (1992)<br />
:*'''Protecting Water Quality: A field guide to erosion, sediment and storm water best management practices for development sites in Missouri'''<br />
:*'''[http://www.modot.mo.gov/business/standards_and_specs/highwayspecs.htm Missouri Standard Specifications for Highway Construction]'''<br />
:*'''Missouri Department of Transportation Engineering Policy Guide<br />
:*[http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm?action=min_measure&min_measure_id=4 '''Menu of BMPs – United States Environmental Protection Agency'''].<br />
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A typical MoDOT project involves the implementation of many documents, processes and standard operating procedures. These various processes and procedures are of such detail that it is impossible to include in this brief summary of BMPs. Pollution from storm water can be reduced by the implementation of the BMPs, construction techniques and site management measures in this article. However, pollution from storm water will also be reduced by the issuance of change orders, letters/memos of notification, Order Records and Contractor Performance Reports. Changes that occur as a result of directives to contractors will usually be documented by Document Records and other various product and reports produced by the computer program, [http://wwwi/intranet/cm/siteManager.htm SiteManager]. Lastly, a Semi-Final Inspection Report can serve to identify post-construction measures that will ensure permit compliance and water quality protection. <br />
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In addition to these contract management tools, MoDOT conducts annual storm water permit compliance training for construction site inspectors, resident engineers, desingners and other personnel including contractors and consultants. The information distributed in that class goes beyond the scope of this statewide SWPPP document. Many effective BMPs and construction techniques are discussed during that training, but may not yet appear in this article.<br />
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These and other unique MoDOT tools must be considered elements of a SWPPP because they all result in implementation of measures that cause or caused a resultant action to occur on a construction project.<br />
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==806.8.2 Site Description and Project-Specific Information==<br />
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[[237.1 Plan Details|EPG 237.1 Plan Details]] describes the information that is to be included in all plans that are used by contractors to construct MoDOT projects. All highway and bridge projects are constructed from a set of design plans that are generated by MoDOT designers or consultants. The plans show all existing topographic features, buildings, roadways and drainages, as well as right of way limits. Within a project’s design plans are erosion and sediment control plans which serve as the site maps for the project to be used in combination with this narrative SWPPP. These plans contain sufficient information to be of practical use to contractors and site construction workers to guide the installation of BMPs in the interim and final stages of construction. Site plans are on location at active MoDOT job sites when MoDOT’s construction inspector or the contractor superintendent is on site. These plans will usually include hand written notes showing the locations of temporary and in some cases, permanent BMPs. <br />
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Contract plans shall include erosion and sediment control measures that are sufficient to protect streams, lakes, wetlands and private land adjacent to MoDOT right of way, and the location of most of these controls will be depicted on the plan sheets. The exact location of the controls that are shown on plan sheets will be determined in the field by the engineer or inspector. Temporary control measures shall be coordinated with permanent control measures to assure economical, effective and continuous erosion and sediment control. Construction of permanent erosion control measures that may contribute to the control of siltation, shall be accomplished at the earliest practicable time.<br />
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MoDOT site maps (erosion and sediment control plans) are to include:<br />
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:* Direction(s) of stormwater flow and approximate slopes anticipated after grading activities<br />
:* Areas of soil disturbance and areas that will not be disturbed<br />
:* Location of major structural and non-structural BMPs<br />
:* Locations where stabilization practices are expected to occur<br />
:* Locations of on and/or off-site material, waste, borrow or equipment storage areas<br />
:* Locations of all waters of the U.S.<br />
:* Locations where stormwater discharges to a surface water<br />
:* Areas where final stabilization has been accomplished and no further construction-phase permit requirements apply.<br />
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Every MoDOT project with one or more acres of total land disturbance must complete [[media:Form 806.8.2 black.docx|Form 806.8.2, Project-Specific SWPPP Information]] and retain it as part of the SWPPP. The project office will be responsible for completing this form for all jobs with one or more acres of total land disturbance. See [[media:Fig. 806.8.2.pdf|Fig. 806.8.2]] for an example of how to complete this form.<br />
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==806.8.3 Drainage Areas and Housekeeping==<br />
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In compliance with the Missouri Clean Water Law ([http://moga.mo.gov/statutes/C600-699/6440000051.HTM Section 644.051]), neither MoDOT nor MoDOT's contractors shall pollute any waters of the state, or place, cause, or permit to be placed any water contaminant in a location where it is reasonably certain to cause pollution of any waters of the state. To comply with this law, proper preventive measures and good housekeeping shall be maintained on job sites. Job site litter, construction debris and sanitary waste should be controlled. All litter shall be placed in appropriate containment receptacles. The use of portable toilets may be necessary to control sanitary waste in some situations. If used, these facilities shall be adequately placed and maintained so as not to cause a safety or environmental concern. If hazardous waste is generated or encountered on a job site, the MoDOT Environmental Section, (573) 526-4778, should be informed immediately to assure proper handling and compliance with environmental regulations. Also, neither MoDOT nor MoDOT's contractors shall discharge water contaminants into any waters of the state, which reduce the quality of these waters below the state's water quality standards. These water quality standards include the following ([http://sos.mo.gov/adrules/csr/current/10csr/10c20-7a.pdf MO 10 CSR 20-7]):<br />
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:'''(a)''' Waters shall be free from substances in sufficient amounts to cause the formation of putrescent, unsightly or harmful bottom deposits or prevent full maintenance of beneficial uses.<br />
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:'''(b)''' Waters shall be free from oil, scum and floating debris in sufficient amounts to be unsightly or prevent full maintenance of beneficial uses.<br />
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:'''(c)''' Waters shall be free from substances in sufficient amounts to cause unsightly color or turbidity, offensive odor or prevent full maintenance of beneficial uses.<br />
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:'''(d)''' Waters shall be free from substances or conditions in sufficient amounts to result in toxicity to human, animal or aquatic life.<br />
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:'''(e)''' Waters shall be free from physical, chemical or hydrologic changes that would impair the natural biological community.<br />
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:'''(f)''' Waters shall be free from used tires, car bodies, appliances, demolition debris, used vehicles or equipment and solid waste as defined in Missouri’s Solid Waste Law, [http://moga.mo.gov/STATUTES/C260.HTM Section 260.200, RSMo], except as the use of such materials is specifically permitted pursuant to Section 260.200–260.247.<br />
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MoDOT personnel or contractors hired by MoDOT shall comply with these and any other federal, state, and local laws and regulations controlling pollution of the environment. To ensure that these general criteria are met, the following guidelines will be observed:<br />
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:'''1)''' Machinery shall be kept out of the waterway as much as possible.<br />
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:'''2)''' Fuel, lubricants, debris and other water contaminants shall not be stored in areas that are subject to contact with water (such as adjacent to stream banks) or where contaminated runoff from the storage areas can enter waters.<br />
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:'''3)''' Refueling and maintenance (e.g., oil changing) of machinery shall not take place in, or directly alongside, any water body.<br />
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:'''4)''' Clearing of vegetation/trees shall be kept to the minimum required to accomplish the activity.<br />
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:'''5)''' Riparian areas and banks shall be restored to a stable condition through recontouring and revegetation of the area, as necessary, as soon as possible (normally within three working days of final contouring).<br />
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:'''6)''' Work shall be conducted during low flow whenever possible.<br />
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:'''7)''' Wetland areas shall be avoided to the extent practical.<br />
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:'''8)''' Work shall conform to all conditions that are part of the USACOE Section 404 permit and the ancillary MDNR Section 401 Water Quality Certification. <br />
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[[127.19 Section 404 Clean Water Act for Bridge Demolitions|EPG 127.19 Section 404 Clean Water Act for Bridge Demolitions]] provides a detailed explanation of the process that is followed whenever a stream or drainage channel may fall into USACOE jurisdiction.<br />
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==806.8.4 Erosion and Sediment Control [http://www.modot.mo.gov/business/standards_and_specs/DIV0800.pdf (MO Specifications Division 800)]==<br />
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Water pollution control measures shall be required of all contractors MoDOT hires. The contractor shall exercise best management practices throughout the project to control water pollution. Construction of permanent drainage facilities and other activities, which may contribute to the control of siltation, shall be accomplished at the earliest practicable time. This work shall consist of furnishing, installing, maintaining, and removing temporary control measures as shown on the plans (see MoDOT [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf Standard Plan 806.10]) or as ordered by the [[:category:105 Control of Work#105.9 Authority and Duties of Resident Engineer (Sec 105.9)|engineer]]. The control of water pollution will be accomplished through the use of berms, slope drains, ditch checks, sediment basins, seeding and mulching, straw bales, silt fences and other erosion and sediment control devices or methods. Pollutants such as chemicals, fuels, lubricants, bitumens, raw sewage or other harmful materials shall not be discharged from the project. No work shall be started until the erosion and sediment control timetable and methods of operation have been approved.<br />
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Temporary erosion control measures shall be coordinated with permanent erosion control measures to assure economical, effective and continuous erosion and sediment control. Temporary erosion controls must be kept in place and maintained until revegetation, rock blanketing, paving, or another form of stabilization has occurred to an extent sufficient to to minimize sediment loss from the project and comply with MoDOT’s State Operating Permit. <br />
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Materials required for erosion and sediment control measures shall meet the standards of the ''Missouri Standard Specifications for Highway Construction''. <br />
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===806.8.4.1 Construction Requirements===<br />
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The [[:category:105 Control of Work#105.9 Authority and Duties of Resident Engineer (Sec 105.9)|engineer]] may limit the surface area of erodible earth material exposed by clearing and grubbing, or excavation, [[:Category:135 The Section 106 Process#135.3 Borrow and Excess Material Areas|borrow]], and fill operations, and may direct the contractor to provide immediate permanent or temporary erosion and sediment control measures to prevent contamination of adjacent streams or other watercourses, wetlands, lakes, ponds, and other water impoundments. Such work may involve the construction of temporary berms, dikes, dams, sediment basins, slope drains, and the use of temporary seeding and mulching, or other erosion and sediment control devices or methods as necessary.<br />
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The contractor shall be required to incorporate all permanent erosion control measures into the project at the earliest practicable time. [[:Category:806 Pollution, Erosion and Sediment Control|Temporary erosion and sediment control measures]] shall be used to correct conditions that develop during construction which were not foreseen during the design stage. Temporary erosion control shall also be used when needed prior to installation of permanent erosion control measures or to control erosion that develops during normal construction practices, but are not associated with permanent control measures on the project.<br />
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When practical, clearing and grubbing operations shall be scheduled and performed so that border, perimeter, or outlet BMPs to control runoff from disturbed areas will be installed or marked for preservation before general site clearing. A limited amount of clearing (enough to gain access to the area) may be permissible to enable the installation of outlet and perimeter controls. Stormwater discharges from disturbed areas, which leave the site, shall pass through an appropriate impediment (BMP) prior to leaving the site. The surface area of erodible earth material exposed at one time by clearing and grubbing, by excavating, by fill, or by borrow, shall be minimized to limit runoff. The engineer may limit the total acreage of erodible earth material to be exposed at one time as determined by an analysis of project conditions. In such cases the engineer will identify specific BMPs and controls that have been, or will be installed in order to exceed the specified maximum disturbed acreage threshold.<br />
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The engineer will limit the area of [[:Category:201 Clearing and Grubbing|clearing and grubbing]], excavation, borrow and embankment operations in progress commensurate with the contractor's ability to keep the finish grading, mulching, seeding and other erosion control measures current. Should seasonal limitations make such coordination unrealistic, temporary erosion control measures shall be implemented as directed by the engineer.<br />
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Unless otherwise approved, construction operations in rivers, streams, wetlands and impoundments shall be restricted to those areas that must be entered for the construction of temporary or permanent structures. Rivers, streams, wetlands and impoundments shall be promptly cleared of all falsework, piling, debris or other obstructions placed therein or caused by the construction operations.<br />
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Frequent fording of live streams or wetlands with construction equipment is not permitted. Temporary bridges or other structures shall be used wherever an appreciable number of stream crossings are necessary. All temporary fills and structures placed in streams, wetlands, or impoundments will be removed and the site returned to natural or intended contours prior to completion of construction. Unless otherwise approved, mechanized equipment shall not be operated in live streams except as may be required to construct channel changes and temporary or permanent structures. If a Section 404 permit is applicable for a project, its requirements and/or conditions shall be followed.<br />
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Site-specific erosion and sediment controls above and beyond MoDOT standard specifications shall be discussed with the contractor at a preconstruction conference. Special conditions may be developed which can include limitations on the amount of surface area that can remain unprotected at one time or special water quality or stream protections requirements.<br />
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The location of all local material pits (other than commercially operated sources) and all excess material areas shall be subject to the approval of the engineer (''material in this case refers to soil and rock''). Construction operations shall be conducted and pollution control measures implemented so that erosion will not result in water pollution.<br />
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Portable concrete and asphalt plants located on MoDOT right of way can be covered under the "[[media:127.25.4.1 permit.pdf|MoDOT State Operating Permit]]''. Any discharges from these operations must be managed by appropriate BMPs. The plant and BMPs must be depicted on the project site map and appropriately accounted for in the project SWPPP. Operators of portable plants that are located off of MoDOT right of way will be responsible for obtaining all appropriate permits directly from the DNR. The contractor is responsible for all costs associated with erosion and sediment control to protect plant locations, regardless if the plant is located on or off of MoDOT right of way or easements. <br />
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Borrow and excess (waste) disposal sites located on MoDOT right of way or owned by MoDOT can be covered by the MoDOT permit and SWPPP. For borrow and excess disposal activities not located on MoDOT right of way, the borrow or excess disposal operator will be responsible for obtaining all appropriate permits, including a land disturbance permit directly from the DNR for sites greater than or equal to one acre. <br />
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In the event of a conflict between these requirements and pollution control laws, rules, or regulations of other federal, state, or local agencies, the more restrictive laws, rules, or regulations may apply.<br />
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===806.8.4.2 Non-Structural Control Measures===<br />
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Protection of existing vegetation is an important and too-often overlooked component of erosion and sediment control. Prior to commencement of grading, design plans will show areas that are to remain undisturbed. Maintaining natural vegetation in certain areas during construction serves to reduce sediment from sheet flow, and slow the flow of water that travels through the area. These areas of excess right-of-way provide the same benefit to water quality as would many types of structural controls such as silt fences, sediment basins or sediment traps. Deposited material may or may not be removed from the area of excess right of way depending on MoDOT's future plans for the area.<br />
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Vegetated filter strips along the shoulder, or within the median of MoDOT highways serve as excellent sediment capture devices particularly in areas where the density of grass and other herbaceous vegetation can filter the water. In most cases vegetative filter strips (permanent vegetative cover) are used in concert with other BMPs (such as silt fence). However, there may be situations where vegetative filter strips can suffice as standalone features. If vegetated filter strips are used, they must be located within MoDOT right of way or easement. Vegetation on an adjacent property cannot be used as a MoDOT BMP. <br />
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Other Non-Structural BMPs such as seeding, mulching, stabilized construction entrances, flocculants and other chemical additives are discussed elsewhere in this document. <br />
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<div id="Erosion Control Measures"></div><br />
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===806.8.4.3 Erosion Control Measures (MO Specifications - Special Provisions)===<br />
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Our emphasis on MoDOT projects should be erosion control and focusing on covering up exposed soil, preferably with permanent vegetation, rock, pavement, etc., as soon as practical in order to protect the soil surface and keep soil particles from dislodging and entering stormwater. Best management practices (BMPs) shall be used by contractors to minimize sediment loss from MoDOT right of way onto adjacent land or into streams, lakes, ponds, wetlands, drainage channels, etc..<br />
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The following described practices are commonly used erosion control BMPs that may be used individually or in combination with other practices, such as the sediment control devices discussed in [[#806.8.4.4 Sediment Control Measures|EPG 806.8.4.4 Sediment Control Measures]], to assure effective erosion control and prevent off site delivery of pollutants. Other practices that are not listed here, or have not been identified or invented at the time of the preparation of this SWPPP, may be used if their performance is equivalent or better than the practices listed below.<br />
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====806.8.4.3.1 Soil Surface Roughening====<br />
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Surface roughening is a temporary erosion control BMP that will reduce runoff velocity and erosion potential by increasing infiltration and sediment trapping. This practice is intended for areas which have been cleared and grubbed and are awaiting application of temporary or permanent seed, or installation of other structural controls such as ditch checks, sediment traps, or sediment basins. The practice is NOT intended to serve as a stand-alone best management practice and is only to be used as a short-term, sequential practice as the grading and seeding proceeds.<br />
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Where backslopes are unlikely to be mowed or maintained due to steepness and lack of access, surface roughening can be a permanent measure. In these situations seed and mulch may be applied directly to the roughened seed bed. This will aid in the establishment of vegetative cover and will minimize destructive compaction by heavy equipment. There are three common methods of surface roughening (tracking, grooving, stair stepping) that can be employed depending on the soil type, slope and potential maintenance concerns for the project.<br />
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:'''A. Tracking''' involves the use of tracked construction equipment (dozer, high lift, etc.) vertically tracking up and down slopes in order to create horizontal depressions, perpendicular to the runoff path, on the soil surface. These depressions reduce stormwater velocity and the potential for concentrated runoff, which typically leads to rill formation. Tracking can lead to significant soil compaction, which does help lock soil particles in place; however, it is also undesirable for root production and grass growth. Due to this fact, care should be taken in deciding which slopes to track. Tracking is typically recommended for sandy soils, where risk of excessive compaction is reduced.<br />
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:'''B. Grooving''' involves the creation of a series of ridges and depressions that run along the contour of a slope. The grooves can be created using a variety of implements such as a disks, harrows, chisel plows, loader teeth, etc. The grooves should be no more than 3 inches deep and no more than 15 in. apart. <br />
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:'''C. Stair-stepping''' involves creating stair steps to reduce runoff velocity and encourage sedimentation on steeper slopes that will not be mowed. The stairs should be cut such that the vertical step does not exceed 1 foot. The horizontal step should be longer than the vertical step and sloped inward toward the vertical step face to promote sedimentation. <br />
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====806.8.4.3.2 Mulching and Crimping====<br />
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Application of mulch without seed may be used as a temporary best management practice if approved by the engineer. This temporary stabilization practice is most applicable in late fall or early winter when grass seed would have little or no opportunity to germinate. Straw mulch should be applied with a mulch blower, or by hand, and must be anchored (crimped or otherwise tackified) immediately after spreading to prevent windblow. Application rates will vary based on the percent slope. Bark mulch and/or wood chips do not require crimping. The engineer will determine whether or not the wood chip mulch may remain in place, be cultivated or be modified for permanent seeding.<br />
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====806.8.4.3.3 Temporary Berms - Erosion Control====<br />
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A temporary berm is a temporary ridge of compacted soil, with or without a shallow ditch, constructed at the top of fill slopes or transverse to centerline on fills. The purpose of these ridges is to divert storm runoff from small areas away from steep slopes and direct this water to temporary outlets where the water can be discharged with minimum slope erosion. These ridges are used temporarily at the top of newly constructed slopes to prevent excessive erosion until permanent controls are installed and/or slopes are stabilized. They are also used transverse to grade to divert runoff to stabilized slope drains. Weekly (and post-rainfall) monitoring will be necessary to identify breeches in all temporary berms used as BMPs. <br />
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'''Type A Berms''' for erosion control may be specified for use at the end of each day’s operations on embankments to divert stormwater away from project slopes and toward stabilized drop down structures/pipes or stormwater detention areas, sediment capture devices, etc. They will be constructed to specified dimensions (see MoDOT [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf Standard Plan 806.10]) and machine compacted with a minimum of one pass over the entire width of the berm with a dozer tread, grader wheel, etc. Type A Berms can be used until grading operations cease and final contours are achieved. Removal will usually occur just before the application of seed and mulch or other soil stabilization measures.<br />
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'''Type B Berms''' are constructed on the top of fill slopes and are intended to direct runoff water into a temporary slope drain. These temporary diversion structures are specified when embankment operations are shut down over extended periods of time (i.e., winter), and will be constructed to specified dimensions (see MoDOT [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf Standard Plan 806.10]). The top width of these berms may be wider and the side slopes flatter on transverse berms to allow equipment to pass over these berms with minimal disruption. Operation and maintenance concerns are limited to ensuring that the majority of runoff water is directed into the inlet of the slope drain. Removal of Type B Berms will normally occur when base rock is installed, prior to paving. <br />
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====806.8.4.3.4 Temporary Pipe Slope Drains ====<br />
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A temporary pipe slope drain (see MoDOT [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf Standard Plan 806.10]) is used to carry water down slopes to reduce erosion and may consist of half-round pipe, metal pipe, plastic pipe, or flexible rubber pipe. Temporary slope drains are usually required on fill slopes at approximately 500-foot intervals or as directed by the engineer. These structures are installed after the fill slope has reached its intended elevation and final grade.<br />
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All temporary slope drains will be adequately anchored to the slope to prevent disruption by the force of the water flowing in these drains. The inlet end will be properly constructed to channel water into the temporary drain. The outlet ends will usually have some means of dissipating the energy of the water to reduce erosion downstream and will have a sediment control BMP or a system of sediment control BMPs to capture sediment carried within the stormwater. Where scour at the outlet is of lesser concern due to the physical characteristics of the ditch, there shall still be sediment capture devices in the ditch or drainage outlet downgrade from the slope drain outlet. Unless otherwise specified, all temporary slope drains will be removed when no longer necessary due to the slopes being stabilized or the routing of runoff down permanent letdown structures. Upon removal of temporary slope drains, the site will be restored to match the surroundings.<br />
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====806.8.4.3.5 Interception Ditches and Letdown Structures (Including Roadside & Median Ditches)====<br />
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Interception ditches and letdown structures are typically permanent erosion control BMPs that capture stormwater run-on or runoff and transport it down slopes through stabilized channels. These channels are typically constructed in a “V”, “U”, or trapezoidal shape to concentrate water flow down the center of the structure in order to minimize the risk of break over points and flanking. They are typically lined with stone (riprap), erosion control blankets, turf reinforcement mats, or other product which is self-adjusting and capable of withstanding concentrated, erosive flows. In some instances, these ditches and letdowns may be constructed as concrete or asphalt gutters; however, these types of rigid channel liners do not allow for water infiltration and more often than not, do not have built-in energy dissipation, which can exacerbate erosion at their outlets. In addition, due to their rigid nature, concrete and asphalt-lined drainage courses often undermine and experience section loss, which leads to system failure. There are alternative BMP technologies available (ScourStopTM, FlexamatTM, etc.) that give a degree of rigidity, if desired, to help armor the channel, or a portion of the channel more susceptible to erosion, while still allowing permeability for vegetative growth and water infiltration, as well as self-adjustment to prevent system failure.<br />
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When designing and implementing interception ditches and letdowns, as well as roadside and median ditches, it is important to take into consideration drainage area, soil type, slope and ditch shape in order to determine if the shear stresses within the ditch will be of a high enough value to warrant a liner beyond just vegetative cover. Depending on the location of the ditch, driver safety must also be taken into consideration when choosing an appropriate ditch liner.<br />
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====806.8.4.3.6 Temporary Pipes and Temporary Construction Crossings====<br />
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A temporary pipe is a conduit used temporarily to carry water under a haul road, silt fence, etc. Temporary pipes should be installed in the same manner as permanent pipe is installed on the project to assure that the water does not cause erosion around the pipe. If applicable, material to backfill the pipe should be placed in six-inch lifts and mechanically compacted, although a compaction test is not required. As additional erosion protection, temporary pipes can also be used to collect site run-on and covey it across disturbed areas on the job. Care should be taken to ensure the outlet of the temporary pipe is stabilized and adequate energy dissipation is available so as to not cause erosion of the receiving area.<br />
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Temporary pipes can also be used to convey normal and expected high flows at temporary stream crossings, preventing the contractor's equipment from coming into direct contact with the water when crossing active streams as discussed in [[#806.8.4.1 Construction Requirements|EPG 806.8.4.1 Construction Requirements]]. Any temporary structures used to facilitate construction (e.g. temporary crossings, temporary work pads) will be constructed of clean rock fill that is of sufficient size to be non-erodible under normal stream flow and also easily recoverable upon project completion. Temporary stream crossings will be sufficiently piped to allow for continuous and relatively unimpounded stream flow. The pipes will be placed to match the existing stream grade, which will allow for unimpeded aquatic life passage through the project area. Upon project completion, any temporary structure(s), including pipes and other materials, shall be completely removed and the area will be restored and stabilized. (Note: Temporary stream crossings can act as conduits for sediment to make its way to streams, because they usually cause a gap in perimeter BMPs along streambanks. If possible, stormwater runoff should be diverted away from these structures; otherwise other BMPs must be employed to adequately protect the waterbody.) <br />
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====806.8.4.3.7 Energy Dissipaters==== <br />
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An energy dissipater is a physical structure that is intended to reduce the erosive energy that is typically encountered down grade from a pipe or culvert. As such, these BMPs are normally permanent. Erosive energy from intense flows may also be encountered in median ditches or road ditches. Energy dissipation may be accomplished by the installation of large boulders, wood pilings, engineered concrete structures or other means approved by the engineer, following construction of the ultimate drainage channel or device. Unlike ditch checks and sediment traps, energy dissipaters are NOT intended to impound water and sediment. Energy dissipaters must be constructed in a fashion such that the water that flows through, over or around the structure is equally distributed in the discharge channel and does not exacerbate or cause a resultant erosion problem. <br />
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====806.8.4.3.8 Seeding and Mulching====<br />
=====806.8.4.3.8.1 Temporary Seeding and Mulching (MO Specifications [http://www.modot.mo.gov/business/standards_and_specs/Sec0802.pdf Sec 802] and [http://www.modot.mo.gov/business/standards_and_specs/Sec0805.pdf Sec 805])=====<br />
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This work shall consist of preparing and fertilizing a seedbed, furnishing and sowing of seed, and mulching. The purpose of temporary seeding and mulching is to produce a quick ground cover to reduce erosion in disturbed areas that are expected to be re-disturbed or permanently seeded at a later date. It should be utilized as necessary to prevent erosion and decrease reliance on sediment control BMPs. <br />
<br />
Seeding and/or mulching will be a continuous operation on all cut and fill slopes, waste sites, and borrow areas during the construction process. Designated, disturbed areas shall be seeded and mulched when and where necessary to eliminate erosion. In designated areas seeding and/or mulching shall be done as soon as possible after completion of the earthwork, not to exceed 14 days (7 days on slopes steeper than 3:1), weather permitting.<br />
<br />
Temporary mulch placed over temporary seed mixtures shall be applied in accordance with the provisions of Sec 802.2.1 of the Missouri Standard Specifications. Fertilizer shall be applied at the rate specified for permanent seeding. Lime will usually not be required for temporary seeding but will be applied according to governing specifications when a permanent seed mixture is used.<br />
<br />
=====806.8.4.3.8.2 Permanent Seeding and Mulching (MO Specifications [http://www.modot.mo.gov/business/standards_and_specs/Sec0805.pdf Sec 805])=====<br />
<br />
Permanent seeding and mulching following the temporary seeding will be performed according to the Missouri Standard Specifications Sec 805 and ''will be permitted during the favorable seeding seasons only.'' It is important to remember that temporary seeding and mulching can be used to cover up bare soil during times that are not conducive to applying permanent seeding. Then, when conditions are more suitable for permanent seeding, it can be applied over/through the temporary seeding stubble. Or, in some cases, it may be necessary to mow the temporary seeding stubble and then apply permanent seeding.<br />
<br />
====806.8.4.3.9 Fiber Reinforced Matrix (FRM)====<br />
<br />
Fiber Reinforced Matrix (FRM) is a hydraulically applied (spray-on) erosion control product that bonds to, and blankets bare soil. It is typically applied with a truck or trailer mounted sprayer or by walking the affected areas with a hose sprayer. According to manufacturers, FRMs lock in moisture and nutrients to promote seed germination. Since these products are applied through spray-on application, they can conform to the contours of a slope and therefore can be applied to rough seedbeds. These products can be applied to all soil types on any slope and can be used in place of any of the erosion control blankets (ECBs) discussed in [[#806.8.4.3.10 Erosion Control Blankets and Turf Reinforcement Mats|EPG 806.8.4.3.10]], below. However, these products are only to be used as slope protection, and are not designed to withstand concentrated flows within ditches, drainages or streams. It is important when using these products to apply them according manufacturer’s specifications and to assure there is complete surface coverage on the affected area to prevent potential failure due to improper application. In order to accomplish this, it is important to spray slopes from multiple, varying directions. In some instances, especially on longer and/or steeper slopes, it may be necessary to install slope disruptors (wattles/socks/logs/etc.) perpendicular to the sheet flow to decrease runoff velocities down the face of the slope and protect the FRM application from concentrated flows. Manufacturer recommended application rates are summarized in the table below. Examples of FRMs include products such as Flexterra® Flexible Growth MediumTM, EcoFlexTM and Flex Guard®.<br />
<center><br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|-<br />
!align="center" style="background:#BEBEBE" width="200"|Slope Condition!!align="center" style="background:#BEBEBE"|Application Rate (lbs/Acre)<br />
|-<br />
|< 3H:1V ||3000<br />
|-<br />
|> 3H:1V and < 2H:1V ||3500<br />
|-<br />
|>2H:1V and < 1H:1V ||4000<br />
|-<br />
|>1H:1V|| 4500<br />
|}<br />
</center><br />
<br />
To ensure product quality and performance, all FRMs must meet the following specifications:<br />
<center><br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|-<br />
!style="background:#BEBEBE" colspan="3"|Minimum FRM Performance and Physical Requirements Property!! style="background:#BEBEBE"|Required Value <br />
|-<br />
|colspan="3" align="left" |Thermally Processed Fiber by Weight || 75% ± 10% <br />
|-<br />
|colspan="3" align="left" |100% bio-degradable Interlocking Fibers|| 5% ± 2% <br />
|-<br />
|colspan="3" align="left" |Organic Tackifiers and Activators || 10% ± 2% <br />
|-<br />
|colspan="3" align="left" |Moisture Content|| 10% ± 3% <br />
|-<br />
|colspan="3" align="left" |Organic Matter || 90% minimum <br />
|-<br />
|colspan="3" align="left" |Color|| width="250"|Colored to contrast application area, shall not stain concrete or painted surfaces. <br />
|-<br />
!colspan="2"|FRM Property !! Test Method !! Required Value <br />
|-<br />
|rowspan="6" |'''Physical''' ||align="left"| Mass Per Unit Area|| ASTM D6566*|| 12.0 oz/yd<sup>2</sup> minimum <br />
|-<br />
|align="left"|Thickness|| ASTM D6525*|| 0.22 in. minimum <br />
|-<br />
|align="left"|Ground Cover|| ASTM D6567*|| 99% minimum <br />
|-<br />
|align="left"|Wet Bond Strength|| ASTM D6818*|| 9 lb/ft <br />
|-<br />
|align="left"|Water Holding Capacity|| ASTM D7367|| 1500% minimum <br />
|-<br />
|align="left"|Flexural Rigidity (wet)|| ASTM D6575* || 5 oz-yd maximum <br />
|-<br />
|'''Endurance'''||align="left"| Functional Longevity|| ASTM D5338|| Minimum of 12 months <br />
|-<br />
|rowspan="4"|'''Performance'''||align="left"|Cover Factor|| MoDOT Approved Large Scale Testing || 0.01 maximum <br />
|-<br />
|align="left"|% Effectiveness || MoDOT Approved Large Scale Testing || 99% minimum <br />
|-<br />
|align="left"|Cure time|| MoDOT Approved Large Scale Testing||98% Effective 2 hours after application <br />
|-<br />
|align="left"|Vegetation Establishment || ASTM D7322*|| 800% minimum <br />
|-<br />
|rowspan="3"|'''Environmental||align="left"|Ecotoxicity|| EPA 2021.0|| 96-hr LC50 > 100%<br />
|-<br />
|align="left"|Effluent Turbidity|| MoDOT Approved Large Scale Testing|| 100 NTU Maximum<br />
|-<br />
|align="left"|Biodegradability|| ASTM D5338|| 100% Minimum<br />
|-<br />
|colspan="4" align="left" width="720"| '''*''' ASTM test methods developed for Rolled Erosion Control Products (RECPs) that have been modified to accommodate Hydraulic Erosion Control Products (HECPs). <br />
|}<br />
</center><br />
<br />
====806.8.4.3.10 Erosion Control Blankets and Turf Reinforcement Mats====<br />
<br />
Erosion control blankets (ECBs), erosion stabilization mats, and turf reinforcement mats (TRMs) are designed to reinforce vegetation. The added reinforcement allows the vegetation to withstand higher flow velocities and can be an alternative to rip rap applications. <br />
<br />
ECBs are typically used to prevent sheet, rill, or gully erosion on slopes and some lower flow channels. TRMs may be used on slope areas with concentrated flow, but are typically used in channels. Since ECBs have a limited life expectancy (longevity) they are considered to be "temporary" erosion control measures; however, most TRMs are composed of interwoven layers of geosynthetic materials such as polypropylene, nylon and PVC netting, which protects from both bio and photodegradation and allows for permanent vegetative reinforcement. At culvert outlets, overflow structures or transition areas, it may be necessary to use a transition mat (e.g., ScourStop™, ShoreMax™, etc.) directly over the TRM in order to add additional scour protection in these highly erosive areas.<br />
<br />
Slopes should be stabilized as soon as possible after grading work is completed. ECBs or TRMs should be considered for most slopes steeper than 3:1, depending on soil types. Protecting slopes from erosion requires several actions that must be taken together. No single approach will be successful, especially if the slope is long, steep, or has highly erodible soils.<br />
<br />
Mats and blankets will be installed as soon as practicable after final grading. Removal is not necessary or required seeing as how the material will decay and break down on its own or, in the case of TRMs, permanently reinforce the vegetation.<br />
<br />
Prior to installation of blankets or mats the ground should be smooth, with no large rocks, vegetation or rills on the surface. Areas where blankets are to be used shall be properly prepared with topsoil or soil conditioning, and fertilized if required, and seeded before blankets are placed. The blankets shall be placed smoothly but loosely on the soil surface without stretching. Blankets at the top of the slope should be trenched in beyond the crest of the slope so as to avoid undercutting. Blankets and mats should be inspected at the same frequency as all other erosion and sediment control items. Malfunctions must be repaired in a timely manner or else slope shaping, grading and reinstallation will be required. <br />
<br />
Products meeting the requirements outlined within the tables below each have their own physical description that can be obtained from the manufacturer. Providing the physical description of all ECBs or TRMs would be unnecessary and redundant for the purposes of this SWPPP. <br />
<center><br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+'''Guidelines for Erosion Control Blankets (ECBs)'''<br />
!style="background:#BEBEBE" |MoDOT ECB Type!! style="background:#BEBEBE"|Netting !! style="background:#BEBEBE"|Longevity !! style="background:#BEBEBE"| Slopes !! style="background:#BEBEBE"| Soils<br />
|-<br />
|Type 1|| Single Net, Quickly Degradable|| 45 – 60 Days|| 3:1 or Flatter|| Clay<br />
|-<br />
|Type 2|| Single Photodegradable Net ||12 Months ||3:1 or Flatter ||Sandy<br />
|-<br />
|Type 3|| Double Photodegradable Net|| 12 – 18 Months|| 2:1 or Flatter|| Clay<br />
|-<br />
|Type 4|| Double Photodegradable Net|| 24 Months|| 2:1 or Flatter|| Sandy<br />
|-<br />
|Type 5|| Double Photodegradable Net|| 36 Months|| 1:1 or Flatter ||Any<br />
|}<br />
</center><br />
<br />
'''Guidelines for Turf Reinforcement Mats (TRMs)'''<br />
:'''Type 1 Turf Reinforcement Mat'''<br />
::• Channels: Calculated Shear Stresses of 3.5 lbs/ft<sup>2</sup> to 6 lbs/ft<sup>2</sup><br />
<br />
:'''Type 2 Turf Reinforcement Mat'''<br />
::• Channels: Calculated Shear Stresses of 6.1 lbs/ft<sup>2</sup> to 8 lbs/ft<sup>2</sup><br />
<br />
:'''Type 3 Turf Reinforcement Mat'''<br />
::• Channels: Calculated Shear Stresses of 8.1 lbs/ft<sup>2</sup> to 10 lbs/ft<sup>2</sup><br />
<br />
:'''Type 4 Turf Reinforcement Mat'''<br />
::• Channels: Calculated Shear Stresses of 10.1 lbs/ft<sup>2</sup> to 14 lbs/ft<sup>2</sup><br />
<br />
:(Note: Use Erosion Control Blanket for Calculated Shear Stresses up to 3.5 lbs/ft<sup>2</sup> and use Turf Reinforcement Mat for Calculated Shear Stresses of 3.5 lbs/ft<sup>2</sup> or greater.)<br />
<br />
<br />
===806.8.4.4 Sediment Control Measures===<br />
<br />
As previously stated, the emphasis on MoDOT projects should be erosion control and focusing on covering up exposed soil, preferably with permanent vegetation, rock, pavement, etc., as soon as practicable in order to protect the soil surface and keep soil particles from dislodging and entering stormwater. While erosion control should be the primary focus, it is important to back up erosion control efforts with appropriate and effective sediment control. Sediment control is most effective when incorporated with a system of structural BMPs (treatment train) and efforts are focussed on combatting sediment as close to its source as possible. The following sediment control measures should be used in combination to treat stormwater and minimize sediment loss from MoDOT projects. <br />
<br />
====806.8.4.4.1 Sediment Basin====<br />
<br />
A sediment basin is a large sediment capturing device that can be constructed through excavation, or by constructing a dam across a low drainage swale. Sediment basins can be temporary or permanent. Both permanent and temporary basins, with expected prolonged use, should be constructed with rock riprap placed in inlet and outlet areas with defined side slopes (see [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf MoDOT Standard Plan 806.10]). Temporary sediment basins intended for short-term use do not have to be constructed according to the MoDOT standard plan, but will always have stabilized outlets consisting of rock, a riser pipe or a surface skimmer (e.g., Faircloth Skimmer®), all designed to discharge water from the surface of the basin. Sediment basins are constructed to trap and store sediment from erodible areas in order to protect properties and stream channels below the installation from excessive siltation. To add additional sediment removal capability to basins, baffles can be designed within the basin to slow stormwater flow and increase treatment time within the basin. Basically, the longer the water takes to get from the inlet of the basin to its outlet, the more effective the treatment and the better the water quality at the outfall.<br />
<br />
Sediment basins are required (unless infeasible due to site constraints) when large disturbed areas (>10 acres) concentrate flow to one discharge point, but they should be considered for any disturbed area, 5 acres or greater, which drains to one discharge point. The area where a sediment basin is to be constructed shall be cleared of vegetation to enable removal of sediment. The inlets of these sediment basins shall be constructed with a wide cross-section and minimum grade to prevent turbulence and allow deposition of the soil particles. Upon construction of the basin, the side slopes of the basin should be seeded down with either annual or perennial vegetation or otherwise stabilized to protect the slopes from erosion. When the depth of sediment reaches 1/2 of the depth of the structure in any part of the pool, all accumulation shall be removed. Discharges from the basin shall not cause scouring of the receiving area or stream. <br />
<br />
The location of sediment basins will be shown on the plans. Sediment basins should be designed to a sufficient size to contain a volume of at least a 2-year, 24-hour storm for the area draining to the basin, or, if this calculation has not been performed, then a basin should be designed to contain a volume of 3,600 cubic feet per each acre of disturbed area which drains to the basin. Where the use of a sediment basin of sufficient size as described above is impractical it should be documented in the SWPPP and other similarly effective BMPs or system of BMPs must be employed to minimize sediment loss from MoDOT right of way. These similarly effective BMPs or systems could include, but are not limited to sediment traps, ditch checks, type C berms, etc., and the use of appropriate erosion control items to cover up exposed soil. An explanation of why these similarly effective BMPs were selected instead of a basin should be documented in the project SWPPP. <br />
<br />
Sediment basins should be installed at the time of clearing and grubbing, and will normally remain in service until all disturbed areas draining into the structure have been satisfactorily stabilized. Once vegetative or other stabilization is achieved, the engineer will determine whether the sediment basin is to remain as a permanent feature. When use of the sediment basins is to be discontinued, all excavations are to be backfilled and properly compacted, fill material removed, and the existing ground restored to its natural or intended condition.<br />
<br />
When accumulated sediment is removed from individual BMPs, the excavated material shall be disposed of in locations where sediment will not again erode into the construction areas or into natural waterways.<br />
<br />
====806.8.4.4.2 Sediment Trap ====<br />
<br />
A sediment trap is a temporary sediment collection structure that is used for sediment control purposes. If properly maintained, the life expectancy of these structures can be approximately 2 years. When practical, sediment traps should be installed prior to land disturbance activities. In situations where long-term maintenance issues are absent, and permanent vegetation has established, sediment traps may be left in place as a permanent structure as long as there is no threat to the natural or human environment. <br />
<br />
Sediment traps may be constructed of rock (as per the MoDOT Standard Plans) or other non-erodible material sufficient to temporarily impound water, or may be a simple excavated pit. They are usually placed down grade of a drainage structure or ditch outlet to prevent sediment from leaving MoDOT right of way. Sediment traps may also be constructed by placing a rigid, blocking structure (wood, steel, concrete) across the inlet or upstream opening of a pipe or culvert. This device can be referred to as a culvert block sediment trap (CBST). When using this device, heavy sediment particles will settle in front of the structure and clearer water will pass over the device and through the pipe.<br />
<br />
Around larger, more permanent streams, sediment traps should be placed parallel to the stream at each ditch outlet. They will be in place prior to clearing and grubbing operations and shall remain in place until adequate stabilization to prevent erosion (vegetative cover, rock, concrete, etc.) is established upgrade of the structures.<br />
<br />
Sediment traps may be dewatered through a single riser pipe, over a stabilized spillway (rock-lined, lined with erosion control blanket or turf reinforcement matting, vegetated), or, where applicable, allowed to filter through the interstices of a constructed rock barrier. <br />
<br />
The location of sediment traps will be shown on the inspector's site plans. Accumulated sediment shall be removed from the trap when sediment has accumulated to 1/2 the height of the structure, or if an excavated pit, 1/2 of the original depth. Accumulated sediment removed from the sediment traps shall be disposed of in locations where sediment will not again erode into the construction areas or into natural waterways. Discharges from the sediment trap shall not cause scouring of the receiving area or banks or bottom of the receiving stream.<br />
<br />
Traditional rock sediment traps will be constructed in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf MoDOT Standard Plan 806.10] and [http://www.modot.mo.gov/business/standards_and_specs/Sec0806.pdf Sec 806.60]. Estimated quantities for each trap located on the project will be shown to the nearest cubic yard.<br />
<br />
====806.8.4.4.3 Ditch Checks====<br />
<br />
Ditch checks are also considered as erosion control measures.<br />
<br />
MoDOT has two categories of ditch checks: rock and alternate ditch checks. These erosion and sediment control structures are typically used when the road ditch has been "cut" or "rough cut" to its final or near final dimensions, before the application of seed and mulch; however, they may also be installed prior to achieving final ditch grade in order to prevent erosion and protect from sediment loss. <br />
<br />
'''Rock Ditch Checks''' are the predominant ditch check to be used on MoDOT projects. Rock ditch checks can be specified in most drainage areas where ditch slopes are 10 percent or less, and where expected ditch flow volumes and velocities are high (see MoDOT [http://www.modot.org/business/standards_and_specs/documents/80610.pdf Standard Plan 806.10]). For scenarios that exceed the criteria established above, a combination of rock ditch checks and erosion control blankets (ECBs) or turf reinforcement mats (TRMs) should be utilized. (Note: ECBs or TRMs may be designed into and utilized in any ditch or drainage regardless of the criteria outlined in this article.)<br />
<br />
Rock ditch checks will typically be composed of rock with a predominant size between 4 in. and 12 inches, but this size may be adjusted to incorporate larger sizes if site conditions warrant. In areas of clay soils, where additional filtration may be needed, the upgrade face of the check can be capped with smaller stone, filter fabric or another approved filtering media. <br />
<br />
As a general rule, the last ditch check in a system of ditch checks, prior to discharging from MoDOT right of way, should be a well-constructed rock ditch check or a sediment trap. These devices tend to withstand heavy flows and have a greater volume for impoundment.<br />
<br />
Alternate Ditch Checks should be considered as an alternate to rock ditch checks in areas where there are safety concerns for the traveling public or other constraints where there would be concern with installing rock. These devices can typically be used in smaller drainage areas, with ditch slopes of 4 percent or less, and where expected ditch flow volumes and velocities are small (see MoDOT Standard Plan 806.10). These thresholds may be exceeded at the approval of the engineer. <br />
<br />
Alternate ditch checks should have an effective height of at least 9 inches and should be installed in accordance with the manufacturer’s recommendations or as outlined in this SWPPP.<br />
<br />
Alternate Ditch Checks can include the following or other engineer approved devices:<br />
<br />
::Triangular Silt Dike®<br />
::EnviroBerm® Porous Sediment Control System (In combo with ECB or TRM)<br />
::GeoRidge/GeoRidge Biodegradable (Nilex) (In combo with ECB or TRM)<br />
::Compost Filter Berms (1’(H) x 2’(W)) (Covered with biodegradable ECB/TRM)<br />
::Sand Bags<br />
::Fiber Rolls, Sediment Logs, Compost Filter Socks – staked and > 9” effective height and must be used in combination with ECBs or TRMs as a channel liner beneath. <br />
<br />
::'''(IMPORTANT: Straw wattles, straw bales and geotextile silt fence are no longer acceptable as a ditch check BMPs.)'''<br />
<br />
Each type of ditch check (particularly the tubular/cylindrical/triangular products) will have specific directions for installation. In all cases care shall be exercised so as to install the device according to manufacturer specifications. Effectiveness may be compromised if not installed correctly.<br />
<br />
Ditch checks shall be placed and constructed according to the plans (see MoDOT Standard Plan 806.10). In some cases local conditions may dictate some deviation from the dimensions and shape that are shown in the Standard Plans; however, deviations from Standard Plans must still ensure that sediment capture and erosion control is occurring. <br />
<br />
Ditch checks shall be checked for sediment accumulation after each runoff event. Sediment shall be removed when it reaches 1/2 of the original height, or before. Sediment removal will include removal and disposition in a location where it will not erode into construction areas or watercourses. Inspections shall be made to ensure that the center of the check is lower than the edges. This will ensure that water overflow will be directed into the middle of the roadway ditch. Erosion caused by high flows around the edges of the ditch check shall be identified in routine inspections and shall be corrected so as to protect backslopes and inslopes, as well as the effectiveness of the BMP.<br />
<br />
Ditch checks shall remain in place until the engineer directs that they be removed once adequate stabilization (vegetative cover, rock, concrete, etc.) upgrade of the structures has been achieved in accordance with the permit. Upon removal, the contractor shall remove and dispose of any excess silt accumulations, grade and dress the area to the satisfaction of the engineer, and establish stabilization on all bare areas. As a general rule for rock ditch checks, once the area has reached final stabilization, any collected sediment should be removed and rock ditch checks can be graded out within the ditch line, serving a similar purpose as a liner. In rare cases, rock ditch checks may remain in place permanently, and resultant accumulated sediment shall be allowed to develop vegetative cover as a permanent feature of the right of way. Similarly, biodegradable structures and their accumulated sediment may be allowed to remain in place if the engineer determines that removal will destabilize the ditch. In cases of compost, mulch, etc. filled checks, the wooden stakes should be pulled and the biodegradable netting cut to encourage more rapid degradation. If the netting is non-biodegradable, the netting shall be cut and removed along with the stakes, but the biodegradable filling may be left to decompose.<br />
<br />
====806.8.4.4.4 Silt Fence (MO Specifications [http://www.modot.mo.gov/business/standards_and_specs/Sec0624.pdf Sec 624] and [http://www.modot.mo.gov/business/standards_and_specs/Sec1101.pdf 1011])====<br />
<br />
Use of a silt fence consists of furnishing, installing, maintaining, and removing a geotextile barrier fence designed to remove suspended particles from water passing through the fence. Silt fence is a temporary sediment control measure. Materials used for silt fences must meet certain requirements.<br />
<br />
There are several construction requirements for silt fences. Fence construction shall be adequate to handle the stress from hydraulic and sediment loading. Geotextile at the bottom of the fence shall be buried. The trench shall be backfilled and the soil compacted over the geotextile. The geotextile shall be spliced together as indicated on the standard drawings (see MoDOT [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf MoDOT Standard Plan 806.10]).<br />
<br />
As a general rule, geotextile silt fence, especially non-wire reinforced geotextile silt fence, should not be used as inlet protection, particularly around culvert and drop inlets where high volume, concentrated flows are expected, except in the instance described in [[#806.8.4.4.5 Inlet Controls|EPG 806.8.4.4.6 Inlet Controls]]. Geotextile silt fence is also not appropriate for use as ditch checks.<br />
<br />
Post spacing shall not exceed 8 ft. for wire-backed fence installations or 5 ft. for self-supported installations. Posts shall be driven a minimum of 24 in. into the ground. Where rock is encountered, posts shall be installed in a manner approved by the engineer, or another alternative BMP may be selected. Closer spacing, greater embedment depth and/or wider posts shall be used as necessary in low areas and soft or swampy ground to ensure adequate resistance to applied loads. In low swales, where concentrated flows may form, consider using a ditch check in lieu of silt fence. If heavy sediment or runoff loading is expected against the silt fence, the use of metal “T” posts should be considered in lieu of wooden post stakes.<br />
<br />
When wire support fence is used, the support wire shall be fastened securely to the up-slope side of the post. The support wire shall extend into the trench a minimum of 2 in. and extend a maximum of 36 inches above the original ground surface. When self-supported fence is used, the geotextile shall be securely fastened to fence posts.<br />
<br />
When silt fence is used as a perimeter sediment control device it will generally be installed at the time of clearing and grubbing, and must be maintained for as long as necessary to contain sediment from runoff. Silt fence should be installed on the contour when possible to prevent overtopping or overloading at single points. If it is run down a grade, parallel to runoff flow, J-hooks should be installed into the silt fence system to dissipate energy and capture runoff so as to not overwhelm the system at a low point. All silt fences shall be inspected as part of MODOT’s routine inspections. It is also recommended that casual daily inspections be made during periods of prolonged rainfall. <br />
<br />
In addition, review of the location of silt fences should be made in areas where construction activities have changed the natural contour and drainage runoff to ensure that the silt fences are properly located for effectiveness. Where deficiencies exist, additional silt fences, or another appropriate BMP shall be installed as approved or directed by the engineer. If silt fence is no longer necessary in an area, it should be removed to negate maintenance and liability.<br />
<br />
Sediment deposits shall be removed and disposed of when the deposit approaches 1/2 the height of the fence or sooner. If required by heavy sediment loading, a second silt fence shall be installed as directed by the engineer. Installation of a second silt fence will sometimes preclude sediment cleanout or repair to the original silt fence. In such cases the damaged silt fence will be removed at project close out when other temporary BMPs are removed. <br />
<br />
The silt fence shall remain in place until areas that drain to the fencing are stabilized in accordance with the permit and the engineer directs that it be removed. Upon removal, the contractor shall remove and dispose of any excess silt accumulations, grade and dress the area to the satisfaction of the engineer, and establish vegetation on all bare areas. Biodegradable silt fence (such as some of the example products listed below) need not be removed. If the engineer determines that silt fence shall remain in place for a period of time after the job is closed out, arrangements will be made by MoDOT Construction personnel for the contractor or MoDOT Maintenance personnel to remove the fence once the area is sufficiently stabilized in accordance with the permit.<br />
<br />
At the discretion of the engineer the following product examples or other approved BMPs may be substituted for perimeter geotextile silt fence. These devices should be installed in accordance with manufacturer recommendations. In the case of the wattles, socks and log devices, if practical and possible, a cradle trench should be created to lay the product in to ensure proper contact with the ground surface. This may not be appropriate if installing these devices in areas with existing grass cover, such as yards, or in areas with shallow utilities or bedrock beneath; however, care should be taken to ensure flush contact with the ground surface. Thought should also be put into product choice based on expected longevity, as some devices listed below will decompose or break down more quickly than others, and may require replacement or multiple replacements during the life of a job. In general, perimeter silt fence installations should have a minimum of 9” in effective height unless site conditions warrant a higher or lower effective height.<br />
<br />
Example Products:<br />
::Sediment STOP <br />
::Terra-Tubes <br />
::Sediment Logs, Wattles<br />
::Compost Filter Socks/Berms<br />
::Triangular Silt Dike<br />
<br />
====806.8.4.4.5 Rock/Mesh Sediment Control Fence and Inlet Protection Device==== <br />
<br />
In situations when higher velocity stormwater flows are expected around the perimeter of a construction site, a rock/mesh sediment control fence should be installed in lieu of geotextile or other silt fence applications. This device is constructed using a 4 ft. wire mesh (hardware cloth – 24 gauge, ¼ in. openings) folded in half to form a 90° angle. This mesh is then wired to, and supported by 5 ft. metal “T” posts spaced 3 ft. apart and driven approximately 2 ft. into the ground. Lastly, a layer of #5 or #57 stone is placed against the mesh, with a minimum height of 12 in., but preferably 18 inches.<br />
<br />
Use this device in lieu of other silt fence applications at the toe of fill sections, especially along streams and wetlands and in other areas where there is insufficient right of way to construct better impoundment devices, such as sediment basins or sediment traps. As with silt fence applications, the sediment control fence should be placed perpendicular to stormwater flow, allowing the water to pass either over or through the rock/mesh sediment control fence, never around it.<br />
<br />
This same device can be modified for use around drop inlets, creating a closed ring or box around the inlet opening using the same installation guidelines outlined above.<br />
<br />
Rock/mesh sediment control fences shall be inspected during weekly and post-runoff inspections for structural damage, undercutting, sediment buildup, or lack of drainage due to sediment clogged stone. Sediment deposits shall be removed and disposed of when the deposit approaches 1/2 the height of the fence or sooner. Accumulated sediment removed from the fence shall be disposed of in locations where sediment will not again erode into the construction areas or into natural waterways. Also, if the filter stone becomes sediment-clogged and no longer serves as a filter, it may be appropriate to replace it with new stone. <br />
<br />
The rock/mesh sediment control fence shall remain in place until areas that drain to the fencing are stabilized and the engineer directs that it be removed. Upon removal, the contractor shall remove and dispose of any excess sediment accumulations, grade and dress the area to the satisfaction of the engineer, and establish vegetation on all bare areas. If the engineer determines that sediment control fence shall remain in place for a period of time after the job is closed out, arrangements will be made by MoDOT Construction personnel for the contractor or MoDOT Maintenance personnel to remove the fence once the area is sufficiently stabilized.<br />
<br />
====806.8.4.4.6 Inlet Controls====<br />
<br />
Storm drain (culvert, drop or curb) inlet protection measures prevent soil and debris from entering storm drain inlets. Temporary inlet protection is implemented at existing inlets prior to land disturbance, and new inlets are to be protected as they are put into service. Effective storm drain inlet protection must be provided for all inlets susceptible to receiving sediment throughout the project until all sources with potential for discharging to an inlet have been paved or stabilized. At that time inlet controls can be removed. <br />
<br />
As the conditions or operations change during a project, the sediment control BMP protecting the storm drain inlet may need to be modified to ensure proper effectiveness for sediment filtration and capture. Also, limiting the amount of sediment entering a storm sewer will reduce the need to clean out pipes at the end of the project.<br />
<br />
The following types of items are generally considered for use as inlet protection:<br />
<br />
Curb Inlet Protection:<br />
<br />
::* Sand Bags/Rock Socks<br />
::* Wattles/Compost Filter Socks/Fiber Rolls/Sediment Logs, etc.<br />
::* Various Filter Inserts (e.g., but not limited to, Silt Saver Inlet Filter & Big Red Curb Inlet Protector, Dandy Products (Bag, Sack, Pop, Curb, Curb Bag, Curb Sack))<br />
::* Wood, Steel or Other Barricades<br />
<br />
Drop or Pipe/Box Inlet Protection (Should have 9 in. effective height):<br />
<br />
::* Rock/Mesh Inlet Check (NEW – see [[#806.8.4.4.5 Rock/Mesh Sediment Control Fence and Inlet Protection Device|EPG 806.8.4.4.5 Rock/Mesh Sediment Control Fence and Inlet Protection Device]])<br />
::* Rock Ditch Checks<br />
::* Triangular Silt Dike®<br />
::* Sand Bags<br />
::* Compost Filter Berms<br />
::* Various Filter Inserts (e.g., but not limited to, Silt Saver Inlet Filter and Big Red Area Inlet Protector, Dandy Products (Bag, Sack, Pop, Curb, Curb Bag, Curb Sack))<br />
::* Wood (CBST, as discussed in [[#806.8.4.4.2 Sediment Trap|EPG 806.8.4.4.2 Sediment Trap), Steel or Other Barricades<br />
<br />
::(Note: Item selection may vary depending on the type and design of inlet to be protected and careful consideration should be made with inlet protection to ensure any impounded water will not flood streets, buildings, homes, etc..)<br />
<br />
As a general rule, geotextile silt fence, especially non-reinforced geotextile silt fence, should not be used as inlet protection, particularly around culvert and drop inlets where high volume, concentrated flows are expected. An exception to this is if a constructed wood or steel frame is erected around the inlet and this frame is then wrapped with geotextile material. In this application, it is recommended for additional support and protection that wire reinforcement be wrapped around the frame and then the geotextile applied over the wire.<br />
<br />
Each type of inlet control device (particularly the tubular/cylindrical/triangular products) will have specific directions for installation. In all cases care shall be exercised so as to install the device according to the manufacturer's specifications. Effectiveness may be compromised if not installed correctly.<br />
<br />
During construction, elevated curb inlets and median inlets, as well as excavations around inlets, may serve as "riser pipes" as long as they are sufficiently higher (approximately 9 in. or more) than the existing grade. Sediment that accumulates at the base of the riser pipe following stormwater events shall be removed when it reaches 1/2 of the original height of the riser pipe. Once the desired grade has been achieved and the inlet becomes flush to that grade, subsequent inlet protection is required.<br />
<br />
====806.8.4.4.7 Temporary Berms — Sediment Control====<br />
<br />
Type C berms are specified at the toes of spill slopes around bridge construction operations and will usually be constructed to the specified dimension (see [http://www.modot.mo.gov/business/standards_and_specs/documents/80610.pdf MoDOT Standard Plan 806.10]). However, dimensions may deviate from those shown on the standard drawings based on site limitations. Also, the straw layer or erosion control blanket may be removed if the character of the rock material is sufficient to prohibit contaminated water from reaching the stream. Installation will generally precede land disturbance activities, unless some clearing is necessary in order to gain access to the site. Type C Berms must be installed above the regulatory "ordinary high water mark" and will be installed at the location specified by the engineer. The structure may be permanent or temporary depending on the ultimate desired use of the right of way beneath the bridge. If the Type C Berm is removed, material may be used for bank stabilization, or other construction use. Bank stabilization will be in accordance with Section 404 permit. Type C Berms shall be checked for sediment accumulation after each runoff event. Sediment shall be removed when it reaches 1/2 of the original height or before. Sediment removal will include removal and disposition in a location where it will not erode into construction areas or watercourses. <br />
<br />
(Note: Oftentimes temporary stream crossings are used in proximity to Type C berms. These crossings can cause gaps in the berm for equipment passage, which could potentially be a conduit for sediment delivery to the waterbody. Use caution when using these two practices in the same location and assure adequate protection of the waterbody. Refer to [[#806.8.4.3.6 Temporary Pipes and Temporary Construction Crossings|EPG 806.8.4.3.6 Temporary Pipes and Temporary Construction Crossings]] for more information.)<br />
<br />
Type A Berms may be used as a temporary perimeter control structure where slopes are less than 2% and permanent vegetation is present on the downgrade side of the structure. They will be constructed to specified dimensions (see MoDOT Standard Plan 806.10) and will be machine compacted with a minimum of one pass over the entire width of the berm with a dozer tread, grader wheel, etc. When used as a perimeter control BMP, weekly (and post-rainfall) monitoring will be necessary to identify breeches. Removal of Type A Berms will occur when grading operations cease and final contours are achieved. Removal will usually occur just before the application of seed and mulch or other soil stabilization measures.<br />
<br />
====806.8.4.4.8 Compost Filter Berms (Mulch Berms Included)====<br />
<br />
A compost filter berm is a temporary dike of compost or a compost product that is placed perpendicular to sheet flow runoff to control erosion in disturbed areas and retain sediment. It can be used in place of a traditional sediment and erosion control tool such as silt fence. As such these berms are installed at the time of clearing and grubbing and will remain in place throughout construction. Composts used in filter berms are made from a variety of feedstocks, including municipal yard trimmings, food residuals, separated municipal solid waste, biosolids, wood chips, and manure.<br />
<br />
Compost filter berms are generally placed along the perimeter of a site, or at intervals along a slope, to capture sediment from sheet flow. A filter berm can also be used as a check dam in small drainage ditches as described in [[#806.8.4.4.3 Ditch Checks|EPG 806.8.4.4.3 Ditch Checks]]. <br />
<br />
Post-construction removal is not required because, by definition, they are biodegradable and temporary. However, unvegetated berms are often broken down once construction is complete and the compost is sometimes spread around the site as a soil amendment or mulch.<br />
<br />
====806.8.4.4.9 Brush Pile Checks/Barriers====<br />
<br />
Brush pile checks or barriers are considered to be temporary BMPs that can be effective during clearing and grubbing operations. Piled and compressed tree tops, limbs, stumps and other vegetation, when placed in a ''' "non-jurisdictional" ''' drainage swale or around the perimeter of a land disturbance site, can effectively impound gravel, soil and other eroded materials that otherwise may be carried off of MoDOT right of way during runoff periods. To be effective, brush piles should be compressed tight to the ground by clearing equipment at the time of installation so there is no void beneath. Brush checks and barriers are only intended to operate as stand-alone BMPs for a very short time period during initial clearing and grubbing, and should be bolstered by the installation of additional supportive measures upgrade or downgrade of the structures, such as sediment basins, sediment traps, ditch checks, etc., as soon as practicable. When these other devices are installed, the brush check/barrier may be left in place as additional filtration, if permissible, or removed.<br />
<br />
Like other BMPs, brush piles should be inspected during required inspections to ensure that they are functioning as intended. Initial inspections following rainfall will determine their ability to impound water and sediment. If the brush pile is intended to serve as a longer term sediment control structure for an extended period of time beyond the clearing and grubbing stage, clean out and maintenance equivalent to that required for ditch checks is required.<br />
<br />
After land disturbance has been completed, removal should be discussed before heavy equipment leaves the site. In rural situations, and where maintenance issues are absent, the brush pile may be abandoned and left to decompose on its own. <br />
<br />
====806.8.4.4.10 Straw Bales (MO Specifications [http://www.modot.mo.gov/business/standards_and_specs/Sec0802.pdf Sec 802)]====<br />
<br />
The use of straw bales as sediment control devices should be avoided on MoDOT projects. However, due to the extremely short duration of the operation and the nature of the discharge, straw bales can be used as checks to control discharge slurry from diamond grinding operations as described in [[#806.8.11 Diamond Grinding and Other Surface Treatments|EPG 806.8.11 Diamond Grinding and Other Surface Treatments]]. During diamond grinding operations, the straw bales are typically used in concert with other BMPs, including non-structural BMPs such as existing vegetation or mulch.<br />
<br />
In these situations, bales of straw can be installed as ditch checks and used as a temporary means of controlling pollution by obstructing the flow of the slurry and allowing deposition of the fine cement particles. The bales should be properly staked and extend far enough up the inslope and backslope to sufficiently impound the discharge slurry. The integrity of straw bales must be maintained for as long as they are necessary to contain the slurry. When no longer necessary to control pollution, the bales and other temporary BMPs associated with diamond grinding operations should be removed.<br />
<br />
==806.8.5 Disturbed Areas==<br />
<br />
Project plans that are discussed in [[806.8 Storm Water Pollution Prevention Plan (SWPPP)#806.8.2 Site Description|EPG 806.8.2 Site Description]] will identify those areas that will be cleared and graded as part of the highway development project. The plans will also identify areas that are not to be disturbed. Both disturbance and do not disturb areas are generally staked in the field. <br />
<br />
On areas of the site where soil disturbing activities will cease and are not planned to resume for a period exceeding 14 calendar days, temporary stabilization must be initiated immediately upon knowing of the 14-day cessation, and must be completed within 7 calendar days. On portions of the project where slopes are greater than 3:1 (1V:3H), or greater than 3% and longer than 150 ft., all temporary stabilization must be completed within 7 days of ceasing operations. Temporary stabilization may include, but is not limited to the installation of sediment basins, check dams, sediment fences, and mulch; however, the preferred method of stabilization is seed and mulch.<br />
<br />
[[:Category:805 Seeding|Seeding]] and/or [[:Category:802 Mulching|mulching]] will be a continuous operation on all cut and fill slopes, [[:Category:135 The Section 106 Process#135.3 Borrow and Excess Material Areas|excess material sites, and borrow areas]] during the construction process. <br />
<br />
All disturbed areas should be seeded and mulched or otherwise stabilized when and where necessary to eliminate erosion. Seeding and/or mulching shall be done as soon as possible after completion of the earthwork and preparation of the seedbed, weather permitting. <br />
<br />
Whenever clearing, grading, excavating or other earth disturbing activities have permanently ceased on a portion of the site, final stabilization must be initiated immediately and completed within 7 calendar days. Final stabilization can be achieved by covering disturbed areas with pavement, buildings or other structures, perennial vegetation or non-erodible materials such as adequately sized rock. With respect to areas that have been seeded, vegetation cover must be at least 70% plant density with uniform coverage over 100% of the disturbed area.<br />
<br />
For the purposes of this section, allowances to the 7-day completion period for temporary and permanent stabilization may be made due to inclement weather or adverse site conditions. If utilized, these allowances must be properly documented in the project SWPPP, including pictures. <br />
<br />
The following types of activities will constitute initiation of stabilization (this list is not exhaustive):<br />
<br />
:* Prepping the soil for vegetative or non-vegetative stabilization<br />
:* Applying mulch or other non-vegetative product to the exposed area<br />
:* Seeding or planting the exposed area<br />
:* Starting any of the above activities on a portion of the area to be stabilized, but not on the entire area<br />
:* Finalizing arrangements to have stabilization product fully installed in compliance with the applicable deadline for completing stabilization<br />
<br />
Note: the term “immediately” in this subarticle means as soon as practicable, but no later than the end of the next work day, following the day when the earth-disturbing activities have temporarily or permanently ceased.<br />
<br />
==806.8.6 Installation and Removal==<br />
<br />
The contractor shall be required to incorporate all permanent erosion control measures into the project at the earliest practicable time. As stated in [[#806.8.4.1 Construction Requirements|EPG 806.8.4.1 Construction Requirements]], when practical, border, perimeter or outlet BMPs to control runoff from disturbed areas shall be installed or marked for preservation before general site clearing. A limited amount of clearing may be permissible to enable the installation of outlet and perimeter controls. Stormwater discharges from disturbed areas, which leave the site, shall pass through and appropriate impediment prior to leaving the site. It may be necessary to install additional control measures during construction which were not foreseen during the design stage. Temporary erosion control shall also be used when needed prior to installation of permanent erosion control measures or when needed temporarily to control erosion that develops during normal construction practices, but are not associated with permanent control measures on the project.<br />
<br />
Temporary BMPs should be removed from the project when areas they are protecting have achieved final stabilization in accordance with the permit. Oftentimes engineers and/or contractors may desire to leave all temporary BMPs in place until project completion and then have one mass removal. Though this practice is not ideal due to increased vulnerability, it is acceptable if the BMPs are continuously inspected and maintained in accordance with the permit until their removal. Also, if the engineer determines that some BMPs shall remain in place for a period of time after the job is closed out, arrangements will be made by MoDOT Construction personnel for the contractor or MoDOT Maintenance personnel to remove the BMPs once the area(s) they are protecting are sufficiently stabilized.<br />
<br />
==806.8.7 Dewatering==<br />
<br />
Dewatering of ponds, lakes, coffer dams, pits or excavations associated with construction shall be discussed at the preconstruction conference, and articulated in a written plan, which will outline a method for properly treating the water before it can re-enter a river, stream, pond, lake, wetland, etc. This plan may be amended at any time if changes are necessary. <br />
<br />
[http://www.modot.mo.gov/business/standards_and_specs/Sec0107.pdf Standard Specification 107.10.2] requires a dike or appropriate barrier to be placed between the excavation and the stream to prevent sediment from reaching the watercourse. The structural BMPs that are identified in [[#806.8.4.4 Sediment Control|EPG 806.8.4.4 Sediment Control Measures]] are usually sufficient to remove sediment and similar pollutants prior to discharge of return water. Land application of the discharge water is a viable option when percolation into the subsurface results; however, caution shall be used to ensure that water discharge does not cause the formation of gullies in cases where pumping exceeds percolation.<br />
<br />
With the possible exception of drilled shafts in large rivers such as the Missouri or Mississippi, return water shall not be discharged without treatment by BMPs that are approved by the engineer. The amount of return water that is pumped and subsequently discharged should be recorded in the project records and expressed as gallons per minute for the duration of the pumping activity.<br />
<br />
==806.8.8 Roadways==<br />
<br />
In order to ensure that sediment is not transported into a situation where it can be delivered off-site, stabilized construction entrances should be used when construction equipment is frequently crossing or entering paved roadways. Stabilized construction entrances should be built with rock of sufficient size to cause mud and dirt to fall off of the tires of the construction equipment. Geotextile fabric may be necessary for placement below the stabilized entrance in some soil conditions to prevent the rock entrance from subsiding into the soil. In muddy situations, the voids between the rocks will always fill up with soil particles and as such, additional stone will need to be applied periodically and when repair is required.<br />
<br />
The purpose of the stabilized entrance is to reduce the amount of sediment that will be transported onto the driving surface. However, the driving surface at the point of the active crossing cannot remain clean without additional measures such as sweeping or grading.<br />
<br />
Because it is impossible to eliminate all trackout of soil particles, inspections should ensure that sediment control measures downgrade from the area of trackout are in good operating condition, especially inlet controls. <br />
<br />
On projects where there is one primary construction entrance/exit and a large volume of equipment is expected to pass through this point, a more structural BMP may be appropriate to handle the volume of sediment. If this is the case, rumble strips, cattle guards, or wheel wash stations may be employed to effectively remove sediment. In these situations, routine maintenance will be needed to remove accumulated sediment from beneath and/or around these structures. If a wheel wash system is used, wash water should be channeled to a constructed sediment trap for treatment, unless the system has the capability to recycle the wash water. Just as with other sediment traps, once installed, the location of the trap will be shown on the inspector's site plans. Accumulated sediment shall be removed from the trap when the accumulation reaches 1/2 the height of the structure, or if an excavated pit is used, 1/2 of the original depth.<br />
<br />
When accumulated sediment is removed from these BMPs, the material shall be disposed of in locations where sediment will not erode into the construction areas or into natural waterways.<br />
<br />
==806.8.9 Amending/Updating the Project Plans==<br />
<br />
Erosion control plans are prepared by MoDOT designers and/or consultants. There should generally be two sets of plans developed. One set should be developed to depict existing site topography with outfall and perimeter protection BMPs such as sediment basins, sediment traps, Type C berms, silt fence, etc., that will need to be installed prior to starting land disturbance of the site. The second set will generally show final structural BMPs that are envisioned upon completion of final grading. However, due to project phasing, all of these devices will not be installed until needed, based on site conditions. Therefore, for protection, note on erosion and sediment control sheets that all devices will be installed as necessary based on the discretion of project personnel. Also, create a legend for installation and removal of BMPs and highlight and date devices as they are installed or removed. It is important that SWPPP plans reflect BMPs that are actually on the ground at any given time and so plan sheets shall be properly updated each time BMP additions and/or removals take place on the project. <br />
<br />
Example erosion and sediment control site plans can be found in [[media:Fig. 806.8.9 2014.docx|Fig. 806.8.9]].<br />
<br />
The engineer shall require modifications to the erosion and sediment controls whenever the:<br />
<br />
:*Design of the construction project has changed in a fashion that could impact the quality of storm water discharges;<br />
:*MoDOT inspections indicate deficiencies in individual BMPs;<br />
:*MDNR/EPA notifies MoDOT of erosion and sediment control deficiencies on site;<br />
:*Erosion and sediment controls are determined to be ineffective in significantly minimizing or controlling erosion and sedimentation;<br />
:*MDNR determines violations of Water Quality Standards have occurred.<br />
<br />
==806.8.10 Site Inspections and Reports==<br />
<br />
The [[:category:105 Control of Work#105.9 Authority and Duties of Resident Engineer (Sec 105.9)|resident engineer]] or inspector is responsible for environmental matters on MoDOT projects. As such, the engineer or inspector shall routinely inspect the condition of erosion and sediment controls and, if allowable due to right-of-way constraints, the receiving streams shall be inspected for off-site sediment deposits for 50 feet downstream of project outfalls. Routine inspections are to be conducted at a frequency of once every 7 calendar days. Additional post-runoff inspections must occur within 48 hours if the runoff event ceases during a normal work day and within 72 hours, on the next business day, if the runoff event ceases during a non-work day such as weekends or state recognized holidays. A runoff event is defined as an event that causes runoff to occur on the job site and could result from rainfall or snow or ice melt. If there are consecutive days of measurable rainfall and/or runoff, these can be considered one event and precipitation totals should be tracked on a daily basis and an event total recorded. Since these consecutive days are considered to be one event, a post-runoff inspection should be done after the rain/runoff ceases; however, general observations should be made daily, especially with regard to outfall BMPs, to ensure BMPs are performing to the desired level. If rainfall or snow/ice melt is not sufficient to cause runoff, inspection reports may not be completed until the next required 7-day inspection. The engineer or inspector will keep a log of all inspections made on the project. Refer to [http://ghepg01/forms/CO/Land%20Disturbance%20Inspection%20Record%20-%20Electronic%20Version.dotx Form 806.8.10, MoDOT Land Disturbance Inspection Record]. <br />
<br />
The engineer or inspector will ensure that rainfall measurements are made for the job site and routinely monitor weather forecasts to recognize when predicted weather may threaten the construction site and when runoff has occurred. If the weather forecasts indicate storms may impact the project site, project personnel should evaluate whether or not the site has adequate BMP protection and is prepared to receive runoff. <br />
<br />
Areas of the project that meet the final stabilization requirements (i.e., 70% permanent vegetative cover over 100% of the area, rock covered, paved, etc.) no longer require inspection, but casual observations should be made to ensure erosion problems do not arise.<br />
<br />
The engineer or inspector shall notify the contractor within 24 hours if any controls are found to be improperly installed, in disrepair, or are not functioning at the desired level of effectiveness. Any deficiencies noted are to be corrected within seven calendar days; however, the engineer and other MODOT inspectors may require immediate attention and issue various directives by other means discussed in [[#806.8.1 Introduction to the Storm Water Permit and Storm Water Polution Prevention Plan (SWPPP)|EPG 806.8.1 Introduction to the Stormwater Permit and SWPPP]]. Directives to the contractor shall be noted in project records, which shall be available for review by DNR upon request. In instances where weather conditions make it impossible to correct deficiencies within 7 days, the engineer or inspector will document site conditions in the inspection reports. This documentation will include a written description and pictures illustrating the adverse conditions. As soon as weather and site conditions become favorable, corrections to deficient BMPs shall be made.<br />
<br />
MoDOT performs environmental compliance training for construction site inspectors, resident engineers, designers and other personnel, including contractors and consultants, to ensure that erosion control inspections are being conducted in a consistent fashion statewide. The individual who performs the training is organizationally located in MoDOT’s Environmental and Historic Preservation Section and does not have supervisory authority over the construction personnel who perform inspections. However, the same individual who performs training has the responsibility of performing statewide audits of construction sites to ensure that SWPPPs are being followed to the extent that off-site contamination does not occur. This individual will usually visit every construction site at least once per year and meet with MoDOT resident engineers, inspectors or contractors to evaluate the land disturbance elements of the project and to ensure consistency of inspections. In cases where deficiencies are identified, the resident engineer or inspector has the responsibility to see that the deficiencies are corrected. <br />
<br />
(Note: There are scenarios associated with the use of borrow and excess (waste) disposal areas, as well as portable plants, when the contractor may be responsible for site inspections. Please refer to [[media:Fig. 806.8.1 2014.docx|Fig. 806.8.1 MoDOT/Contractor Responsibility]] for inspection responsibilities in these scenarios.)<br />
<br />
==806.8.11 Diamond Grinding and Other Surface Treatments==<br />
<br />
Although diamond grinding, grooving, and other pavement surface and bridge deck treatments are not land disturbance activities, the fine material that is removed from the driving surface will become suspended in discharge water and has the potential to contaminate nearby streams if not sufficiently managed. The following shall be considered the minimum requirements for performing this work within the project limits in addition to [http://www.modot.mo.gov/business/standards_and_specs/Sec0622.pdf Sec 622] and [[:Category:622 Pavement and Bridge Surface Removal and Texturing#622.2 Construction Inspection for Diamond Grinding of Existing Portland Cement Concrete Pavement|EPG 622.2.1 Construction Inspection for Diamond Grinding of Existing Portland Cement Concrete Pavement]] .<br />
<br />
The contractor shall submit to the engineer for approval in writing prior to the pre-construction meeting, the best management practices (BMPs) to be used to protect the environment, including the method of disposal whether on right of way or off-site.<br />
<br />
The preferred BMP for slurry management is land application on MoDOT right of way. When slurry is dispersed on the right of way, BMPs shall be installed to keep slurry residue from entering drainage structures, from entering any waterways and from leaving the right of way.<br />
<br />
Prior to starting work, slurry or residue “no discharge zones” will be identified by the engineer with respect to the contractor’s approved BMP and residue disposal plan. Special provisions and restrictions will apply when operating in proximity to streams, wetlands, sensitive species habitat and in karst (landscapes with caves) and groundwater recharge areas.<br />
<br />
The engineer may suspend operations during periods of rainfall or during freezing temperatures.<br />
<br />
==806.8.12 Concrete Washout==<br />
<br />
Concrete washout BMPs should be established in designated areas for all projects where concrete production or delivery is occurring. Inspectors should ensure that concrete washout is not occurring in non-designated areas of the project site. These washouts are used to contain residual concrete, concrete associated liquids and the wash water from cleaning trucks, hoppers and chutes, which typically have a high pH and could contain other chemical additives. Washout BMPs can be non-leaking plastic or bentonite lined pits, a straw bale enclosure lined with plastic, a storage tank or prefabricated BMP or other structure approved by the engineer or inspector. In karst regions of the state, such as the Ozarks, extra care should be taken to ensure proper lining of earthen pits, as cracks and fissures within the bedrock could allow for direct pollution of ground water. Designated washout areas should be located at least 50 feet away from storm drains, ditches, streams or other water bodies. Washouts should be monitored like other BMPs to ensure there are no leaks and that they are operating effectively. They should be cleaned out when they reach 75% of their design capacity. Care should be taken to ensure these structures do not overflow during storm events.<br />
<br />
Upon completion of concrete washout on the project, the engineer or inspector should ensure proper disposal of washout materials. Washout liquids can be allowed to evaporate or be pumped out and properly disposed of. They cannot be discharged into storm drains, ditches, streams or other water bodies. Dried concrete can be broken up and used as clean fill on the project, recycled or properly disposed of by other means.<br />
<br />
==806.8.13 Turbidity Removal and Advanced Treatment Systems==<br />
<br />
Water clarification and the removal of turbidity will usually require the addition of flocculants, polymers, polyacrylamides (PAM), chitosan and other chemicals that cause soil particles to bind together, become heavy and settle to the bottom of a sediment trap or sediment basin.<br />
<br />
Since settling of flocculated soil particles requires very slow moving (still) water, natual and chemical additives should never be introduced into an outfall BMP where water leaves MODOT right of way. In all cases where flocculants are used to reduce turbidity it is essential to include a sediment basin or sediment trap and a ditch liner or ditch check apron that prohibits additional erosion on the downgrade side of the ditch check. <br />
<br />
The following Advanced Treatment Systems are options for use in MODOT projects where turbidity removal is required:<br />
<br />
::* Flocculant logs and flocculant flats that are installed directly in a ditch, pipe or culvert upgrade from a sediment basin or sediment trap.<br />
<br />
::* Flocculant treated ditch checks (i.e. fiber rolls, or compost socks/logs) that have been installed upgrade from a sediment basin or sediment trap.<br />
<br />
::* Flocculant treated rock ditch checks installed upgrade from a sediment basin or sediment trap.<br />
<br />
::* Geo ridge ditch checks with attached flocculant bags, installed upgrade from a sediment basin or sediment trap.<br />
<br />
::* Addition of granular flocculants directly into a ditch, upgrade from a sediment basin or sediment trap.<br />
<br />
::* Erosion control blankets and turf reinforcement mats that have been inoculated with flocculants, and installed upgrade from a sediment basin or sediment trap.<br />
<br />
'''Chemical Stabilizers '''<br />
<br />
Chemical stabilizers, also known as soil binders or soil palliatives, provide temporary soil stabilization. Various products are sprayed onto the surface of exposed soils to hold the soil in place and minimize erosion from runoff and wind. These materials are easily applied to the surface of the soil, can stabilize areas where vegetation cannot be established, and provide immediate protection. <br />
<br />
Use chemical stabilizers alone in areas where other methods of stabilization are not effective because of environmental constraints, or use them in combination with vegetative or perimeter practices to enhance erosion and sediment control. <br />
<br />
Closely follow the manufacturer's recommended application procedures to prevent the products from pooling and creating impervious areas where stormwater cannot infiltrate. <br />
<br />
Inspect chemically stabilized areas regularly for signs of erosion, and if necessary, reapply the stabilizer. <br />
<br />
[[Category:806 Pollution, Erosion and Sediment Control|806.8]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=33229606.2 Guard Cable2014-03-25T18:08:29Z<p>Jonesjb: /* 606.2.7 Construction Inspection Guidelines for Guard Cable */ Clarified policy on 4:1 approved systems.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
{|style="padding: 0.3em; margin-left:1px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes can occur on highways with median widths above MoDOT's initial 60 ft. threshold. Although this width has largely proven to be effective in detering such crashes, no route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history, effectively removing them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed no more than 4 ft. downslope of the edge of the shoulder. With wider shoulders, the downslope location could be less than 4 ft., but in any case, there must be 8 ft. between the barrier and the edge of traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions. <br />
<br />
If the 8 ft. separation cannot be obtained, the designer must work with the Central Office Design Division to assess the potential safety impacts of a decreased deflection distance. If the arrangement cannot be proven reasonably safe, a different barrier system must be used.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' All of the [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use on slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since more than three equivalent sources exist, there is no need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|material certification]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter, unless the system is approved for use on slopes as steep as 1V:4H (4:1). If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter, unless the system is approved for use on slopes as steep as 1V:4H (4:1). No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. <br />
<br />
The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic. Such "double runs" are discouraged, however, since both the initial and lifetime costs are doubled.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=33228606.2 Guard Cable2014-03-25T17:59:08Z<p>Jonesjb: /* 606.2.4.4 Slopes */ Updated information on proprietary systems to more accurately reflect the state of the industry.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
{|style="padding: 0.3em; margin-left:1px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes can occur on highways with median widths above MoDOT's initial 60 ft. threshold. Although this width has largely proven to be effective in detering such crashes, no route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history, effectively removing them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed no more than 4 ft. downslope of the edge of the shoulder. With wider shoulders, the downslope location could be less than 4 ft., but in any case, there must be 8 ft. between the barrier and the edge of traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions. <br />
<br />
If the 8 ft. separation cannot be obtained, the designer must work with the Central Office Design Division to assess the potential safety impacts of a decreased deflection distance. If the arrangement cannot be proven reasonably safe, a different barrier system must be used.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' All of the [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use on slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since more than three equivalent sources exist, there is no need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|material certification]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter. If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter. No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. A steeper side approach slope may allow a passenger vehicle to duck under the guard cable and subsequently not be stopped. The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:128_Conceptual_Studies&diff=33193Category:128 Conceptual Studies2014-03-19T16:36:12Z<p>Jonesjb: /* 128.2 Preventive Maintenance Projects (1R and 2R) */ Clarified intent</p>
<hr />
<div>{| style="padding:0.3em; margin-left:15px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="270px" align="right"<br />
|-<br />
|'''Forms and Figures'''<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/Location%20Study%20Report.dot Location Study Report Format]<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/Conceptual%20Study%20Report.dot Conceptual Study Report Format]<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/3R%20CONCEPTUAL%20STUDY%20REPORT.dot 3R Report]<br />
|-<br />
|[[media:128 3R Design Standards (Rural) 2013.docx|3R - Rural Design Criteria]]<br />
|-<br />
|[[media:128 3R Design Criteria (Urban) Mar 10.doc|3R - Urban Design Criteria]]<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/4R%20PAVEMENT%20REHABILITATION%20ANALYSIS%20DATA%20AND%20CONCEPTUAL%20STUDY%20REPORT.dot 4R Report]<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-Env&Cultural/Request%20for%20Environmental%20Studies.dot RES Form]<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-Env&Cultural/RES%20Instruction%20sheet.doc Instructions for RES Form]<br />
|-<br />
|[[media:127 CE2 Form.doc|CE2 Form]]<br />
|-<br />
|[[media:131.4 Design Exception Info 2013.doc|Design Exception]]<br />
|-<br />
|[[:Category:231 Typical Section Elements for Roadways|Typical Roadway Sections]]<br />
|-<br />
|[[media:128 Straight Line Profile of Exiting Pavement.pdf|Straight Line Profile]]<br />
|-<br />
|[[media:128 Lane Sketch of Existing Pavement and Proposed Lane Additions.pdf|Lane Diagram]]<br />
|}<br />
<br />
A conceptual study is used to coordinate MoDOT thinking on the improvements to be included in a project and to obtain approval of them as required. A conceptual study report is prepared for relatively small projects that provide specific improvements. The approved study is then used as the basis for further design. The format of the study is dependent on the proposed improvements.<br />
<br />
A conceptual study consists of a written report that is presented in one of three formats. The [http://epg.modot.mo.gov/forms/DE-DEForms/Conceptual%20Study%20Report.dot basic format] is used for projects containing geometric improvements. There are also two specialized report formats for projects that primarily consist of improvements to the driving surface and shoulders, with limited geometric improvements. These reports are the [http://epg.modot.mo.gov/forms/DE-DEForms/3R%20CONCEPTUAL%20STUDY%20REPORT.dot 3R conceptual study report] (for resurfacing, restoration or rehabilitation of non-freeway roadways) and the [http://epg.modot.mo.gov/forms/DE-DEForms/4R%20PAVEMENT%20REHABILITATION%20ANALYSIS%20DATA%20AND%20CONCEPTUAL%20STUDY%20REPORT.dot 4R conceptual study report] (for resurfacing, restoration, rehabilitation or reconstruction of interstate or freeway roadways).<br />
<br />
As each project is developed, a conceptual study or a location/environmental study is required to document the direction that the core team is taking to address the identified transportation need. A conceptual study will provide sufficient documentation for the types of projects described below. However, more complex projects or those with a potential for greater environmental impacts will require the preparation of a location/environmental study. The details for preparing a [[:Category:126 Location Study and Alternatives Analysis|Location Study and Alternative Analysis]] are available. In any case, each project that is developed requires the preparation of one of these types of report.<br />
<br />
<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Pavement Rehabilitation Guide'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/Brf02013.pdf Summary 2003]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/RDT02013.pdf Report 2002]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/Brf02013.pdf Summary 2003]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/RDT02013.pdf Report 2002]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
==128.1 Conceptual Study Report==<br />
<br />
The district prepares a conceptual study report, using the necessary format, for the following types of projects:<br />
<br />
:Relatively small projects that provide specific improvements (i.e. signalization, lighting, signing, minor geometric revisions, etc.).<br />
<br />
:Bridge replacement projects on rural low volume roads where it is obvious the only practical new location is at the existing location or adjacent to the existing corridor.<br />
{| style="padding:0.3em; margin-left:15px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="270px" align="right"<br />
|-<br />
|'''CAP-X Worksheet'''<br />
|-<br />
|The [http://tsi.cecs.ucf.edu/index.php/cap-x Capacity Analysis for Planning of Junctions] is a tool that districts can use to consider alternative at-grade intersection types based upon peak flow volumes.<br />
|}<br />
<br />
:Projects environmentally classified as categorical exclusions [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.1 Categorical Exclusion|(CE)]].<br />
<br />
:Projects pending classification as a categorical exclusion (CE2) must have the justification approved by FHWA, which results in a CE determination, prior to preparation of the conceptual study report. A [http://epg.modot.mo.gov/forms/DE-Env&Cultural/Categorial%20Exclusion%20Form.dot CE2 form] is available. (If the CE2 is determined by FHWA to be an [[127.14 National Environmental Policy Act (NEPA) Classification and Documents#127.14.3.2 Environmental Assessment|EA]], a [[:Category:126 Location Study and Alternatives Analysis|Location Study and Alternative Analysis]] is required.)<br />
<br />
For signalization projects, the conceptual study and preliminary signal layout may be combined in one submittal. Likewise, projects that provide preventative maintenance treatments or contracted level course applications to the pavement may only require the preparation of a combined conceptual study and preliminary plans.<br />
<br />
There may be some CE or CE2 projects for which it is advisable to prepare a location study report rather than a conceptual study report. This should be considered in the case of a highly controversial project, or one in which two or more alternatives are being considered that would have different impacts on the community, such as locating an interchange. In this case, for a CE2 project, the [[:Category:126 Location Study and Alternatives Analysis|location study]] is prepared concurrently with the CE2 form to aid in FHWA determination for a CE or an EA classification.<br />
<br />
Approximately 2 months prior to preparing a conceptual study report, the district sends two copies of a written [[127.1 Request for Environmental Services|request for environmental services]] (RES) to Design requesting project screening and early constraint identification. Preliminary screening may have been completed in order to obtain a CE classification from a CE2; however, it is necessary to request more detailed screening to complete the conceptual study report.<br />
<br />
The conceptual study report describes the project purpose and identified need as well as the location and proposed improvements. The conceptual study report identifies the existing and proposed features of the project. It also explains any variations from the originally identified need.<br />
<br />
Most generally a conceptual study report will be used to describe a simple bridge replacement project or other minor road construction project. In a few instances, a project that uses a conceptual study report format will have alternates being considered. In this case, all alternates considered should be documented in the conceptual study report in a manner similar to a location study report.<br />
<br />
Accident data, safety enhancements, access management, how traffic will be handled during construction and the need for construction incentives are all discussed in the report. The accident data is obtained from the [http://tmshome Transportation Management System (TMS)]. The calculation for the [[:Category:128 Conceptual Studies#128.5 Accident Rate Calculation|project accident rate]] is included. The designer carefully analyzes accident data. Any unusual circumstances are noted and recommendations for correction are proposed. Safety enhancements such as guardrail or bridge modification, access management, and the need for bicycle/pedestrian facilities are also discussed.<br />
<br />
The conceptual study report will also discuss the disposition of the existing route. This discussion will document the anticipated disposition of all sections of the existing route in a manner similar to a location study report. A description of the available options for disposition is listed in [[236.14 Change in Route Status Report|EPG 236.14 Change in Route Status Report]].<br />
<br />
All environmental work completed prior to the conceptual study report is summarized and included in the conceptual study report. The conceptual study report then discusses any unusual features or anticipated difficulties to be encountered with the project, such as known [[127.2 Historic Preservation and Cultural Resources|archaeological sites]], [[127.2 Historic Preservation and Cultural Resources|historic bridges]], [[127.4 Wetlands and Streams|wetlands]], [[127.10 Section 4(f) Public Lands#127.10.2.1.1 Section 4(f) Properties|Section 4(f)]] or [[127.10 Section 4(f) Public Lands#127.10.2.1.2 Section 6(f) Properties|Section 6(f)]] lands, [[127.8 Hazardous and Solid Waste|hazardous waste sites]], or other environmental issues as provided by the Design Division.<br />
<br />
The conceptual study report will contain a current estimate of the proposed costs of the improvements for each alternative. Details on the preparation of project estimates can be found in [[104.7 Estimates|EPG 104.7 Estimates]]. Current cost estimates, borrow information when required, and any other pertinent information to the project that is not covered elsewhere are also provided under the remarks section of the report.<br />
<br />
A location sketch, plan sheet drawings, existing and proposed typical sections and other documents as necessary, are attached to show each alternative for the proposed improvement.<br />
<br />
Following the signature of the preparer, a section is included for the recommendations or comments of the district engineer. If necessary to add more detail, the district engineer's comments may be submitted with a separate letter. Following that, signature and date lines are included to indicate the district engineer's approval of the study.<br />
<br />
Preferred design criteria are contained in EPG articles:<br />
:[[230.1 Horizontal Alignment|230.1 Horizontal Alignment]],<br />
:[[230.2 Vertical Alignment|230.2 Vertical Alignment]],<br />
:[[:Category:231 Typical Section Elements for Roadways|231 Typical Section Elements for Roadways]],<br />
:[[:Category:232 Facility Selection|232 Facility Selection]],<br />
:[[:Category:233 At - Grade Intersections|233 At-Grade Intersections]],<br />
:[[:Category:234 Interchanges|234 Interchanges]],<br />
:[[236.13 Designing Right of Way Plans|236.13 Designing for Right of Way]], and<br />
:[[:Category:748 Hydraulics and Drainage|748 Hydraulics and Drainage]].<br />
<br />
Justification for varying from these standards must be submitted on a [[131.1 Design Exception Process|Design Exception Information Form]].<br />
<br />
Approval and submittal of the conceptual study report is detailed in [[:Category:128 Conceptual Studies#128.10 Conceptual Study Report Approval and Submittal|EPG 128.10]].<br />
<br />
==128.2 Preventive Maintenance Projects (1R and 2R)==<br />
<br />
Preventive maintenance projects usually consist of asphalt overlays with little to no additional work, and generally fall into one of two categories:<br />
<br />
*Resurfacing (1R): [[:Category:402 Bituminous Surface Leveling|Contract leveling course (CLC)]]. The contract leveling course program is intended to provide a smooth riding surface for lower volume roadways with existing low-type asphalt surfaces.<br />
<br />
*Resurfacing and restoration (2R): Thin Hot Mix Asphalt Overlay. The highest type alternative available in the pavement preventive maintenance program for flexible pavements. Thin overlays protect the pavement structure, reduce the rate of pavement deterioration, correct surface deficiencies, reduce permeability and improve the ride quality of the pavement. A minor amount of structural enhancement can also be provided with this treatment.<br />
<br />
Although 1R and 2R projects are eligible for federal funding, no conceptual study report is required. However, since there may be no additional DOT activity in the project area for a number of years, the preventive maintenance project core team should audit the corridor for safety deficiencies and document the findings. Isolated deficiencies that present an immediate threat potential should be remedied if the project budget and scope can reasonably accommodate it. The remaining safety enhancements can be deferred and be completed with in-house forces or included in a programmed future project.<br />
<br />
While it is not necessary to design except non-standard items throughout the process, each of them should be documented. The documentation needn't be presented in a formal report, although such a practice is certainly acceptable and is already practiced in a few districts. Irrespective of the form taken by the documentation, it must be sufficient to demonstrate reasonable diligence on the part of the core team in upholding the system wide focus on safety.<br />
<br />
While the following items are the most common areas that bear scrutiny on a preventive maintenance project, the core team will likely identify other concerns not listed here.<br />
<br />
'''Horizontal and Vertical Alignment'''<br />
<br />
In general, the existing alignment is considered acceptable unless there is evidence of site-specific safety problems related to horizontal curvature. The evidence may consist of:<br />
<br />
*Pattern of curve-related crashes<br />
<br />
*Skid marks<br />
<br />
*Scarred trees<br />
<br />
*Substantial edge-rutting<br />
<br />
*Complaints from residents or local police<br />
<br />
*Prevailing speeds 20 mph higher than posted speed <br />
<br />
'''Intersection Sight Distance'''<br />
<br />
In general, the existing intersection sight distance may remain in place unless there is evidence of a site-specific safety problem related to intersection sight distance. Intersection sight triangles should be cleared of obstructions as much as the scope of the project or routine maintenance will allow<br />
<br />
'''Roadside Design'''<br />
<br />
While it is desirable that roadsides are free of fixed objects and non-traversable slopes, the remedial work is only rarely within the scope of 1R and 2R projects. The following items are generally considered deficient and should be noted for future remediation.<br />
<br />
*Fixed objects with 6 ft. of the edge of traveled way.<br />
<br />
*Unshielded areas where the consequences of departure from the roadway are likely to be extremely severe.<br />
<br />
==128.3 Pavement Rehabilitation Projects – Non - Freeway Roadways==<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Pavement Rehabilitation Guide'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/Brf02013.pdf Summary 2003]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/RDT02013.pdf Report 2002]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
The district prepares a [http://epg.modot.mo.gov/forms/DE-DEForms/3R%20CONCEPTUAL%20STUDY%20REPORT.dot 3R Conceptual Study Report] for all Resurfacing, Restoration and Rehabilitation (3R) projects on non-freeway roadways. All 3R projects are designed to certain [[media:128 3R Design Standards (Rural) 2013.docx|design criteria for rural]] and [[media:128 3R Design Criteria (Urban) Mar 10.doc|urban]] highways. These design criteria are '''only''' to be used for 3R projects. The values for urban highways apply to any portion of a 3R project located within the limits of a city or town. Justification for varying from these criteria must be submitted as a [[131.1 Design Exception Process|Design Exception]].<br />
<br />
Approval and submittal of the 3R conceptual study report are detailed in [[:Category:128 Conceptual Studies#128.10 Conceptual Study Report Approval and Submittal|EPG 128.10]].<br />
<br />
===128.3.1 Project Information===<br />
<br />
Any deficiencies, in addition to those included in the originally identified need, that require correction will be explained in the letter of transmittal.<br />
[[image:128.3.2.jpg|right|325px]]<br />
===128.3.2 Traffic Data===<br />
<br />
The designer requests [http://epg.modot.mo.gov/forms/DE-DEForms/3R%20CONCEPTUAL%20STUDY%20REPORT.dot traffic data] from Transportation Planning or the [http://tmshome/TMS/TMS.html TMS] database.<br />
<br />
===128.3.3 Pavement Data===<br />
<br />
Part I of the [http://epg.modot.mo.gov/forms/DE-DEForms/3R%20CONCEPTUAL%20STUDY%20REPORT.dot 3R Conceptual Study Report] shall be submitted to Construction and Materials at an appropriate time that will allow 4 to 6 weeks for a pavement evaluation to be completed and the appropriate pavement solution(s) returned to the district. The Contruction and Materials pavement section will provide the district with practical rehabilition option(s) or the district may recommend a rehabilition option and submit it to the Construction and Materials Division pavement section for approval.<br />
<br />
If the district elects to recommend a rehabilition option to Constrution and Materials pavement section for approval, then the Strategic Highway Research Program manual (publication FHWA-RD-03-031) titled "Distress Identifications Manual for the Long-Term Pavement Performance Project" is used to describe the pavement distress. The pavement distress type and severity is documented. Any drainage issues are also documented. The amount of [[:Category:613 Pavement Repair|pavement repair]] is also estimated and included in the submittal.<br />
<br />
If the distresses are such that the district is considering reconstruction for a given project, then Part I of the [http://epg.modot.mo.gov/forms/DE-DEForms/4R%20PAVEMENT%20REHABILITATION%20ANALYSIS%20DATA%20AND%20CONCEPTUAL%20STUDY%20REPORT.dot 4R Conceptual Study Report] is also submitted to the Constructiion and Materials Division. However, a straight-line profile of the existing pavement for each direction of roadway is not required. The designer should allow 4 to 6 weeks for the evaluation to be completed and recommendations to be returned to the district.<br />
<br />
The requirements of project scoping [[:Category:104 Scope|(EPG 104 Scope)]] cause identification of needs and the development of solutions to occur early in the project development process. Because of the time delay between scoping a project and actual construction, significant changes to pavement condition including accelerated pavement deterioration may occur which can make the original scoped pavement rehabilition strategy inappropriate.<br />
<br />
For these reasons, the original pavement rehabilitation strategy, provided with the 3R report, is reviewed once the construction dollars for the project fall within one or two fiscal years beyond the current year of the STIP. Any significant changes in the pavement condition or other project data will be evaluated. The purpose of this review will be to ensure that the correct rehabilitation strategy is being used to address the pavement deficiency. This re-evaluation is conducted in a time frame that will allow any necessary adjustments to the estimated cost to occur prior to the inclusion of the construction funds in the current year of the STIP.<br />
<br />
Should there be a need to change the recommended strategy, an approval process similar to that for the original 3R report will need to be followed for the revised strategy.<br />
<br />
===128.3.4 Geometric Data===<br />
<br />
The horizontal alignment, vertical alignment, and other features of the highway section are compared to adjoining sections. Any items within the clear zone are listed. A [[131.1 Design Exception Process|design exception]], if necessary, is prepared and submitted for approval that reflects the minimum distance to objects in the clear zone.<br />
<br />
===128.3.5 Accident Data, Safety Enhancements, and Access Management===<br />
<br />
The accident data is obtained from the TMS database. The calculation for the project accident rate is shown in [[:Category:128 Conceptual Studies#128.5 Accident Rate Calculation|EPG 128.5]]. The designer carefully analyzes the accident data. Any unusual circumstances are noted and recommendations for correction are proposed. Safety enhancements such as guardrail or bridge modification, management of access, and the need for bicycle/pedestrian facilities are also discussed.<br />
<br />
===128.3.6 Construction Sequence, Traffic Control, and Construction Incentives===<br />
<br />
The 3R report will contain a discussion of how the construction of the improvement will affect the existing traffic and any recommendations for the construction sequence that will minimize those impacts. A discussion of the traffic control that will be used during construction and the necessity for any construction incentives to shorten the time that normal traffic flow is disrupted is also included in the report.<br />
<br />
===128.3.7 Project Cost Data===<br />
<br />
The 3R report contains a current estimate of the proposed costs of the improvements. Details on the preparation of project estimates can be found in [[:Category:104 Scope|EPG 104 Scope]].<br />
<br />
==128.4 Pavement Rehabilitation Projects for Freeways==<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Pavement Rehabilitation Guide'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/Brf02013.pdf Summary 2003]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri00008/RDT02013.pdf Report 2002]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
The district prepares a [http://epg.modot.mo.gov/forms/DE-DEForms/4R%20PAVEMENT%20REHABILITATION%20ANALYSIS%20DATA%20AND%20CONCEPTUAL%20STUDY%20REPORT.dot 4R Conceptual Study Report] for all resurfacing, restoration, rehabilitation and reconstruction (4R) projects on interstates and freeways. Part I of the 4R Report is also needed for a pavement design thickness determination for any major route in which full depth reconstruction is being consdiered. Part I of the form is completed and submitted to the Construction and Materials Division, with a copy to the Design Division, in order to initiate the pavement rehabilitation analysis or pavement thickness dtermination. <br />
<br />
Construction and Materials will issue a Pavement Type Selection (PTS) letter to the district and provide a copy to Design. Upon receipt of the PTS letter, the district will complete Part II of the form. The district will prepare an estimate of the paving and non-paving costs for each alternate provided in the PTS letter. The completed 4R report (Parts I and II) is submitted to the Design Division, with a copy to the Construction and Materials Division.<br />
<br />
The submittal of the 4R report to the Design Division is accompanied, if necessary, by a request for any [[131.1 Design Exception Process|design exceptions]] that may be required for the project. All 4R projects are designed to current interstate design criteria (since the "4th R" stands for "reconstruction"). These criteria are found in the following EPG locations:<br />
<br />
:[[230.1 Horizontal Alignment]]<br />
<br />
:[[230.2 Vertical Alignment]]<br />
<br />
:[[:Category:231 Typical Section Elements for Roadways|231 Typical Section Elements for Roadways]]<br />
<br />
:[[:Category:232 Facility Selection|232 Facility Selection]]<br />
<br />
:[[:Category:233 At - Grade Intersections|233 At – Grade Intersections]]<br />
<br />
:[[:Category:234 Interchanges|234 Interchanges]]<br />
<br />
:[[236.13 Designing Right of Way Plans|236.13 Designing Right of Way Plans]]<br />
<br />
:[[:Category:748 Hydraulics and Drainage|748 Hydraulics and Drainage (for Bridge and Drainage issues]])<br />
<br />
Justification for varying from these criteria must be submitted as a design exception.<br />
[[image:128.4.jpg|right|200px]]<br />
<br />
All [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|"non-exempt" projects]] require federal oversight and require the approval of the conceptual study report by the FHWA. After review of the information and approval of the requested design exceptions by the State Design Engineer, the Design Division will submit Parts I and II of the 4R report, the rehabilitation analysis, and all costs (paving and non-paving) to FHWA for approval. Upon approval by FHWA, the Design Division will send copies of the approval letter to the district and Construction and Materials by the Design Division along with copies of the approved documents.<br />
<br />
Design exceptions for non-exempt projects will also require approval of FHWA. Once approved by the State Design Engineer, the design liaison engineer will submit all design exceptions to FHWA for approval. After FHWA approval, the Design Division will forward a copy of the approved design exception to the district.<br />
<br />
The requirements of [[:Category:104 Scope|EPG 104 Scope]] cause identification of needs and the development of solutions to occur early in the project development process. Because of the time delay between scoping of a project and actual construction, significant changes to the pavement condition including accelerated pavement deterioration may occur which can make the original scoped pavement rehabilition strategy inapproporiate.<br />
<br />
For these reasons, Construction and Materials is asked to review the original pavement rehabilitation strategy, provided with the 4R report, once the construction dollars for the project fall within one or two fiscal years beyond the current year of the STIP. Any significant changes in project data or pavement condition is also provided. The purpose of this review will be to ensure that the correct rehabilitation strategy is being used to address the pavement deficiency. This re-evaluation is conducted in a time frame that will allow any necessary adjustments to the estimated cost to occur prior to the inclusion of the construction funds in the current year of the STIP.<br />
<br />
Should there be a need to change the recommended strategy, an approval process similar to that for the original 4R report will need to be followed for the revised strategy. This may include re-submission to the FHWA, if applicable<br />
<br />
===128.4.1 Project Information===<br />
<br />
Any deficiencies, in addition to those included in the originally identified need, that require correction are explained in the letter of transmittal.<br />
<br />
===128.4.2 Traffic Data===<br />
<br />
The designer requests [http://epg.modot.mo.gov/forms/DE-DEForms/4R%20PAVEMENT%20REHABILITATION%20ANALYSIS%20DATA%20AND%20CONCEPTUAL%20STUDY%20REPORT.dot traffic data] from Transportation Planning or the TMS database<br />
<br />
===128.4.3 Existing Pavement Data===<br />
<br />
If the district elects to recommend a rehabilition option to Construction and Materials for approval, then the Strategic Highway Research Program manual (publication FHWA-RD-03-031) titled "Distress Identifications Manual for the Long-Term Pavement Performance Project" is used to describe the pavement distress. The pavement distress type and severity is documented. Any drainage issues are also documented. The amount of [[:Category:613 Pavement Repair|pavement repair]] is also estimated and included in the submittal.<br />
<br />
Any items that might restrict the addition of pavement thickness to the existing traveled way are noted. These might include drainage structures, curbing, median barriers, right of way restrictions, or other special conditions.<br />
<br />
The [[media:128 Straight Line Profile of Exiting Pavement.pdf|straight line profile]] identifies the location of all bridges, including overpasses, by log mile and station, and indicates at each location the field measured vertical clearances. It also states if the bridge is to be used in place, rehabilitated or reconstructed. An [[media:128 Lane Sketch of Existing Pavement and Proposed Lane Additions.pdf|example of a sketch]] showing existing lanes, additional lanes proposed under the project, and additional lanes programmed in the future is available. The width of the median and location of existing bridges, including overpasses, is also shown on this sketch. The location of each item is identified by log mile.<br />
<br />
===128.4.4 Proposed Pavement Data===<br />
<br />
The district submits proposed pavement data after the Construction and Materials Division has determined the rehabilitation method. If the district’s proposed pavement rehabilitation method is different than the one recommended by the Construction and Materials Division, justification must be provided.<br />
<br />
===128.4.5 Geometric Data===<br />
<br />
The horizontal alignment, vertical alignment, and other features of the highway section are compared to adjoining sections. Any items within the clear zone are listed. A [[131.1 Design Exception Process|design exception]], if necessary, is prepared and submitted for approval that reflects the minimum distance to objects in the clear zone.<br />
<br />
===128.4.6 Crash Data and Safety Enhancements===<br />
<br />
The crash data is obtained from the TMS database. The calculation for the project crash rate is shown in [[:Category:128 Conceptual Studies#128.5 Accident Rate Calculation|EPG 128.5]]. The crash data included in Part II is used to determine whether a special surface needs to be applied to reduce the accident rate. The designer carefully analyzes the crash data. Any unusual circumstances are noted and recommendations for correction made. Safety enhancements such as guardrail or bridge modification, and the need for bicycle/pedestrian facilities are also discussed.<br />
<br />
===128.4.7 Construction Sequence, Traffic Control, and Construction Incentives===<br />
<br />
The 4R report will contain a discussion of how the construction of the improvement will affect the existing traffic and any recommendations for the construction sequence that will minimize those impacts. A discussion of the traffic control that will be used during construction and the necessity for any construction incentives to shorten the time that normal traffic flow is disrupted is also included in the report.<br />
<br />
===128.4.8 Project Cost Data===<br />
<br />
The 4R report contains a current estimate of the proposed costs of the improvements. Details on the preparation of project estimates can be found in [[:Category:104 Scope|EPG 104 Scope]].<br />
<br />
==128.5 Crash Rate Calculation==<br />
<br />
A crash rate is calculated for each project and included in the conceptual study.<br />
<br />
The formulas for the crash rates are:<br />
<br />
===Segment Crash Rate===<br />
<br />
:<math>\mbox{Segment Crash Rate}=\frac{\mbox{no. of crashes x 100,000,000}}<br />
{\mbox{no. of yrs. x 365 x weighted ave. AADT x length in miles}}</math><br />
<br />
Range lengths of more than one mile should be used in the calculation, if practical. As seen in the rate calculation, an accident rate for a route less than one mile long will result in an artificially high crash rate.<br />
<br />
The segment crash rate yields a result in crashes per hundred million vehicle miles traveled (HMVMT). The number of crashes is the total number of crashes in the study period. For conceptual reports a five-year study period is typically used, utilizing the last five full years of traffic crashes. The AADT and crash data are obtained from the TMS database maintained by Transportation Planning. The calculated crash rate is compared to the five-year average statewide rate for a similar class of highway as obtained from Transportation Planning or found in their Traffic Crash Statistics.<br />
<br />
===Intersection Crash Rate===<br />
<br />
:<math>\mbox{Intersection Crash Rate}=\frac{\mbox{No. of crashes x 1,000,000}}<br />
{\mbox{No. of years x 365 x Entering AADT}}</math><br />
<br />
The intersection crash rate yields a result in crashes per million entering vehicles. Entering AADT includes all legs of the intersection. The number of crashes is the total number of crashes in the study period. For conceptual reports a five-year study period is typically used, utilizing the last five full years of traffic crashes. The AADT and crash data are obtained from the TMS database maintained by Transportation Planning. The calculated crash rate is compared to the five-year average statewide rate for a similar class of highway as obtained from Transportation Planning or found in their Traffic Crash Statistics.<br />
<br />
==128.6 Basic Lighting==<br />
<br />
Basic lighting is provided along the major road at any interchange within the limits of a 3R or 4R project that meets the warrants given in [[:Category:901 Lighting|EPG 901 Lighting]]. If warranted, basic lighting is shown as part of the scope of the project.<br />
<br />
==128.7 Guardrail==<br />
<br />
Criteria for upgrading guardrail are given in [[606.1 Guardrail|EPG 606.1 Guardrail]].<br />
<br />
==128.8 Logical Termini==<br />
<br />
All 3R and 4R projects must have logical termini.<br />
<br />
==128.9 Documentation of Design Exceptions==<br />
<br />
Documentation of [[131.1 Design Exception Process|design exceptions]] is necessary for the department to be able to defend itself from litigation. Litigation may take place many years after the actual construction and permanent documentation is necessary to determine the justification for design exceptions.<br />
<br />
Design exceptions consist of items that vary from published MoDOT design criteria. In most cases the need for design exceptions are the result of the inability to reasonably meet the preferred design criteria specified in this document. However, there are occasions where the improvements will greatly exceed the normal criteria recommended for the type of improvement. These variations must also be documented through the design exception process. When there is doubt if a design exception is required, the design liaison engineer should be consulted.<br />
<br />
The preferred design criteria for new construction on rural and urban highways, 3R and 4R projects are available in various EPG locations:<br />
<br />
:[[230.1 Horizontal Alignment|230.1 Horizontal Alignment]],<br />
:[[230.2 Vertical Alignment|230.2 Vertical Alignment]],<br />
:[[:Category:231 Typical Section Elements for Roadways|231 Typical Section Elements for Roadways]],<br />
:[[:Category:232 Facility Selection|232 Facility Selection]],<br />
:[[:Category:233 At - Grade Intersections|233 At-Grade Intersections]],<br />
:[[:Category:234 Interchanges|234 Interchanges]],<br />
:[[236.13 Designing Right of Way Plans|236.13 Designing for Right of Way]], and<br />
:[[:Category:748 Hydraulics and Drainage|748 Hydraulics and Drainage]].<br />
<br />
The criteria for proper access management can be found in MoDOT’s [[:Category:940 Access Management|Access Management Guidelines]]. On urban projects, turning lane width and whether the pavement is curbed or uncurbed are noted on this form. A Design Exception Information form is not required if all established design criteria are used.<br />
<br />
==128.10 Conceptual Study Report Approval and Submittal==<br />
<br />
The district engineer has the authority to approve all project specific details for projects that meet the requirements to use a conceptual study report, 3R conceptual study report or 4R conceptual study report. For projects requiring a location study/environmental report, the approval and submittal requirements are described in EPG 127. This approval by the district engineer is contingent upon the approval of any design exceptions by the State Design Engineer or approval by the FHWA.<br />
<br />
All [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|"non-exempt" projects]] (interstate, major bridge or certain special projects) require federal oversight and require the additional approval of the conceptual study report by the FHWA. For these projects, the conceptual study report, regardless of the format, and any requested design exceptions are submitted to FHWA.<br />
<br />
The submittal of a [[media:128 4R Conceptual Study Report.doc|4R conceptual report]] to FHWA is a specialized case. All other conceptual study reports are submitted to Design. Design, upon approval of the design exceptions by the State Design Engineer, will send a transmittal letter and necessary information to FHWA for review and approval. Upon receipt of FHWA approval, the Design Division will inform the district to proceed with the design of the project and forward a copy of the approval action and signed design exceptions.<br />
<br />
"Exempt" projects (all other projects) do not require direct federal oversight and will therefore not be submitted to FHWA for approval. The district engineer may approve the conceptual study report, 3R conceptual study report, or 4R conceptual study report for these projects. A copy of these reports is forwarded to Design. For those projects where a [[131.1 Design Exception Process|design exception]] is required the district engineer’s approval is also necessary. The district must submit a copy of the approved design exception to Design. Once the design exception is approved, the district has authority to proceed with the design of the project.<br />
<br />
In both of these situations, the district will provide Design and Construction and Materials a copy of the approved conceptual study report.<br />
<br />
==128.11 [[:Category:122 Aviation|Airports]]==<br />
<br />
If a highway improvement is located within 2 miles (3 km) of an existing [[:Category:122 Aviation|airport]], a letter is submitted to the Design Division as directed in [[:Category:235 Preliminary Plans#235.8 Airports|EPG 235.8 Preliminary Plans]].<br />
<br />
The notice and submittal requirements of Federal Aviation Regulation Part 77 shall be followed if any highway improvement is located near an airport. Notice criteria can be found online at [http://www.faa.gov/airports_airtraffic/airports/regional_guidance/central/construction/part77/#who http://www.faa.gov/airports_airtraffic/airports/regional_guidance/central/construction/part77/#who]. Highway improvements located near airports shall also be coordinated with the Aviation Section in Multimodal Operations. The airspace filings can be submitted electronically through FAA’s website at https://oeaaa.faa.gov/oeaaaEXT/portal.jsp.<br />
<br />
Particular attention is given to all types of signs, light poles, cranes, and large equipment that may require notice as outlined in F.A.R. Part 77. The names and locations of civil and private airports in Missouri can be obtained from the "Missouri Aeronautical Chart" available from the Aviation Section in Multimodal Operations.<br />
<br />
==128.12 SEMA Flood Buyout Program==<br />
<br />
The State Emergency Management Agency (SEMA) has the ability to place permanent deed restrictions on lands located in floodplains. [[127.21 Federal Emergency Management Agency (FEMA) Buyout Properties|These restrictions]] require open space land usage only, no structures, roadways or fills are allowed. If a project encroaches on any deed restricted lands, an official with the city or county must be contacted to identify the exact location of the deed-restricted properties.<br />
<br />
==128.13 Draft Project Scoping Documentation for System Expansion Projects==<br />
<br />
The project manager completes the draft project scoping documentation following approval of the conceptual plan for Major Projects. The details of the documentation are found in [[:Category:104 Scope|EPG 104 Scope]].</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=33040606.1 Guardrail2014-02-11T19:34:47Z<p>Jonesjb: /* 606.1.3.9 Bridge Ends */ Clarified wording</p>
<hr />
<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
<br />
<br />
==606.1.1 Types of Guardrail==<br />
<br />
'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
<br />
'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
<br />
'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
<br />
'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
<br />
==606.1.2 Guardrail Terms==<br />
<br />
'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
<br />
'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
<br />
'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
<br />
'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
<br />
'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
<br />
==606.1.3 Applications==<br />
<br />
===606.1.3.1 3R/4R Projects===<br />
<br />
The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
<br />
* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
<br />
* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
<br />
* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
<br />
* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
<br />
* All existing guardrail not warranted by present standards is to be removed.<br />
<br />
* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
<br />
* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
<br />
:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
<br />
:2. Warranted by an analysis of accident history or,<br />
<br />
:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
<br />
<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
<br />
* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
<br />
* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected or unacceptably connected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
<br />
Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
<br />
On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
<br />
:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
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===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
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Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
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An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
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'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
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'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
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'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.39 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="240px" align="right" <br />
|-<br />
|<center>'''Additional Information'''</center><br />
|-<br />
|align="center"|[[751.1 Preliminary Design#Common Bridge Rails (for Rehabilitations)|Common Bridge Rails (for Rehabilitations)]] Table <br />
|}<br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
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Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an crash history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded or the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
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===606.1.3.10 Bridge Piers and Sign Trusses===<br />
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Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
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===606.1.3.11 Signs===<br />
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Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
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===606.1.3.12 Outer Roadways===<br />
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Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
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===606.1.3.13 Headwalls===<br />
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Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
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When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
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===606.1.3.14 Medians===<br />
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Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
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Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
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[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
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===606.1.3.15 Restricted Lateral Clearance===<br />
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When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
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===606.1.3.16 Barricade of Existing Streets and Roads===<br />
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Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
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===606.1.3.17 Plans===<br />
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Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
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===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
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Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
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===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
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When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
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If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
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==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
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'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
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[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:503_Bridge_Approach_Slabs&diff=32744Category:503 Bridge Approach Slabs2013-12-06T13:43:10Z<p>Jonesjb: /* 503.2 Minor Roads */ Corrected misspelling</p>
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<div>[[image:503 Bridge Approach Slabs.jpg|right|400px]]<br />
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A bridge approach slab is used to provide a smooth and structurally sound transition from the pavement to the bridge. The area between the roadway embankment and the bridge end bent frequently receives inadequate compaction or a different degree of compaction than the roadway fill. Another cause of differential settlement between roadway pavement and the bridge structure is subsidence of compressible original soil layers under the new approach roadway fill's weight, while the bridge is normally founded on more unyielding foundation of solid rock or piling. In order to prevent pavement failure, an unacceptable differential elevation between the pavement and the bridge pavement, and excessive loading on the end bent, a bridge approach slab is constructed to span from the end bent over the roadway embankment.<br />
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Bridge approach slabs are included in the bridge plans prepared by the Bridge Division. Payment for bridge approach slab is included in bridge estimated quantities.<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Bridge Approach Slabs, Performance and Design'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri02033/RDT04010.pdf Report 2004]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri02033/brief.pdf Summary 2004]<br />
|-<br />
|'''Bridge Approach Slabs, Alternative and Cost Efficient Approaches'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/TRyy0915/or11009.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
===503.1 Major Roads===<br />
In site-specific circumstances, the project core team may decide a bridge approach slab is not needed on a [http://wwwi/intranet/tp/documents/MajorHighway2013.pdf major road]. In those cases, a [[131.1 Design Exception Process|design exception]] is required and the minor road guidance, shown below, is followed. When the decision is made to include a bridge approach slab in the project plans, construction personnel will not underrun the item nor will the contractor be allowed to remove it by a [[:Category:130 Value Engineering|Value Engineering]] proposal.<br />
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===503.2 Minor Roads===<br />
Bridge approach slabs, as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/50400.pdf Standard Plan 504.00], are not used on minor roads because of their expense. Bridges on minor roads, with asphaltic pavement, will be constructed without '''any''' bridge approach slabs. In order to maintain an acceptably smooth pavement, maintenance forces may need to fill or patch asphaltic pavement adjacent to the bridge end as settlement occurs.<br />
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Bridges on minor roads with concrete pavement will be constructed with a [http://www.modot.mo.gov/business/standards_and_specs/documents/modified_bridge_approach.pdf modified bridge approach slab] in accordance with the plans. The modified bridge approach slab is considered a roadway item as part of the alternate pavement option.<br />
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This guidance shall be used for new bridge construction or bridge replacement.<br />
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===503.3 Drainage=== <br />
When a bridge approach slab is included in the plans, the roadway items of curb and drain basin as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/60940.pdf Standard Plan 609.40] are also specified. When the bridge approach slab is not needed, a method of moving drainage away from the bridge end will be necessary. In most cases, Type A curb and drain basin will be sufficient. The project core team is to make recommendations for handling drainage as necessary.<br />
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===503.4 Construction Inspection Guidance for [http://www.modot.mo.gov/business/standards_and_specs/Sec0503.pdf Sec 503]===<br />
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'''Material (for Sec 503.2)''' The concrete mix for bridge approach slabs shall be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 501 of the Standard Specifications]. The bridge approach slab shall be constructed of pavement concrete or an approved Class B-1. <br />
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'''Construction Requirements (for Sec 503.3)''' This item is not subject to the Quality Control/Quality Assurance (QC/QA) requirements of [http://www.modot.mo.gov/business/standards_and_specs/Sec0502.pdf Sec 502 of the Standard Specifications]. Particular attention must be given to the grade of the side forms to obtain the desired riding quality. Hand finish methods, as defined by Sec 502.4.8.6, may be used for the bridge approach slab. The bridge approach slab shall be cured and sealed in accordance with [http://www.modot.mo.gov/business/standards_and_specs/Sec0703.pdf Sec 703 of the Standard Specifications] for bridge decks.<br />
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===503.5 Maintenance Activities===<br />
See [[771.1 Mud Jacking Bridge Approach|Mud Jacking Bridge Approach]] for additional information.</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=31921606.1 Guardrail2013-08-21T14:20:23Z<p>Jonesjb: /* 606.1.3.1 3R/4R Projects */ Clarified 3R requirements for upgrading bridge end connections.</p>
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<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
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==606.1.1 Types of Guardrail==<br />
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'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
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'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
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'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
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'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
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==606.1.2 Guardrail Terms==<br />
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'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
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'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
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'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
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'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
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|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
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|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
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|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
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|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
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|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
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|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
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|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
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|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
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|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
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'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
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==606.1.3 Applications==<br />
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===606.1.3.1 3R/4R Projects===<br />
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The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
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* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
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* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
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* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
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* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
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* All existing guardrail not warranted by present standards is to be removed.<br />
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* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
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* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
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:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
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:2. Warranted by an analysis of accident history or,<br />
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:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
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<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
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* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
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* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected or unacceptably connected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
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Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
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On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
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:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
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===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
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Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
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An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
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'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
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'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
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'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.39 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
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Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
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===606.1.3.10 Bridge Piers and Sign Trusses===<br />
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Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
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===606.1.3.11 Signs===<br />
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Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
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===606.1.3.12 Outer Roadways===<br />
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Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
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===606.1.3.13 Headwalls===<br />
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Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
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When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
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===606.1.3.14 Medians===<br />
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Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
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Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
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[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
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===606.1.3.15 Restricted Lateral Clearance===<br />
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When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
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===606.1.3.16 Barricade of Existing Streets and Roads===<br />
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Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
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===606.1.3.17 Plans===<br />
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Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
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===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
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Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
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===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
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When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
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If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
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==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=31801606.1 Guardrail2013-07-24T13:09:22Z<p>Jonesjb: /* 606.1.3.7 Fixed Objects */ Updated Roadside Design Guide figure number</p>
<hr />
<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
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<br />
==606.1.1 Types of Guardrail==<br />
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'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
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'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
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'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
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'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
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==606.1.2 Guardrail Terms==<br />
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'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
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'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
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'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
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'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
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'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
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==606.1.3 Applications==<br />
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===606.1.3.1 3R/4R Projects===<br />
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The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
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* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
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* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
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* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
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* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
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* All existing guardrail not warranted by present standards is to be removed.<br />
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* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
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* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
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:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
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:2. Warranted by an analysis of accident history or,<br />
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:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
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<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
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* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
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* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
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Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
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On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
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:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
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===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
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Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
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An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
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'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
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'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
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'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.39 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
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Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
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===606.1.3.10 Bridge Piers and Sign Trusses===<br />
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Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
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===606.1.3.11 Signs===<br />
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Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
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===606.1.3.12 Outer Roadways===<br />
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Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
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===606.1.3.13 Headwalls===<br />
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Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
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When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
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===606.1.3.14 Medians===<br />
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Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
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Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
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[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
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===606.1.3.15 Restricted Lateral Clearance===<br />
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When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
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===606.1.3.16 Barricade of Existing Streets and Roads===<br />
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Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
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===606.1.3.17 Plans===<br />
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Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
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===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
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Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
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===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
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When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
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If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
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==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
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'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Help_Article&diff=31479Help Article2013-06-13T13:03:48Z<p>Jonesjb: /* Use of Terms in the EPG */ Terms clarified to match the same definitions elsewhere in the EPG.</p>
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|-<br />
|'''Helpful EPG Videos''' <br />
|-<br />
|[[media:Logging into the EPG.wmv|Logging into the EPG]]<br />
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|[[media:Help Finging EPG Info.wmv|Finding Info in the EPG]]<br />
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|[[media:Article History and Receiving.wmv|Article History & How to Receive EMails When Articles are Revised]]<br />
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The Engineering Policy Guide (EPG) contains MoDOT policy, procedure and guidance for the planning, design, construction and maintenance of roadway and related facilities. It also includes specific technical topics of right of way, bridge, traffic and materials. The information is presented in numerous articles having as simple a layout as possible. These articles are numbered to reflect as closely as possible the pay items and divisions from the spec book, ''Missouri Standard Specifications for Highway Construction''.<br />
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|-<br />
|'''EPG articles are not referenced as "sections" but as EPG XXX.X or "articles" to avoid confusion with MoDOT specs.'''<br />
|}<br />
The EPG is not a contract document and EPG articles are referenced as EPG XXX.X or "articles" - not "sections" - to avoid confusion with MoDOT specs. Where a conflict exists between the EPG and a contract, the contract document rules. References and links to the ''Missouri Standard Specifications'' are given as "Sec XXX.XX" or "Section XXX.XX of the Standard Specifications." References and links to the ''Missouri Standard Plans for Highway Construction'' are "Standard Plan XXX.XX". <br />
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===Organization===<br />
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Articles are grouped into the spec book’s divisions (for example, the EPG articles in [[:Category:100 GENERAL|EPG 100 General]] mirror Division 100 specs, articles in [[:Category:300 BASES|EPG 300 Bases]] mirror Division 300 specs, etc.). Many articles have been subdivided into additional articles. For example, the reader may notice that [[903.6 Warning Signs|EPG 903.6 Warning Signs]] and other EPG 903 articles are listed at the bottom of [[:Category:903 Highway Signing|EPG 903 Highway Signing]]. <br />
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In most articles the reader will notice numerous words in <font color=#0033ff>blue</font color>. These words are links to another article, figure or website with related information. This allows the reader to effectively navigate.<br />
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While every effort has been made to base the article numbers on MoDOT pay items and specs, not all articles in the EPG are reflected in the pay items and specs. For example, many EPG “100 General” articles are important to the design and construction of roadway facilities but do not directly correspond to specific pay items. Some of these are:<br />
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* [[:category:121 Project Planning, Prioritization and STIP Commitments|EPG 121 Project Planning, Prioritization and STIP Commitments]]<br />
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* [[:Category:127 MoDOT and the Environment|EPG 127 MoDOT and the Environment]]<br />
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* [[:Category:130 Value Engineering|EPG 130 Value Engineering]]<br />
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* [[:Category:132 Safety|EPG 132 Safety]]<br />
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* [[:Category:133 Snow and Ice Control|EPG 133 Snow and Ice Control]]<br />
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Similar examples are to be found in the EPG 200, EPG 300, etc. articles.<br />
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===[[media:Help Finging EPG Info.wmv|Searching the EPG]]===<br />
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'''Google.''' Although this document has been organized in a logical manner (at least to the writers), it does contain a huge amount of information that can make finding a specific idea difficult. Therefore, a Google search engine is available on the left near the top of every article. It functions in the same manner as a conventional search engine on the worldwide web and is very effective!<br />
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'''Find (on This Page).''' Once the reader has used the Google search engine to arrive at an article, it may still be difficult to find the reference’s exact location since some EPG articles are large. In the upper left of each EPG article, next to “File”, we recommend the reader click “Edit”, then, in the drop-down menu, “Find (on This Page)” and type in the desired key word(s). The hot key for "Find (on This Page)" is "Ctrl-F". If the entry is in the article, it will be highlighted.<br />
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===How best to view the articles===<br />
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The articles are best viewed on your computer monitor with the following settings:<br />
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<center>''Click on any picture to view''</center><br />
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{|align="center"<br />
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|'''17-in. Monitors:'''||[[Image:Help Section Screen Resolution.GIF|175px|thumb|<center>'''1024 x 768 pixels screen area'''</center>]]||[[Image:Help Section Text Size.gif|175px|thumb|<center>'''Medium text size in wiki "View" settings'''</center>]]|| ||<br />
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|'''Wide Screen Monitors:'''||[[image:Help, Resolution Wide Screen.jpg|180px|thumb|<center>'''1680 x 1050 pixels screen area'''</center>]]||[[image:Help, Text Size Wide Screen.jpg|180px|thumb|<center>'''Medium text size'''</center>]]||[[image:Help, EPG Text Size Wide Screen.jpg|180px|thumb|<center>'''Larger text size in wiki "View" settings'''</center>]]<br />
||[[image:Help, View Zoom.jpg|180px|thumb|<Center>'''125% zoom in wiki "View" settings'''</center>]]<br />
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===Use of Terms in the EPG===<br />
:'''Shall''' and '''Will''' indicate a required, mandatory, or specifically prohibitive practice. Shall and will statements shall not be modified or compromised based on engineering judgment or engineering study.<br />
:'''Should''' indicates a recommended, but not mandatory, practice in typical situations. Deviations are allowed if [[:Category:900 TRAFFIC CONTROL#Engineering Judgment|engineering judgment]] or [[:Category:900 TRAFFIC CONTROL#Engineering Study|engineering study]] indicates the deviation to be appropriate.<br />
:'''May''' indicates a permitted practice and carries no requirement or recommendation.<br />
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===EPG Approval Process===<br />
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|style="background:#99ffff"|<center>'''On behalf of my division, I am to propose a textual revision that clarifies (that is, does not greatly change policy) an EPG article. What do I do?'''</center><br />
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|Just copy and paste the affected portion of your division's EPG article into a Word file. Place the Word file into revision mode and make your proposed changes to the file. <br />
|-<br />
|Then email the Word file, along with any other necessary information (such as the fiscal impact, why your division wants the change, etc.) to the Engineering Policy Group. <br />
|-<br />
|If your division’s info is already in the EPG, do not email Word files of revisions to your division’s old manual. Base your division's proposed revisions on EPG text, not the old manuals.<br />
|-<br />
|style="background:#99ffff"|<center>'''On behalf of my division, I am to propose an EPG revision that changes policy in an EPG article or affects more than one division or the districts. What do I do?'''</center><br />
|-<br />
|Along with the actual proposed textual revision of the EPG, provide:<br />
|-<br />
| 1) Any other standard affected by the revision,<br />
|-<br />
| 2) The name of the proposal's sponsor,<br />
|-<br />
| 3) The proposal's summary and <br />
|-<br />
| 4) The proposal's fiscal impact.<br />
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Revisions are provided to the Chief Engineer and the Senior Management Team on a bimonthly schedule via electronic ballot. Each District Engineer and Division Engineer has the opportunity to comment on revisions to their respective Director. The Program Delivery and System Management Directors submit the final decision on Level 2 revisions to the Engineering Policy Administrator.<br />
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Proposed EPG revisions can also be submitted to the Engineering Policy Group from a division. The proposal must reflect information approved by the division head. Proposed revisions will be submitted for approval.<br />
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Every submittal must also document, along with the actual proposed textual revision to the EPG:<br />
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:'''1) Any other standard affected by the revision.''' Provide electronic files of all the revisions to other MoDOT standards (Standard Plans, specs, JSPs, etc.) impacted by the proposal. Word files in revision mode are required for textual changes. Dgn files are preferred for Standard Plan revisions although a redlined hard copy showing the proposed changes is also acceptable.<br />
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:'''2) Sponsor.''' The name of the sponsor from within the division proposing the revision is required. The sponsor is the person most knowledgeable or central to the proposal.<br />
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:'''3) Summary.''' Provide the reason why the idea should be carried out (why it is necessary or its benefit). This justification may be critical in the decision to approve the proposal or not.<br />
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:'''4) Fiscal Impact.''' Provide a dollar estimate for the proposal’s costs or savings to MoDOT. Include whatever calculations (initial savings or life cycle savings, for example) or assertions are necessary to accurately convey the proposal’s financial impact. The fiscal impact must be a numeric dollar value, not simply a vague financial discussion.<br />
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Proposed revisions will be categorized by the Engineering Policy Administrator based on the following guidelines:<br />
<div id="Level 1 Approval"></div><br />
'''Level 1 Approval.''' If the idea is a routine technical matter, an errata correction or a clarification, it can be approved by the Engineering Policy Administrator without comment from the district engineers, the division engineers or the Chief Engineer. The EPG will be revised as necessary. <br />
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'''Level 2 Approval.''' If the idea is a moderate technical change, if it requires specific expertise (e.g. structural design, etc.) or if it impacts more than one division then it will be reviewed by the district and division engineers. They will provide their comments to the appropriate Director(s) who will consider the idea before providing their decision to the Engineering Policy Administrator. The Federal Highway Administration will also be given 20 working days to provide comment to the Engineering Policy Administrator. The EPG will be revised as necessary. <br />
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'''Level 3 Approval.''' If the idea is a complex technical change, contentious, has high cost or impacts MoDOT's external conduct of business it goes directly to the Chief Engineer after initial review and comment. The EPG will be revised to reflect the Chief Engineer's decision. The Federal Highway Administration requires 20 working days to provide comment to the Engineering Policy Administrator on any proposed EPG revision. <br />
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In order to speed the approval process, district and division engineers should have at least one alternate team member with full authority to act when they are absent. This will avoid the districts' and divisions' forfeiting their right to comment.<br />
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|align="center"|'''Tips on Text'''<br />
|-<br />
|While the Engineering Policy Group edits all submittals, a few grammatical guidelines for the EPG include:<br />
|-<br />
|'''Assure/Ensure/Insure:''' The word “assure” is a personal guarantee based on reputation. “Ensure” is used when the party is to make certain of something or to be careful. “Insure” refers to actions protected by insurance, and indicates that money is involved.<br />
|-<br />
|'''Dimensions:''' Typically use “high”, “wide” and “long” instead of “in height”, “in width” and “in length”.<br />
|-<br />
|'''Farther/Further:''' Use “farther” to express a physical distance, such as 10 miles farther, and “further” for a non-physical dimension, such as further thought.<br />
|-<br />
|'''Fewer/less:''' Use “few” or “fewer” for something comprised of a small number of countable components (such as fewer dollars, fewer gallons of water, etc.). Use “less” for amounts that are not being counted (less money, less water, etc.).<br />
|-<br />
|'''Gage/Gauge:''' Gage is the size or thickness. Gauge is the instrument for measuring.<br />
|-<br />
|'''Gender:''' Minimize the use of “he/she”, “he and she” and “she or he”.<br />
|-<br />
|'''High/Tall:''' Use “high” to express a lofty position, such as the clouds are high. Use “tall” to express a great vertical dimension, such as the tall post.<br />
|-<br />
|Also refer to [[Help:Contents#Use of Terms in the EPG|Use of Terms in the EPG]], above.<br />
|}<br />
Once a substantive Level 2 or 3 revision is approved, a notice (with effective date if required) will be posted on the EPG Main Page under the heading “Recent Changes”. <br />
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The Engineering Policy Group also receives proposed EPG corrections or improvements from districts, although most significant technical revisions would normally go through the divisions. We will gladly receive emails with your specific correction.<br />
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====EPG Ballot Cycles====<br />
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!style="background:#99ffff"| ||style="background:#99ffff"|Deadline for Revision Proposal to Engineering Policy Group||style="background:#99ffff"|Approved Revisions Available for Use but not Effective||style="background:#99ffff"|Revisions become Effective for all Subsequent Lettings<br />
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|style="background:#FFFFFF" width=90|'''Cycle 1'''||style="background:#FFFFFF"| 1-Jan||style="background:#FFFFFF"| 1st week of Feb ||style="background:#FFFFFF"|1-Apr<br />
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|'''Cycle 2'''|| 1-Mar|| 1st week of Apr ||1-Jun<br />
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|style="background:#FFFFFF"|'''Cycle 3'''||style="background:#FFFFFF"| 1-May|| style="background:#FFFFFF"|1st week of Jun ||style="background:#FFFFFF"|1-Aug<br />
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|'''Cycle 4'''|| 1-Jul|| 1st week of Aug ||1-Oct<br />
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|style="background:#FFFFFF"|'''Cycle 5'''||style="background:#FFFFFF"| 1-Sep||style="background:#FFFFFF"| 1st week of Oct ||style="background:#FFFFFF"|1-Dec<br />
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|'''Cycle 6'''|| 1-Nov|| 1st week of Dec ||1-Feb<br />
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<br />
====Style Guide for Submitting Proposed EPG Revisions====<br />
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When a division proposes a revision to the Engineering Policy Guide (EPG), what should be submitted to the Engineering Policy Group?<br />
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The division should usually begin by referencing the current contents of the EPG article to be revised. Submit a Word document in revision mode showing both proposed additions and deletions to the EPG article. The proposed revision should use complete sentences and paragraphs as much as possible. Bullets are permissible, but they are typically used sparingly. <br />
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If changes are proposed to EPG figures, provide the new .jpg files for photos and .pdf or MicroSoft Word documents for the textual figures. The EPG wiki can accommodate a number of other types of files, but .jpg, .pdf and .doc files tend to be most efficient.<br />
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===[[media:Logging into the EPG.wmv|Logging into the EPG]]===<br />
[[image:Help Article EPG Login.jpg|550px|right]]<br />
Just viewing the EPG, without logging into it, opens the single reference for all MoDOT engineering and engineering-related guidance. But logging into the EPG permits the reader access to a number of capabilities including viewing the history of an article, leaving comments on a discussion page, tracking revisions through "my watchlist", accessing a printable version of an EPG article and viewing the "what links here" (that shows all the other articles linked to the chosen article).<br />
[[image:Help Article Log in.jpg|right|125px]]<br />
To log in to the EPG, MoDOT employees simply click the "Log in" (located at the top of any EPG article). The "Username" required by the EPG is the same as the username entered when logging into a MoDOT computer. The "password" required by the EPG is also the same as your computer password. Yes, every time your computer's password changes, so will your EPG password. <br />
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====Benefits of Logging into the EPG==== <br />
Your engineering and engineering-related information is already incorporated into the EPG, but logging into the EPG will make this information handier and more useful.<br />
[[image:Help Article history.jpg|right|175px]]<br />
=====History=====<br />
Would it be useful for you to be able to find when and how an article that you are interested in changed? Or view exactly what an EPG article stated and how it looked in the past? Log into the EPG and a “History” tab is available at the top of every article, providing a view of any previous versions of the EPG article or comparing any two versions of the article on a line-by-line basis.<br />
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Many of the revisions will have a brief explanation. A bold “m” indicates a minor change (either a [[Help Article#Level 1 Approval|Level 1 Approval]] or editorial change).<br />
[[image:Help Article watch.jpg|right|375px]]<br />
=====Watch and My Watchlist=====<br />
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Would you find it useful to easily gather the articles in which you are interested and also be able to view the changes to these articles?<br />
<br />
Log into the EPG and a “watch” tab is located at the top of every article in the EPG. By simply clicking the “watch” tab (and causing it to become “unwatch”), the article is added to your watchlist (those articles of which you want to keep track). <br />
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How are the revisions to your watchlist articles viewed? At any time you may open “my watchlist”, located above the EPG article’s tabs, and choose whether you want to view the changes to your selected articles that occurred during the past hour, 2 hours, 6 hours, 12 hours, day, 3 days, 7 days or all the changes that have occurred. Minor changes to a “My watchlist” article are identified with a bolded “m”. New articles are identified with an “N”. A brief description is provided for notable revisions.<br />
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=====My Preferences=====<br />
Would you find it useful to have an email inform you every time an EPG article of interest to you has been changed? <br />
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This email would not provide the details of the revision, but that the article was revised in some manner. Log in to the EPG and you will be able to check the article’s history to view the actual revision.<br />
[[image:Help Article my preference.jpg|right|375px]]<br />
To obtain an email alert every time an EPG article of interest has been revised, click “My Preferences”, located above the EPG article’s tabs. This leads to a “User Profile” tab. Near the bottom of the “User Profile” is the “E-mail” portion in which you may choose the various revision situations to send you an email.<br />
<br />
=====Discussions and Suggestions =====<br />
Those logged into the EPG are encouraged to use the discussion capability of the EPG. If you have a question, it is likely others may, too. Any suggestions you have may also be very helpful to another reader, as well. Use the “Discussion” capabilities of the EPG to contribute questions and suggestions for all other readers. The Engineering Policy staff monitors all articles so that your comment can be addressed. <br />
[[image:benefit discussion.jpg|left|275px]]<br />
After logging in, simply go to the article of concern and select the “Discussion” tab at the top of the article. If your comment or question is the first discussion for the article, you will be shown an edit screen. Type in your comment or question. Otherwise, an existing discussion will be shown. Additional comments can be added by selecting the “+” tab.<br />
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====Division Contacts====<br />
Since the divisions provide authoritative input, consulting with their liaisons or contacts may provide the help you require or receive your input. Below is a listing of divisional personnel with whom the Engineering Policy staff works and who may be helpful to you:<br />
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::'''''Bridge:''''' Greg Sanders<br />
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::'''''Chief Counsel's Office:'''''<br />
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::'''''Construction and Materials'''''<br />
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:::Chemical Laboratory: Todd Bennett, Leonard Vader<br />
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:::Construction Engineering: Jeremy Kampeter <br />
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:::Geotechnical Engineering: Mike Fritz<br />
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:::Materials: <br />
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:::Physical Laboratory: Victoria Woods<br />
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::'''''Design:''''' <br />
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:::Environmental & Historic Preservation: Mike Meinkoth<br />
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:::Right of Way: <br />
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::'''''Maintenance:''''' Tim Jackson<br />
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::'''''Motor Carrier:''''' Jan Skouby<br />
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::'''''Multimodal:''''' Michelle Teel<br />
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::'''''Planning:''''' Renate Wilkinson, Jenni Jones, Machelle Watkins<br />
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::'''''Traffic:''''' Julie Stotlemeyer</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:645_Mailbox_Turnouts_and_Supports&diff=30951Category:645 Mailbox Turnouts and Supports2013-03-19T19:53:49Z<p>Jonesjb: Added a link to Standard Plan 203.35 for added convenience.</p>
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|- <br />
|'''Figures'''<br />
|-<br />
|[[Media:645 Mailbox Assembly Standards.pdf|Mailbox Assembly Examples]]<br />
|-<br />
|[[Media:645 Sample Mailbox letters.doc|Sample Letters to Postmaster]]<br />
|}<br />
<br />
Mailboxes and their support posts shall be located so as not to interfere with normal maintenance operations. Shoulders narrower than 8 ft. require special mailbox turnouts in accordance with [http://www.modot.org/business/standards_and_specs/documents/20335.pdf Standard Plan 203.35]. For shoulders wider than 8 ft., special mailbox turnouts are not necessary. <br />
<br />
The post office has established safety requirements, specifications, rules and recommendations for the erection and maintenance of mailboxes. Examples of [[Media:645 Mailbox Assembly Standards.pdf|acceptable mailbox assemblies]] are available. Individual mailboxes that interfere with maintenance operations or are considered an obstruction should be requested to comply with the post office standards. The local postmaster should be contacted before any action is taken regarding mailbox assemblies that are considered an obstruction.<br />
[[image:645.jpg|left|300px]]<br />
The maximum strength support for erecting mailboxes on a highway is a nominal 4 in. x 4 in. square or 4 1/2 in. diameter wood post or a 1 1/2 in. to 2 in. standard steel or aluminum pipe post. The post is embedded a maximum of 24 in. into the ground. <br />
<br />
Mailbox turnouts may be provided on resurfacing projects that include some earthwork, such as [[:Category:215 Shaping Slopes|shaping slopes]]. Consideration is given to inclusion of this item where the finished shoulders are not of sufficient width to allow a vehicle to get completely off the travelway.<br />
<br />
When a stabilized shoulder is not provided, the turnout is constructed with 4 in. of Type 1 or 2 aggregate with a 2 in. plant mix bituminous pavement surfacing.<br />
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Use pipe only when required by restrictive right of way or extreme drainage condition.<br />
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During the design stage of the project, any mailbox support that does not meet these criteria is noted by location. A [[Media:645 Sample Mailbox letters.doc|written notice]] is sent to the local postmaster identifying these locations and requesting their assistance in requiring the mail patron to change the mailbox support to comply with these criteria. This will reduce the potential safety hazard along the roadway that results from the use of non-complying mailbox supports. The design file will document that these mailboxes were checked and the action taken through the local postmaster. The District Construction and Materials Engineer is furnished copies of necessary correspondence for use after award of the contract.<br />
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'''Maintenance Responsibility'''<br />
<br />
MoDOT is responsible for the maintenance of mailbox turnouts and these turnouts should be surfaced with suitable material as necessary.</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=30377606.2 Guard Cable2012-12-18T12:28:15Z<p>Jonesjb: /* 606.2.3 Warrants */ Clarified the effect of median width on cable warrants</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
{|style="padding: 0.3em; margin-left:1px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes can occur on highways with median widths above MoDOT's initial 60 ft. threshold. Although this width has largely proven to be effective in detering such crashes, no route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history, effectively removing them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed no more than 4 ft. downslope of the edge of the shoulder. With wider shoulders, the downslope location could be less than 4 ft., but in any case, there must be 8 ft. between the barrier and the edge of traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions. <br />
<br />
If the 8 ft. separation cannot be obtained, the designer must work with the Central Office Design Division to assess the potential safety impacts of a decreased deflection distance. If the arrangement cannot be proven reasonably safe, a different barrier system must be used.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' Three [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use one slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since three equivalent sources exist, there is not need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|public interest finding]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter. If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter. No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. A steeper side approach slope may allow a passenger vehicle to duck under the guard cable and subsequently not be stopped. The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:450_Bituminous_Pavement_Design&diff=30255Category:450 Bituminous Pavement Design2012-11-20T13:56:16Z<p>Jonesjb: /* 450.9 Safety EdgeSM */ Clarified the intent of Safety Edge on paved shoulders.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right" <br />
|- <br />
|'''Figures'''<br />
|-<br />
|[[Media:450 Estimate Factors.pdf| Estimate Factors]]<br />
|}<br />
<br />
==450.1 Asphalt Binder==<br />
<br />
Performance grade (PG) asphalt binders are identified by their desired "high temperature" (e.g. "64", "70", "76", etc.) and "low temperature" (e.g. "-22", "-28", "-34", etc.) characteristics. The temperature numbers represent Celsius degrees and are used in 6 degree increments. The high temperature value is associated with controlling rutting, while the low temperature value is associated with resisting cold weather cracking. The following table should be used as a guide to select asphalt binder grades for bituminous mixtures. <br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ '''Asphalt Binder Selection Criteria'''<br />
! style="background:#BEBEBE"|Type of Corridor !! style="background:#BEBEBE"|Traffic Level !! style="background:#BEBEBE"|Type of Mix !! style="background:#BEBEBE"|Asphalt Binder<br />
|-<br />
|rowspan="2"|Interstates and Other Freeways<br />
|rowspan="2"|All Levels<br />
|Surface Mixture (SP125 or SMA) and First Underlying Lift<br />
|PG 76-22<br />
|-<br />
|Remaining Underlying Lifts<br />
|PG 64-22<br />
|-<br />
|rowspan="4"|Other Remaining Major Routes<br />
|rowspan="2"|Heavy Volume<br />
|Surface Mixture (SP125) and First Underlying Lift<br />
|PG 70-22<br />
|-<br />
|Remaining Underlying Lifts<br />
|PG 64-22<br />
|-<br />
|rowspan="2"|Medium or Low Volume<br />
|Surface Mixture (SP125 or BP)*<br />
|PG 64-22<br />
|-<br />
|Underlying Lifts<br />
|PG 64-22<br />
|-<br />
|Minor Routes<br />
|All Levels<br />
|All Mixtures (Generally BP-1 as Surface Mix)<br />
|PG 64-22<br />
|-<br />
|colspan="4" style="background:#99CC99"|*Note: Requires JSP to include appropriate smoothness requirements.<br />
|}<br />
<br />
The low temperature number is to remain as indicated in the above table. The high temperature numbers have been set for the traffic loads and operation speeds normally associated with these corridors. The high temperature numbers are recommended minimums and are not to be reduced; however, may be raised to a PG 70-22 or PG 76-2, when deemed necessary, to accommodate actual or anticipated traffic conditions. Typically, the high temperature number should be raised one increment (6 degrees) when traffic speeds are expected to be in the range of 12 to 45 mph and raised two increments (12 degrees) for extremely slow traffic of < 12 mph. Typical candidates for these high temperature number raises are roadways with AADT greater than 3500 that are in a highly congested, urbanized area, have frequent stop and go traffic, or have steep grades with significantly slow traffic speeds. Use of any other PG asphalt binder must be approved by the State Construction and Materials Engineer.<br />
<br />
If a higher type PG asphalt binder is warranted, it shall be used in the surface mixture and the first lift of the underlying mixture.<br />
<br />
==450.2 Mix Selection==<br />
<br />
The following table should be used as a guide in selecting the appropriate asphalt mix. See [[Other Aspects of Pavement Design#Thickness Determination|Thickness Determination]] for additional mix selection discussion regarding minor road spot improvements.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
! style="background:#BEBEBE"|Corridor Designation !! style="background:#BEBEBE"|Traffic !!! style="background:#BEBEBE"|Recommended Mix <br />
|-<br />
|Interstates and Other Freeways|| All Traffic || Superpave<br />
|-<br />
|Remaining Major Routes|| Total Average 24 Hour Commercial Truck Traffic <math>\approx</math> 600 or greater || Superpave<br />
|-<br />
|Remaining Major Routes|| Total Average 24 Hour Commercial Truck Traffic <math>\approx</math> less than 600 ||| BP-1 (Sec 401)<sup>(1)(2)</sup><br />
|-<br />
|Minor Routes|| Total Average 24 Hour Commercial Truck Traffic <math>\approx</math> 600 or greater || Superpave<sup>(2)</sup><br />
|-<br />
|Minor Routes|| AADT > 3500 and Total Average 24 Hour Commercial Truck Traffic < 600 ||| BP-1 (Sec 401) <br />
|-<br />
||Minor Routes|| AADT < 3500 and Total Average 24 Hour Commercial Truck Traffic < 600 ||| BP-1 or BP-2<sup>(3)</sup><br />
|-<br />
|colspan="3" style="background:#99CC99"|<sup>(1)</sup>Note: Requires JSP to include appropriate smoothness requirements.<br />
|-<br />
|colspan="3" style="background:#99CC99"|<sup>(2)</sup>Note: Consideration should be given to alter mix type for overlays based upon existing conditions.<br />
|-<br />
|colspan="3" style="background:#99CC99"|<sup>(3)</sup>Note: The selection of which mix to use is left to the district's discretion based upon past field performance.<br />
|}<br />
<br />
==450.3 Layer Design==<br />
'''Minimum Lift Thickness'''<br />
<br />
The minimum lift thicknesses for asphalt layers should be:<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
! style="background:#BEBEBE"| SP250 !! style="background:#BEBEBE"| SP190 !! style="background:#BEBEBE"| SP125 !! style="background:#BEBEBE"| SP95 and BP-2 !! style="background:#BEBEBE"| BP-1 !! style="background:#BEBEBE"| PMBB<br />
|-<br />
|align="center"| 3 in. ||align="center"| 2¼ in. ||align="center"| 1¾ in. ||align="center"| 1½ in. ||align="center"| 1¾ in. ||align="center"| 3 in. <br />
|}<br />
<br />
==450.4 Level Course==<br />
<br />
Existing surfaces, both asphaltic and portland cement concrete, should be prepared either by milling or leveling course before the first full-thickness lift of asphalt is placed. Milling is the preferred method of leveling, however PMBP or SP125 asphaltic concrete may be used for spot wedging and for leveling course as per the standard specifications, providing the minimum thickness is not less than the following:<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
! style="background:#BEBEBE"| BP-1 and SP125 !! style="background:#BEBEBE"| BP-2 and SP95 !! style="background:#BEBEBE"| BP-3 <br />
|-<br />
| 1 in. || ¾ in. || ½ in. <br />
|}<br />
<br />
The level course can be one design level lower than the lift above it. For example, an SP level C design may be used to level under an SP level B overlay. A BP mix may be used to level under an SP Level C overlay.<br />
<br />
==450.5 Payment==<br />
<br />
Payment for asphaltic concrete by the square yard should only be used for full depth asphaltic concrete pavements on alternate bid projects. All other payment for asphaltic concrete should be by the ton. For preliminary design, [[Media:450 Estimate Factors.pdf|estimate factors]] may be used to compute quantities for bases, flexible type pavements, seal coats, etc. For final design, the designer should request estimate factors for anticipated rock formations from the District Construction and Materials Engineer to obtain more reliable results. When payment is by the ton, estimate factors should be shown on the plans with a note "For Information Purposes Only." When payment is by the square yard, estimate factors should not be shown on the plans.<br />
<br />
==450.6 Automatic Screed Control or Established Grade Reference==<br />
<br />
The standard specifications require the use of automatic screed controls with the sensor following a traveling reference plane. In some instances, such as a badly warped pavement or very poor riding condition, the use of an established grade reference may be desirable. If the established grade reference is desired, a special provision must be included in the contract requiring its use for the initial pass of the paver when placing the first continuous layer. The special provision may be modified to require the established grade reference for a portion of a project if necessary.<br />
<br />
==450.7 Commercial Mixtures==<br />
<br />
The standard specifications permit the use of approved commercial mixture for plant mix bituminous pavement and plant mix bituminous base course when so specified in the contract.<br />
Commercial mixtures are not permitted where Section 403 or Superpave mixtures are specified. Care should be exercised when setting up small quantities of asphaltic concrete in that it may be more desirable, all factors considered, to use plant mix bituminous pavement so that a commercial mixture can be permitted.<br />
<br />
==450.8 Asphalt Over Rubblized Pavement==<br />
[[Image:Asphalt Over Rubblized Pavement.jpg|right]]<br />
Rubblization is the in-place breaking of an existing Portland Cement Concrete (PCC) pavement into an aggregate base for new hot mix asphalt. When major asphalt rehabilitation over existing concrete pavement is considered the existing pavement is rubblized prior to the asphalt overlay. If the existing pavement consists of asphalt over concrete the existing asphalt should be removed prior to rubblization.<br />
<br />
When rubblization is used, the asphalt is paid for by the ton of mix necessary to obtain the thickness indicated by Construction and Materials. The plan quantity should be established with consideration for thickness in excess of that specified to account for irregularities in the existing pavement. Similar to unbonded overlay the contractor is required to establish the existing roadway profile and set the final overlay profile. For this reason the bid item for contractor staking should be included in the contract.<br />
<br />
There must be adequate subgrade support under old rigid pavements. Dynamic cone penetrometer (DCP) testing of the unbound layers under the PCC pavement, performed during the condition surveys, must indicate that adequate support exists for rubblization to occur.<br />
<br />
==450.9 Safety Edge<sup>SM</sup>==<br />
<br />
Shaping the edge of pavement to a 30-degree bevel is an effective strategy for mitigating the negative effects associated with vertical edge drop-off. <br />
<br />
As with conventional paving, the graded material adjacent to the Safety Edge<sup>SM</sup> should be brought flush with the top of the pavement following paving. If this material should settle or be otherwise displaced in the future, however, the Safety Edge<sup>SM</sup> would continue to provide a durable height transition to smoothly conduct vehicles back to the paved road.<br />
<br />
The safety edge JSP must be included in all single-lift overlay projects when the finished surface will be 21 ft. wide or greater. This includes shoulder paving unless the paved width of each shoulder exceeds 4 ft. When using the Safety Edge<sup>SM</sup>, the quantity of asphalt mix will increase by approximately 2 percent.</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=30206606.1 Guardrail2012-11-08T21:34:51Z<p>Jonesjb: /* 606.1.3.1 3R/4R Projects */ Slightly re-worded for clarity</p>
<hr />
<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
<br />
<br />
==606.1.1 Types of Guardrail==<br />
<br />
'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
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'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
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'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
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'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
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==606.1.2 Guardrail Terms==<br />
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'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
<br />
'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
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'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
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'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
<br />
'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
<br />
==606.1.3 Applications==<br />
<br />
===606.1.3.1 3R/4R Projects===<br />
<br />
The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
<br />
* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Median pier protection] is to be installed in both directions on expressways and freeways when applicable.<br />
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* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
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* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
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* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
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* All existing guardrail not warranted by present standards is to be removed.<br />
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* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
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* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
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:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
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:2. Warranted by an analysis of accident history or,<br />
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:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
<br />
<div id="4. On NHS Routes only as required by current design criteria."></div><br />
:4. On NHS Routes only as required by current design criteria.<br />
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* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
<br />
* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
<br />
Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
<br />
On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
<br />
:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
<br />
===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
<br />
Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
<br />
An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
<br />
'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
<br />
'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
<br />
'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.24 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
<br />
Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
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===606.1.3.10 Bridge Piers and Sign Trusses===<br />
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Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
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===606.1.3.11 Signs===<br />
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Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
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===606.1.3.12 Outer Roadways===<br />
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Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
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===606.1.3.13 Headwalls===<br />
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Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
<br />
When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
<br />
===606.1.3.14 Medians===<br />
<br />
Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
<br />
Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
<br />
[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
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===606.1.3.15 Restricted Lateral Clearance===<br />
<br />
When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
<br />
===606.1.3.16 Barricade of Existing Streets and Roads===<br />
<br />
Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
<br />
===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:731_Precast_Reinforced_Concrete_Manholes_and_Drop_Inlets&diff=30016Category:731 Precast Reinforced Concrete Manholes and Drop Inlets2012-10-10T16:34:59Z<p>Jonesjb: /* 731.1.1 Measurement for Payment */ Clarified the depth measurement for drop inlets.</p>
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<div>==731.1 Design==<br />
All concrete drop inlets in the standard plans and specifications are precast. Contractors are permitted to substitute cast in place drop inlets to the dimensions required for precast drop inlets. If special conditions require specifying cast in place concrete drop inlets, such as retrofit projects, special sheets are available by contacting Engineering Policy in the Design Division. Details for each type of precast drop inlet are shown in the standard plans.<br />
<br />
===731.1.1 Measurement for Payment===<br />
Measurement of precast concrete drop inlets, complete in place, will be measured to the nearest 1 ft. for the depth of the drop inlet. Depth is defined as the vertical distance from the uppermost precast section to the invert flowline as shown on the standard drawing. Grates and bearing plates or curved vane grates and frames are paid for as separate items.<br />
<br />
===731.1.2 Type T Drop Inlets===<br />
Where two or more units of Type T drop inlets are required, measurement for payment will be the number of units times the depth, i.e., three units at 6 ft. depth, the pay quantity being 18 ft.<br />
<br />
===731.1.3 Quantity Sheet Procedure (Column Headings)===<br />
The suggested column headings for the accepted arrangement on the quantity sheet is as follows:<br />
*Col. 1 Station<br />
*Col. 2 Location<br />
*Col. 3 Type - A, B, C etc.<br />
*Col. 4 Depth "D" - As detailed in culvert sections. Depth is rounded to the nearest foot for each inlet for payment listed under appropriate size, i.e., "D" of 3.5 ft. would be 4.0 ft., "D" of 3.3 ft. would be 3.0 ft.<br />
*Col. 5 Grates and Bearing Plates or Curved Vane Grates and Frames from [http://modot.mo.gov/business/standards_and_specs/documents/61410.pdf Standard Plan 614.10] or [http://modot.mo.gov/business/standards_and_specs/documents/61410.pdf Standard Plan 614.11] by size of opening.<br />
*Col. 6 Class 3 Excavation<br />
*Col. 7 Remarks - Number and size of pipe openings required, etc.<br />
<br />
==731.2 Construction Inspection for [http://modot.mo.gov/business/standards_and_specs/Sec0731.pdf Sec 731]==<br />
These items are usually cast at a manufacturing plant and inspected by Division of Construction and Materials. Sometimes contractors elect to do their own precasting. If they do, the work should be inspected in accordance with applicable portions of Sec [http://modot.mo.gov/business/standards_and_specs/Sec1033.pdf 1033], [http://modot.mo.gov/business/standards_and_specs/Sec1055.pdf 1055], [http://modot.mo.gov/business/standards_and_specs/Sec1057.pdf 1057], and [http://modot.mo.gov/business/standards_and_specs/Sec1066.pdf 1066].<br />
<br />
Final measurements are not required except for authorized changes which should be added to or deducted from plan quantity. The inspector should record enough information in a field book to show how the unit was built and this entry should be signed by the inspector.<br />
<br />
==731.3 Material Inspection and Laboratory Inspection for Sec 731==<br />
See [[:Category:1033 Precast Drainage Units|Precast Drainage Units]].</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:Minor_Routes_Shouldering_Project_Guidelines&diff=29888Category:Minor Routes Shouldering Project Guidelines2012-09-17T20:05:43Z<p>Jonesjb: /* Minimum Expectations */</p>
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<div>Shoulders of any width provide the proven safety benefit of extra recovery area for errant vehicles. The public perceives shoulders as an enhancement to the transportation system and have consistently identified them as a top tier desire. In response, MoDOT has challenged their districts to assemble funding from any source possible and provide as many miles of shoulders on its minor routes as possible. The following guidelines are offered as an aid to facilitate the design of these projects. <br />
<br />
==Minimum Expectations==<br />
<br />
:* The finished roadway has a consistent 2-4 ft. wide paved shoulder.<br />
<br />
:* [http://epg.modot.org/index.php?title=Category:626_Rumble_Strips Edgeline rumble stripes] are provided.<br />
<br />
:* No right of way is acquired except in unique, isolated circumstances.<br />
<br />
:* Ditches, however altered, will flow properly.<br />
:* A Safety Edge<sup>SM</sup> will be constructed at the edge of each 4 ft. wide or narrower shoulder. <br />
<br />
:* The traveled way should be overlaid with a 1 in. level course flush with the finished shoulder surface.<br />
<br />
==Corridor Consistency==<br />
<br />
:* Districts will collaborate on corridors that cross district lines.<br />
<br />
:* Corridors will have logical termini.<br />
<br />
:* In general, shoulder improvements should appear the same (to the public).<br />
<br />
==NEPA==<br />
<br />
:* A standard [[127.1 Request for Environmental Services|RES]] will be submitted for each project.<br />
<br />
:* All projects will be classified as [http://epg.modot.mo.gov/index.php?title=127.14_National_Environmental_Policy_Act_(NEPA)_Classification_and_Documents#127.14.3.1_Categorical_Exclusion Categorical Exclusions (CE)].<br />
<br />
:* Impacts to [[127.7 Threatened and Endangered Species (T&E)|threatened and endangered species]] or known [[127.2 Historic Preservation and Cultural Resources|cultural resources]] should be discerned.<br />
<br />
==Conceptual Plans==<br />
<br />
:* Shouldering jobs fall under the Federal 3R classification as defined in [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div5&view=text&node=23:1.0.1.7.18&idno=23 23CFR 625.2(b)], however.<br />
<br />
:* A conventional [[:Category:128 Conceptual Studies|Conceptual Study Report]], instead of 3R, will be prepared.<br />
<br />
:* The appropriate rural and urban 3R standards will apply to design.<br />
<br />
:* Where 3R standards cannot be met, design exceptions will be submitted on a corridor-wide basis.<br />
<br />
:* The [http://www.highwaysafetymanual.org/Pages/default.aspx ''Highway Safety Manual''] (HSM) analysis required of design exceptions may be waived given the narrowly focused scope of shouldering.<br />
<br />
==Roadside Hardware==<br />
<br />
:* All blunt ends, turned-down ends, and BCTs will be replaced with [http://epg.modot.mo.gov/index.php?title=606.1_Guardrail#606.1.3.2_Approved_Crashworthy_End_Terminals crashworthy end terminals].<br />
<br />
:* The length of need (LON) need not be adjusted unless accident history or district policy presents the need to do so.<br />
<br />
:* Guardrail that is in place but no longer needed will be removed.<br />
<br />
:* If the height to the top of the guardrail is less than 26 ½ in. after construction, it should be increased to 29 inches. If the rail adjustment cannot be accommodated within the scope of the project, a design exception must be executed.<br />
<br />
==Rumble Stripes==<br />
<br />
:* On rural sections, a 12 in. [[:Category:626 Rumble Strips|rumble stripe]] should be milled straddling the line between shoulder and traveled way.<br />
<br />
:* In the event that the traveled way has not been overlaid, a 12 in. rumble stripe should be milled entirely on the shoulder surface, abutting the joint.<br />
<br />
:* Centerline rumble stripes may be milled in isolated locations if the accident history reveals the need to do so.<br />
<br />
==Signing==<br />
<br />
:* Signs should be located as specified in [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Std. Plan 903.02].<br />
<br />
:* Signs not meeting Std Plan 903.02 may be relocated by Maintenance forces, or justified by [[131.1 Design Exception Process|design exception]].<br />
<br />
==Drainage Structures==<br />
<br />
:* A 2 ft. minimum width shoulder will be provided over all pipes 36 in. or less in diameter. To accomplish this, <br />
<br />
::* Pipes may be extended, or<br />
<br />
::* Slopes may be warped within reason. <br />
<br />
:* Shoulders may be narrowed or discontinued over box culverts and pipes over 36 in. in diameter.<br />
<br />
==Constructability==<br />
<br />
Plans should include the [[media:Modified Shoulder JSP.doc|''Modified Shoulder Construction'' JSP]] which gives the contractor the option to pave the mainline and build the shoulders monolithically. The pavement team will determine if this method is applicable for areas of poor subgrade or shoulder widths wider than 2 feet.</div>Jonesjbhttps://epg.modot.org/index.php?title=File:409_JSP_Sept_2012.doc&diff=29872File:409 JSP Sept 2012.doc2012-09-13T19:02:59Z<p>Jonesjb: uploaded a new version of "Image:409 JSP Sept 2012.doc"</p>
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<div></div>Jonesjbhttps://epg.modot.org/index.php?title=230.2_Vertical_Alignment&diff=29825230.2 Vertical Alignment2012-09-05T19:37:04Z<p>Jonesjb: /* 230.2.10 Bridge Considerations */ Clarified intent of design exception.</p>
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<div>{|style="padding: 0.3em; margin-left:15px; border: 1px solid #cccccc; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right" <br />
|- <br />
||'''Figures'''<br />
|-<br />
|[[media:Decision Sight Distance.pdf|'''Green Book Exhibit 3-3''' "Decision Sight Distance"]] <br />
|-<br />
|[[Media:Elements of Passing Sight Distance for Two-Lane Hwy.pdf|'''Green Book Exhibit 3-4''' "Elements of Passing Sight Distance for Two-Lane Highways"]]<br />
|-<br />
|[[Media:Passing Sight Dist for Design of Two-Lane Hwy.pdf|'''Green Book Exhibit 3-7''' "Passing Sight Distance for Design of Two-Lane Highways"]] <br />
|-<br />
|[[Media:Design Controls for Sag Vertical Curves-Open Road Cond..pdf|'''Green Book Exibit 3-74''' "Design Controls for Sag Vertical Curves-Open Road Conditions"]]<br />
|-<br />
|[[Media:Design Controls for Sag Vertical Curves.pdf|'''Green Book Exhibit 3-75''' "Design Controls for Sag Vertical Curves"]]<br />
|}<br />
<br />
<br />
The topography of the land traversed has an influence on the alignment of roads and streets. Topography affects horizontal alignment, but it has an even more pronounced effect on vertical alignment. Variations in topography are generally separated into three classifications according to terrain:<br />
* '''Level'''---Highway sight distances, as governed by horizontal and vertical restrictions, are generally long or can be made so without construction difficulty of major expense.<br />
* '''Rolling'''---Natural slopes consistently rise above and fall below the road or street grade, and occasional steep slopes offer some restriction to the normal horizontal and vertical alignment.<br />
* '''Mountainous'''---Longitudinal and transverse changes in the elevation of the ground with respect to the road or street are abrupt, with benching and side excavation frequently needed to obtain acceptable horizontal and vertical alignment.<br />
<br />
These classifications pertain to the general character of a specific roadway corridor. Roadways in valleys, passes, or mountainous areas that have all the characteristics of roads or streets traversing level or rolling terrain should be classified as level or rolling. Generally, rolling terrain generates steeper grades than level terrain, causing trucks to reduce speeds below those of passenger cars; mountainous terrain has even greater effects, causing some trucks to operate at crawl speeds.<br />
<br />
==230.2.1 Rural Major Roads==<br />
[[image:230.2.1.jpg|right|300px]]<br />
<br />
The operational characteristics of a roadway are directly affected by the length and steepness of the vertical alignment. The designer is to consider the road’s terrain, traffic volume, expected capacity, LOS and other safety factors in order to properly anticipate the posted speed. Highways will be designed according to their anticipated posted speed as opposed to an arbitrary design speed.<br />
<br />
Once the anticipated posted speed is identified, the road’s vertical alignment can be selected. The AASHTO publication ''A Policy on Geometric Design of Highways and Streets'' (the Green Book) can be used as guidance to determine the maximum vertical grades.<br />
<br />
When terrain or some other factor causes the maximum grade to be impractical for a roadway segment, a grade in excess of those indicated in the Green Book can be incorporated into the design and the posted speed for that roadway decreased.<br />
<br />
==230.2.2 Urban Major Roads==<br />
[[image:230.2.2.jpg|right|400px]]<br />
<br />
While the operational characteristics of a roadway are directly affected by the length and steepness of the vertical alignment, extensive steep terrain in urban areas is not typically encountered. While no maximum grade for urban roads is specified, the Green Book’s table “Recommended Maximum % Grades for Rural Major Roads” can be consulted to determine an urban major road’s grade.<br />
<br />
==230.2.3 Minor Roads==<br />
<br />
Terrain, traffic volume and the anticipated posted speed are to be considered when selecting a roadway’s maximum vertical grade.<br />
<br />
==230.2.4 Sight Distance==<br />
<br />
Sight distance is the length of the roadway ahead that is visible to the driver. Sight distance is an element of design that affects the safe and efficient operation of a roadway and it is given careful consideration during the location study and preparation of the preliminary plan. Stopping sight distance, based on the anticipated posted speed, is the sum of the distance for braking reaction and the braking distance required for a driver to stop the vehicle after sighting an object on the roadway. Passing sight distance, based on the anticipated posted speed, is the minimum distance required to safely make a normal passing maneuver on two-lane roadways at passing speeds representative of nearly all drivers. Operational sight distance is a portion of the passing sight distance and is the minimum distance necessary for safe passing at the prevailing speed of traffic (85th percentile speed). Operational sight distance is used by the Traffic Division in establishing no passing zones by marking yellow lines on the roadways. Minimum design controls have been established for stopping and passing sight distances. Consideration for the design of a longer vertical curve to provide for operational sight distance is based on good engineering judgment and economy<br />
<br />
==230.2.5 Stopping Sight Distance and K Factors==<br />
<br />
The minimum stopping sight distances and “K” factors for various anticipated operating speeds are given in the Green Book. These controls are based on a 3.5 ft. height of eye and a 2.0 ft. height of object. The “K” factors are approximate only and are used as a guide in determining the length of the vertical curve. K values are a measure of passenger comfort. Use of small K values is not recommended. The stopping sight distance, as determined by formula, is used as the final control. Where practical, vertical curves at least 300 ft. in length are used. [[Media:Design Controls for Sag Vertical Curves.pdf|Exhibit 3-75]] of the AASHTO Greenbook is used to determine the length of a vertical curve required for any SSD based on change in grade.<br />
<br />
==230.2.6 Decision Sight Distance==<br />
<br />
Decision sight distance is used where the stopping sight distance is inadequate to allow a reasonably competent driver the distance to react to potentially hazardous situations. This condition may be present in a roadway environment that is cluttered visually, an intersection congested with traffic, a median crossover, or has an unusual roadway geometric configuration. In decision areas the decision sight distance gives a greater margin for error and provides the distance to maneuver a vehicle safely. See [[media:Decision Sight Distance.pdf|Exhibit 3-3]] of the AASHTO Green Book for decision sight distance values.<br />
<br />
==230.2.7 Passing Sight Distance==<br />
<br />
Passing sight distance for use in design is determined on the basis of the length needed to complete normal passing maneuvers in which the passing driver can determine that there are no potentially conflicting vehicles ahead before beginning the maneuver. While there may be occasions to consider a multiple passing (where two or more vehicles pass or are passed) it is not practical to assume such conditions in developing design criteria. Instead, sight distance is determined for a single vehicle passing a single vehicle. Longer sight distances occur in design of a roadway and such locations can accommodate an occasional multiple passing. Minimum passing sight distances for design of two-lane roadways incorporates certain assumptions about driver behavior. Actual driver behavior in passing maneuvers varies widely. To accommodate these variations, the design criteria for passing sight distance should accommodate the behavior of a high percentage of drivers rather than the “average” driver.<br />
<br />
The minimum passing sight distance for two-lane roadways is determined as the sum of the following four distances:<br />
<br />
* The distance traversed during perception and reaction time including initial acceleration.<br />
* The distance traveled while passing in the left lane.<br />
* The distance between the passing vehicle at the end of the maneuver and the opposing vehicle.<br />
* The distance traveled by the opposing vehicle for two-thirds of the time the passing vehicle occupies the left lane (see [[Media:Elements of Passing Sight Distance for Two-Lane Hwy.pdf|Exhibit 3-4]] of the Green Book).<br />
<br />
[[Media:Passing Sight Dist for Design of Two-Lane Hwy.pdf|Exhibit 3-7]] of the AASHTO Green Book can be used to determine passing sight distances for various speeds. These values are based on a 3.5 ft. height of eye and a 3.5 ft. height of object. [[230.1 Horizontal Alignment|Horizontal alignment]] is also considered in determining the location, extent, and percentage of passing distances. If passing maneuvers are to be performed on upgrades under the same assumptions about the behavior of the passing and the passed vehicles, the passing sight distance should be greater than the derived design values. Specific adjustments for design use are not available; however, the designer should recognize the desirability of exceeding the values shown in Exhibit 3-7 where practicable.<br />
<br />
Procedures in the Highway Capacity Manual indicate another criterion for passing sight distance design on two-lane roadways that are several miles in length. The available passing sight distance along this length can be summarized to show the percentage of length with greater-than-minimum passing sight distance. Analysis of capacity related to this percentage can indicate whether or not alignment and profile adjustments are needed to accommodate the design hourly volume (DHV). When roadway sight distances are analyzed over the whole range of lengths within which passing maneuvers are made, a new design criterion may be evaluated. Where high traffic volumes are expected on a roadway and a high [[902.12 Glossary#Level of Service (LOS)|level of service]] is to be maintained, frequent of nearly continuous passing sight distances are to be provided.<br />
<br />
Passing sight distance is not a design consideration for divided lane facilities.<br />
<br />
==230.2.8 Sag Vertical Curve Controls==<br />
<br />
At least four different criteria for establishing lengths of sag vertical curves are recognized to some extent. They are:<br />
<br />
* Headlight sight distance<br />
* Passenger comfort<br />
* Drainage control<br />
* General appearance<br />
<br />
The "K" factors shown in [[Media:Design Controls for Sag Vertical Curves-Open Road Cond..pdf|Exibits 3-74]] and [[Media:Design Controls for Sag Vertical Curves.pdf|3-75]] of the Green Book are for the most part based upon headlight sight distance and are to be used in the design of sag vertical curves. Where practicable, vertical curves at least 300 ft. in length are used.<br />
<br />
In some restrictive situations, the sag “K” factor determined above may be reduced to satisfy passenger comfort criteria. The length of vertical curves needed to satisfy the “comfort factor” at the posted speed is about 50 percent of that needed to satisfy the headlight sight distance criterion for the normal range of design conditions. The following formula (based on 3-51 of the Green Book) may be used to determine the length of the sag vertical curve for the reduced K factor.<br />
<br />
::::::::::<math>L = \frac{AV^2}{46.5}</math><br />
<br />
<br />
where:<br />
:::::L = length of sag vertical curve (ft.)<br />
:::::A = algebraic difference in grades (percent)<br />
:::::V = anticipated posted speed (mph)<br />
<br />
==230.2.9 Intersections==<br />
<br />
Important sideroads should intersect the through roadway at a -1% rate of grade from the shoulder of the through roadway, if practicable. When the -1% rate is not practicable, the grade is designed with good engineering judgment, keeping in mind the difference in grade between the cross slope of the through roadway and the grade of the sideroad. The sideroad grade will discourage accumulation of water at the edge of the through roadway. It will also provide a relatively flat grade for a distance necessary to allow storage for stopping traffic. Detailed information concerning intersection design can be found in the article entitled [[233.2 At-Grade Intersections with Stop and Yield Control|At-Grade Intersections]].<br />
<br />
==230.2.10 Bridge Considerations==<br />
<br />
It is desirable to avoid vertical and horizontal curves on bridges. When a horizontal curve is unavoidable on a bridge, spirals and superelevations are not to be placed on the bridge itself unless absolutely necessary. To facilitate drainage, it is preferable that level grades not be used on a bridge; however, if the bridge is on a level grade, the roadway profile grade is to be kept as level as possible for a distance of 50 ft. from the ends of the bridge at locations where the approaching roadway grade is below the bridge elevation. This will reduce the impact load on the bridge. Flat grades and sag curves can cause drainage problems on bridges, especially those over railroads or other roadways, and should be avoided. To avoid drainage problems, the low point of a sag curve will not be placed on the bridge unless absolutely necessary.<br />
<br />
[[748.7 Bridge Reports and Layouts#748.7.4.4 Grades|Minimum vertical clearances over roadways]] will be maintained. The Design Division must approve use of a reduction of vertical clearance below the minimum, as a [[131.1 Design Exception Process|design exception]]. Once approved, the project manager will notify the District Construction and Materials engineer to ensure measurement and posting of the final vertical clearance is accomplished.<br />
<br />
==230.2.11 Grades==<br />
<br />
The profile grade in a flood plain is established to keep the roadway’s shoulder a minimum of 1 ft. above design high water. This applies to all types of roadways. The stream gradient must be considered in establishing profile grades in flood plains. The Bridge Division will determine the design high water elevation to be used in establishing the profile grade.<br />
<br />
==230.2.12 Ramps==<br />
<br />
Grade considerations for [[233.2 At-Grade Intersections with Stop and Yield Control|at-grade intersections]] also apply to the area where an interchange ramp intersects a crossroad. Where ramps merge with the through roadway, grades are established by projecting the through roadway profile grade to the edge of the ramp pavement, using crown and controlling cross slopes at sufficient points in the vicinity of the ramp nose to determine a grade for the ramp in this area. Otherwise grade control for ramps are the same as for other roads, based on the anticipated posted speed. Additional information concerning [[230.2 Vertical Alignment#230.2.1.8 Sag Vertical Curve Controls|sag vertical curves]] can be helpful when establishing grade controls for ramps.<br />
<br />
==230.2.13 Outer Roadways and Service Roads==<br />
<br />
Design controls for vertical alignment on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways and service roads]] are based on the anticipated operating speed just the same as the controls for other roadways. However, the vertical alignment is modified to the extent necessary to provide adequate service to adjacent properties. Grades in the vicinity of streams are established to provide at least the same service level in relation to the stream high water that existed prior to the roadway improvement.<br />
<br />
==230.2.14 Profile Grades on the Plans==<br />
<br />
The profile grade information shown on the plans includes rate of grade, each P.I. station and elevation, length of vertical curves, the vertical curve "K" factors, and the stopping sight distance for crest vertical curves. P.I. stations are shown to the nearest 0.01 ft. P.I. elevations are shown to the nearest 0.01 ft. The length of vertical curve is set in 10 ft. increments. The "K" factor is shown to the nearest whole number. The stopping sight distance is shown in 5 ft. increments. All data for profile grades on outer roadways, service roads, and other roads are shown on plans in the same manner.<br />
<br />
When [[:category:207 Linear Grading#207.1 Class 1 Linear Grading|Linear Grading, Class 1]], is used a computed profile grade is not shown on the plans. When [[:category:207 Linear Grading#207.2 Class 2 Linear Grading|Linear Grading, Class 2]], is used a dashed grade line is shown on the plans only where it is necessary to control the grade. This differentiates Linear Grading, Class 2, from Volume Grading.<br />
[[image:230.2.jpg|center|750px|thumb|<center>'''Undated photo'''</center>]]<br />
[[category:230 Alignment of the Roadway|230.2]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:Minor_Routes_Shouldering_Project_Guidelines&diff=29589Category:Minor Routes Shouldering Project Guidelines2012-08-03T16:57:48Z<p>Jonesjb: /* Minimum Expectations */ Safety Edge added as minimum requirement.</p>
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<div>Shoulders of any width provide the proven safety benefit of extra recovery area for errant vehicles. The public perceives shoulders as an enhancement to the transportation system and have consistently identified them as a top tier desire. In response, MoDOT has challenged their districts to assemble funding from any source possible and provide as many miles of shoulders on its minor routes as possible. The following guidelines are offered as an aid to facilitate the design of these projects. <br />
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==Minimum Expectations==<br />
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:* The finished roadway has a consistent 2-4 ft. wide paved shoulder.<br />
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:* [http://epg.modot.org/index.php?title=Category:626_Rumble_Strips Edgeline rumble stripes] are provided.<br />
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:* No right of way is acquired except in unique, isolated circumstances.<br />
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:* Ditches, however altered, will flow properly.<br />
:* A Safety Edge<sup>SM</sup> will be constructed at the edge of each shoulder. <br />
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:* The traveled way should be overlaid with a 1 in. level course flush with the finished shoulder surface.<br />
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==Corridor Consistency==<br />
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:* Districts will collaborate on corridors that cross district lines.<br />
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:* Corridors will have logical termini.<br />
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:* In general, shoulder improvements should appear the same (to the public).<br />
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==NEPA==<br />
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:* A standard [[127.1 Request for Environmental Services|RES]] will be submitted for each project.<br />
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:* All projects will be classified as [http://epg.modot.mo.gov/index.php?title=127.14_National_Environmental_Policy_Act_(NEPA)_Classification_and_Documents#127.14.3.1_Categorical_Exclusion Categorical Exclusions (CE)].<br />
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:* Impacts to [[127.7 Threatened and Endangered Species (T&E)|threatened and endangered species]] or known [[127.2 Historic Preservation and Cultural Resources|cultural resources]] should be discerned.<br />
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==Conceptual Plans==<br />
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:* Shouldering jobs fall under the Federal 3R classification as defined in [http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&rgn=div5&view=text&node=23:1.0.1.7.18&idno=23 23CFR 625.2(b)], however.<br />
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:* A conventional [[:Category:128 Conceptual Studies|Conceptual Study Report]], instead of 3R, will be prepared.<br />
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:* The appropriate rural and urban 3R standards will apply to design.<br />
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:* Where 3R standards cannot be met, design exceptions will be submitted on a corridor-wide basis.<br />
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:* The [http://www.highwaysafetymanual.org/Pages/default.aspx ''Highway Safety Manual''] (HSM) analysis required of design exceptions may be waived given the narrowly focused scope of shouldering.<br />
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==Roadside Hardware==<br />
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:* All blunt ends, turned-down ends, and BCTs will be replaced with [http://epg.modot.mo.gov/index.php?title=606.1_Guardrail#606.1.3.2_Approved_Crashworthy_End_Terminals crashworthy end terminals].<br />
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:* The length of need (LON) need not be adjusted unless accident history or district policy presents the need to do so.<br />
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:* Guardrail that is in place but no longer needed will be removed.<br />
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:* If the height to the top of the guardrail is less than 26 ½ in. after construction, it should be increased to 29 inches. If the rail adjustment cannot be accommodated within the scope of the project, a design exception must be executed.<br />
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==Rumble Stripes==<br />
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:* On rural sections, a 12 in. [[:Category:626 Rumble Strips|rumble stripe]] should be milled straddling the line between shoulder and traveled way.<br />
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:* In the event that the traveled way has not been overlaid, a 12 in. rumble stripe should be milled entirely on the shoulder surface, abutting the joint.<br />
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:* Centerline rumble stripes may be milled in isolated locations if the accident history reveals the need to do so.<br />
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==Signing==<br />
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:* Signs should be located as specified in [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Std. Plan 903.02].<br />
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:* Signs not meeting Std Plan 903.02 may be relocated by Maintenance forces, or justified by [[131.1 Design Exception Process|design exception]].<br />
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==Drainage Structures==<br />
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:* A 2 ft. minimum width shoulder will be provided over all pipes 36 in. or less in diameter. To accomplish this, <br />
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::* Pipes may be extended, or<br />
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::* Slopes may be warped within reason. <br />
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:* Shoulders may be narrowed or discontinued over box culverts and pipes over 36 in. in diameter.<br />
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==Constructability==<br />
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Plans should include the [[media:Modified Shoulder JSP.doc|''Modified Shoulder Construction'' JSP]] which gives the contractor the option to pave the mainline and build the shoulders monolithically. The pavement team will determine if this method is applicable for areas of poor subgrade or shoulder widths wider than 2 feet.</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=29500606.1 Guardrail2012-07-25T15:52:12Z<p>Jonesjb: Removed accidental replication</p>
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<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
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==606.1.1 Types of Guardrail==<br />
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'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
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'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
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'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
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'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
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==606.1.2 Guardrail Terms==<br />
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'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
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'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
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'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
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'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
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'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
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==606.1.3 Applications==<br />
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===606.1.3.1 3R/4R Projects===<br />
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The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
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* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. Median pier protection is to be installed in both directions on expressways and freeways when applicable.<br />
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* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
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* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
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* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
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* All existing guardrail not warranted by present standards is to be removed.<br />
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* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
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* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
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:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
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:2. Warranted by an analysis of accident history or,<br />
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:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
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:4. On NHS Routes only as required by current design criteria.<br />
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* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If this can be done and the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
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* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
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Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
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On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
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:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
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:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
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:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
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:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
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This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
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===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
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Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
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An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
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Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
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The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
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'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
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'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
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[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
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'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
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'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
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'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
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If any of the following conditions exists a Type E terminal should be used:<br />
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:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
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:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
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'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
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===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
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===606.1.3.4 Anchored in Backslope Guardrail===<br />
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In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
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===606.1.3.5 End Treatment===<br />
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The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
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===606.1.3.6 High Fills===<br />
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Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
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===606.1.3.7 Fixed Objects===<br />
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Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.24 of the ''Roadside Design Guide''.<br />
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===606.1.3.8 Aesthetic Guardrail===<br />
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Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
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There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
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Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
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No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
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===606.1.3.9 Bridge Ends===<br />
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Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
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On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
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The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
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Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
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Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
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Turned down ends offer a solution to terminating guardrail at some bridge ends, or other roadside obstacles, on certain, low-volume highways throughout the state. While the use of these terminals has generally been discontinued for new construction, they may represent appropriate design for roads with low traffic volumes, traveled by motorists who are generally familiar with the roadway and it’s geometrics.<br />
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Use of turned down ends is primarily governed by the parameters of speed and volume.<br />
Irrespective of any values for these parameters; however, the use of turned down ends are prohibited on the following:<br />
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:*[http://wwwi/intranet/tp/products/othermap/documents/major_highways_pp.pdf Major highways]<br />
:*The [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|National Highway System (NHS)]]<br />
:*Areas of poor geometry<br />
:*Areas with an accident history in excess of the statewide average for similar road<br />
:*Areas of posted speed 60 mph or greater<br />
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Neither an existing higher order end terminal, nor an existing turned down end installation is to be replaced with a new turned down end. The use of a turned down end should be limited to those areas where they will both yield an increase in safety over the existing situation and leave the area reasonably safe.<br />
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Turned down ends may represent reasonably safe design when the posted speed is less than 60 mph and the AADT is 400 or fewer vehicles per day.<br />
<br />
A [[131.1 Design Exception Process|design exception]] is to be obtained for every location in which a new turned down end treatment is proposed. This exception simply documents why the engineer believes the installation represents a reasonable level of safety<br />
<br />
Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
<br />
===606.1.3.10 Bridge Piers and Sign Trusses===<br />
<br />
Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
<br />
===606.1.3.11 Signs===<br />
<br />
Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
<br />
===606.1.3.12 Outer Roadways===<br />
<br />
Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
<br />
===606.1.3.13 Headwalls===<br />
<br />
Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
<br />
When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
<br />
===606.1.3.14 Medians===<br />
<br />
Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
<br />
Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
<br />
[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
<br />
===606.1.3.15 Restricted Lateral Clearance===<br />
<br />
When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
<br />
===606.1.3.16 Barricade of Existing Streets and Roads===<br />
<br />
Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
<br />
===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing with a minimum of 66 in. embedment will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.1_Guardrail&diff=29498606.1 Guardrail2012-07-25T13:49:20Z<p>Jonesjb: Published the new guardrail height requirements per FHWA and AASHTO.</p>
<hr />
<div>[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
<br />
<br />
==606.1.1 Types of Guardrail==<br />
<br />
'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
<br />
'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
<br />
'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
<br />
'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
<br />
==606.1.2 Guardrail Terms==<br />
<br />
'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
<br />
'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
<br />
'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
<br />
'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
<br />
'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
<br />
==606.1.3 Applications==<br />
<br />
[[image:606.1 GUARDRAIL.jpg|left|450px]]<br />
<br />
<br />
==606.1.1 Types of Guardrail==<br />
<br />
'''Type A Guardrail''' - single W beam rail with 6 ft. 3 in. post spacing.<br />
<br />
'''Type B Guardrail''' - double W beam rail (single beam on each side of post) with 6 ft. 3in. post spacing, generally for use in median.<br />
<br />
'''Type D Guardrail''' - single W beam rail with 12 ft. 6 in. post spacing for use at end of road or street.<br />
<br />
'''Type E Guardrail''' - single thrie beam rail with 3 ft. 1 ½ in. post spacing.<br />
<br />
==606.1.2 Guardrail Terms==<br />
<br />
'''End Anchor''' - a guardrail end device without a buffer end to develop the full strength of the rail system.<br />
<br />
'''Embedded End Anchor''' - an end anchorage system for guardrail whereby the rail is embedded in a concrete block and buried in the backslope.<br />
<br />
'''Rock Face End Anchor''' - an end anchorage system for guardrail whereby the rail is bolted to a rock face.<br />
<br />
'''Blockout''' - spacer block to separate the guardrail beam from the post used on all types of guardrail.<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="280px" align="right" <br />
|-<br />
|<center>'''Figures'''</center><br />
|-<br />
|[[Media:606.1 Warrant for Median Barriers.pdf|Warrant for Median Barriers]]<br />
|-<br />
|<center>'''Videos'''</center><br />
|-<br />
|These are very short video clips of guardrail crash tests conducted at the Midwest Roadside Safety Facility in Lincoln, Nebraska. The video image is very small (and typically located on the lower left of your screen) unless you click the video's enlarge button.<br />
|-<br />
|[[media:606.1 A successful pickup test, real time.wmv|A successful pickup test]]<br />
|-<br />
|[[media:606.1 A successful pickup test, slow motion.wmv|A successful pickup test, slow motion]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, real time.wmv|Another successful pickup test]]<br />
|-<br />
|[[media:606.1 Another successful pickup test, rear view.wmv|Another successful pickup test, rear view]]<br />
|-<br />
|[[media:606.1 A successful car test.wmv|A successful car test]]<br />
|-<br />
|[[media:606.1 An unsuccessful pickup test.wmv|An unsuccessful pickup test]]<br />
|-<br />
|MoDOT cooperates with other states in the [http://www.mwrsf.unl.edu/About.htm Midwest State's Regional Pooled Fund Program] to develop and improve new and innovative safety devices.<br />
|}<br />
<br />
'''Bullnose Guardrail System''' – an enclosed guardrail design that wraps a semi-rigid guardrail around a hazard.<br />
<br />
==606.1.3 Applications==<br />
<br />
===606.1.3.1 3R/4R Projects===<br />
<br />
The necessity of guardrail modifications as a part of a 3R/4R project must be evaluated when work is performed on any state-maintained roadway. As used here, "work" is defined as projects that involve raising the elevation of the travelway through resurfacing which requires height adjustment of the guardrail (as outlined below) or requiring any other adjustment of the guardrail, but does not include [[:Category:413 Surface Treatments and Preventive Maintenance|surface maintenance activities]] (i.e. patching, full depth repair, microsurfacing, seal coating, ultrathin bonded wearing surface, 1 ¾" thin lift overlay, and Recycled Asphaltic Pavement (RAP)).<br />
<br />
* On dual lane facilities, guardrail end terminals are to be upgraded with an approved crashworthy end terminal in both directions even if the project covers only rehabilitation of the roadway in one direction. Median pier protection is to be installed in both directions on expressways and freeways when applicable.<br />
<br />
* Guardrail or concrete barrier blunt ends located on either side of a two-way roadway or on the guardrail approach end of dual lane facilities must be replaced with an approved crashworthy end terminal even if the project covers only rehabilitation of the roadway in one direction.<br />
<br />
* All guardrail turned-down ends, concrete height transitions and Breakaway Cable Terminals (BCT) must be replaced with an approved crashworthy end terminal.<br />
<br />
* When crashworthy end terminals are installed, the guardrail is to be extended to provide the proper length of need to protect the roadside safety hazard based on current policy. The proper flat recovery area required for the end terminal, as recommended by the manufacturer, is to also be provided for on the plans.<br />
<br />
* All existing guardrail not warranted by present standards is to be removed.<br />
<br />
* New guardrail or remanufactured guardrail, not salvage rail, is to be used for all projects except those involving only guardrail height adjustment.<br />
<br />
* If no guardrail currently exists at a particular location along the roadway, then none is to be constructed as a portion of a project that provides only resurfacing of the roadway unless:<br />
<br />
:1. Other locations of guardrail are adjusted as described in this subsection or,<br />
<br />
:2. Warranted by an analysis of accident history or,<br />
<br />
:3. Obstacles are introduced within the clear zone (i.e. signing, signals, lighting, etc.), which require guardrail according to existing criteria or,<br />
<br />
:4. On NHS Routes only as required by current design criteria.<br />
<br />
* Wherever possible, and if the proposed shoulder slope does not exceed AASHTO recommendations, resurfacing of the shoulder is to be tapered to minimum thickness (½ in. aggregate size). If this can be done and the guardrail remains at a minimum height of 26 ½ in., no adjustments to the rail are necessary. The accepted AASHTO range in cross-slope for bituminous shoulders is 2% to 6%. If the shoulder surfacing cannot be tapered to minimum thickness without exceeding the 6% maximum, low guardrail must be raised to 29 in. New guardrail is to be constructed to present standards and the surfacing on the shoulder is to be constructed to the minimum slope in order to accept a future resurfacing without further modifying the guardrail. In any case, it is emphasized that the shoulder surfacing is not planned merely to justify guardrail modifications. A maximum of 8% algebraic difference in the slope of pavement and shoulder at the pavement edge is permitted.<br />
<br />
* Wherever the resurfacing of the travelway and the shoulders results in a relative guardrail height less than 26 ½ in., the height must be adjusted to 29 in. [[image:606.1 Delineator.jpg|right|225px|thumb|<center>'''[http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00] provides information for new guardrail delineators.'''</center>]]<br />
* Any unconnected bridge approach guardrail is to be connected to the bridge by an acceptable transition design. This work is to be accomplished in conjunction with any significant roadway work in the same area.<br />
<br />
Approved crashworthy end terminals meeting NCHRP 350 Test Level 3 (TL-3) criteria are to be used on all roadways with posted speed limits greater than 45 mph. Test Level 2 (TL-2) end terminals may be used on roadways with posted speed limits of 45 mph or less, and Test Level 1 (TL-1) end terminals may be used on roadways with posted speed limits of 30 mph or less. TL-1, TL-2, and TL-3 require successful tests of an 1800 lb. (800 kg) car impacting a barrier at 20 degrees, and a 4,400 lb. (2000 kg) pickup truck impacting a barrier at an angle of 25 degrees and at speeds of 30 mph, 45 mph, and 60 mph, respectively.<br />
<br />
On 3R/4R and safety improvement projects that include the installation of guardrail, it is important to upgrade the existing roadside elements in the following order:<br />
<br />
:1. All turned-down, blunt ends or other noncompliant NCHRP 350 end terminals must be replaced with an approved end terminal (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30]). Associated “length of need” improvements, include both upstream and downstream ends of the guardrail according to current design criteria, are also to be made. (Length of Need, or LON, is defined as the total length of a longitudinal barrier needed to shield an area of concern by containing or redirecting an errant vehicle.) As an element of this activity, existing guardrail constructed with steel blockouts and 6 ft. posts without 2 ft. of level ground behind the guardrail are to be left in place.<br />
[[image:606.1.3.1 Bridge Anchor Section.jpg|right|200px|thumb|<center>'''Bridge Anchor Section'''</center>]]<br />
:2. All noncompliant NCHRP 350 attachments of guardrail to a bridge end must be replaced using an approved bridge anchor section (see [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23] ).<br />
<br />
:3. In addition, guardrail is to be provided to close median bridge gaps.<br />
<br />
:4. When it is necessary to replace more than 50% of an existing length of guardrail (not constructed to existing criteria) as a result of slides or extensive damage, the entire length of guardrail is to be removed and replaced with new guardrail according to current design criteria.<br />
<br />
:5. Fixed objects within the clear zone of the mainline roadway are to be removed, relocated, redesigned or shielded in accordance with current design criteria. Fixed objects include non-breakaway signs and luminaries, trees, culvert ends, non-traversable drop inlets, etc. These improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
<br />
:6. Maintenance/Emergency crossovers located in the median are to be improved in accordance with current clear zone requirements. Additionally, the portion of interchange ramps located within the clear zone of the mainline roadway is to be upgraded. However, these improvements could be delayed until rehabilitation of the roadway surface is provided so long as the rehabilitation is contained in any of the first three years of the STIP.<br />
<br />
This listing is a guide for the design team to address individual guardrail improvements on individual projects. It is not intended to be a strict guide for the selection of projects or the allocation of funds.<br />
<br />
===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
<br />
Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
<br />
An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
<br />
Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
<br />
The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
<br />
'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
<br />
'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
<br />
[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
<br />
'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
<br />
'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
<br />
'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
<br />
If any of the following conditions exists a Type E terminal should be used:<br />
<br />
:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
<br />
:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
<br />
'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
<br />
===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.01]. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60630.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
<br />
===606.1.3.4 Anchored in Backslope Guardrail===<br />
<br />
In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
<br />
===606.1.3.5 End Treatment===<br />
<br />
The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
<br />
===606.1.3.6 High Fills===<br />
<br />
Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
<br />
===606.1.3.7 Fixed Objects===<br />
<br />
Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.24 of the ''Roadside Design Guide''.<br />
<br />
===606.1.3.8 Aesthetic Guardrail===<br />
<br />
Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
<br />
There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
<br />
Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
<br />
No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
<br />
===606.1.3.9 Bridge Ends===<br />
<br />
Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plans 606.22]and [http://www.modot.mo.gov/business/standards_and_specs/documents/60623.pdf 606.23]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
<br />
On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
<br />
The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
<br />
Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
<br />
Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
<br />
Turned down ends offer a solution to terminating guardrail at some bridge ends, or other roadside obstacles, on certain, low-volume highways throughout the state. While the use of these terminals has generally been discontinued for new construction, they may represent appropriate design for roads with low traffic volumes, traveled by motorists who are generally familiar with the roadway and it’s geometrics.<br />
<br />
Use of turned down ends is primarily governed by the parameters of speed and volume.<br />
Irrespective of any values for these parameters; however, the use of turned down ends are prohibited on the following:<br />
<br />
:*[http://wwwi/intranet/tp/products/othermap/documents/major_highways_pp.pdf Major highways]<br />
:*The [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|National Highway System (NHS)]]<br />
:*Areas of poor geometry<br />
:*Areas with an accident history in excess of the statewide average for similar road<br />
:*Areas of posted speed 60 mph or greater<br />
<br />
Neither an existing higher order end terminal, nor an existing turned down end installation is to be replaced with a new turned down end. The use of a turned down end should be limited to those areas where they will both yield an increase in safety over the existing situation and leave the area reasonably safe.<br />
<br />
Turned down ends may represent reasonably safe design when the posted speed is less than 60 mph and the AADT is 400 or fewer vehicles per day.<br />
<br />
A [[131.1 Design Exception Process|design exception]] is to be obtained for every location in which a new turned down end treatment is proposed. This exception simply documents why the engineer believes the installation represents a reasonable level of safety<br />
<br />
Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
<br />
===606.1.3.10 Bridge Piers and Sign Trusses===<br />
<br />
Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
<br />
===606.1.3.11 Signs===<br />
<br />
Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
<br />
===606.1.3.12 Outer Roadways===<br />
<br />
Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
<br />
===606.1.3.13 Headwalls===<br />
<br />
Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
<br />
When an obstacle such as a culvert headwall is located close to the shoulder line, a longer, unsupported span (up to 25 ft.) can be accomplished by omitting posts and double nesting the rail. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
<br />
===606.1.3.14 Medians===<br />
<br />
Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
<br />
Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
<br />
[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
<br />
===606.1.3.15 Restricted Lateral Clearance===<br />
<br />
When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
<br />
===606.1.3.16 Barricade of Existing Streets and Roads===<br />
<br />
Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
<br />
===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 23 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 23 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 23 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing with a minimum of 66 in. embedment will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]<br />
<br />
===606.1.3.2 [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal, Qualified Plastic Guardrail Block and Three-Strand Guard Cable System Tables|Approved Crashworthy End Terminals]]===<br />
[[image:606.1.3.2 Approved Crashworthy End Terminal.JPG|right|thumb|300px|<center>'''A Type A Crashworthy End Treatment'''</center>]]<br />
<br />
Crashworthy end terminals are the devices used to provide an acceptable level of safety to the end of a roadside barrier or fixed object. Such treatment is required because of the serious consequences that result from a vehicle impacting an untreated barrier. An untreated end can cause an impacting vehicle to abruptly stop, become unstable or roll; it can even penetrate the passenger compartment, all of which increase the risk to the vehicle’s occupants.<br />
<br />
An approved crashworthy end terminal is a device or system that has met the safety requirements contained in the NCHRP 350 and has been accepted by the FHWA. The safety requirements of NCHRP 350 are based on several parameters among which are rate of deceleration, tendency to roll, and penetration of the passenger compartment. Within NCHRP 350 are [[606.2 Guard Cable#Table 1 What is TL-3?|six different test levels]] that vary depending on the speed, angle of impact and weight or type of vehicle. The test level required for highways in the state highway system is usually Test Level 3 (TL-3). An end treatment satisfying this test level will safely handle the impact of vehicles as large as a 4,400 lb (2000 kg) pickup truck impacting at 62 mph (100 km/h). When the generic term “approved crashworthy end terminal” is used, it most often refers to a TL-3 device. Designers should refer to the information pertaining to crashworthy end terminals available on MoDOT’s website.<br />
<br />
Crashworthy end terminals located within 10 ft. of the edgeline will be marked with a Type 3 Modified Object Marker. <br />
<br />
The end terminals have been classified into five groups: Type A, B, C, D and E. The type of classification does not reflect any national standards, only MoDOT classification for specification purposes. Additional information on crashworthy end terminals and internet links to terminals approved by MoDOT are available at [http://www.modot.mo.gov/business/standards_and_specs/endterminals.htm. MoDOT's end terminal website] or [[:Category:1040 Guardrail, End Terminals, One-Strand Access Restraint Cable and Three-Strand Guard Cable Material#1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block|EPG 1040.4 Crashworthy End Terminal and Qualified Plastic Guardrail Block]].<br />
<br />
'''Type A Crashworthy End Terminal.''' A Type A terminal is an end treatment used for one-sided barriers such as roadside guardrail or roadside concrete barrier. Type A devices can also be used on one-sided barriers in [[231.1 Median Width|the median]], provided sufficient clear space is available behind the system to allow opposite direction traffic to recover from an errant path.<br />
<br />
'''Type B Crashworthy End Terminal.''' A Type B terminal is an end treatment used for double-sided barrier, most often in the median. Such a device can safely be impacted from several angles including, in most cases, the entirely opposite direction. Type B terminals cannot, however, be installed in paved surface locations unless the installation is temporary and the paved area is to be resurfaced after the system’s removal.<br />
<br />
[[image:606.3.2 Type C.jpg|left|225px||thumb|<center>'''A Type C Crashworthy End Treatment'''</center>]]<br />
<br />
'''Type C Crashworthy End Terminal.''' A Type C terminal is an end treatment used for double-sided barrier, in gore areas and in [[231.1 Median Width|the median]]. Like the Type B, this device can be safely impacted from several angles usually ranging from head-on to the entirely opposite direction. Type C terminals, however, may be installed in both paved and unpaved surface locations, but must be installed on an asphalt or concrete pad in non-paved areas.<br />
<br />
'''Type D Crashworthy End Terminal.''' A Type D terminal has all of the installation and performance parameters of the Type C, but must be at least 80% reusable and have the ability to be reset manually with minimal or no repairs. Type D terminal should be used in gore areas or medians where moderately frequent impacts are expected, i.e., more than one impact every two years. <br />
<br />
'''Type E Crashworthy End Terminal.''' A Type E terminal has all of the installation and performance parameters of the Type C, but is a self-restoring unit that functions properly after at least 2 impacts, without any manual resetting procedures. <br />
<br />
If any of the following conditions exists a Type E terminal should be used:<br />
<br />
:* Gore areas or medians with a high frequency of expected impacts, i.e., more than one impact every year. <br />
<br />
:* Geometrics and/or traffic volumes present greater than normal potential for harm to workers during repair.<br />
<br />
'''Sand Barrels.''' Sand barrels are a crash cushioning system most often used to shield fixed objects that cannot be removed or relocated. Sand barrels are recommended for temporary usage such as in work zones. A benefit/cost analysis is to be conducted before sand barrels are used in a permanent application. For more information, refer to [[:category:612 Impact Attenuators#612.2 Sand-Filled Impact Attenuators (Sand Barrels)|EPG 612.2 Sand-Filled Impact Attenuators (Sand Barrels)]].<br />
<br />
===606.1.3.3 Bullnose Guardrail System===<br />
[[image:606.1.3.3.jpg|right|280px]]<br />
The bullnose guardrail system is to be used in the medians of expressways or freeways to shield drivers from hazards, such as bridge piers and other obstacles. It is not a crashworthy end terminal, but is rather a non-gating barrier principally constructed of Type E guardrail. As long as the median’s vertical differences are minimal or can be graded, the bullnose guardrail system is the preferred treatment for new construction. The bullnose guardrail system requires at least 15 ft. of median width for its construction. The bullnose guardrail system is not to be erected between twin bridges. Alternatives are available for twin bridge protection in [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.01]. Alternatives requiring a [[131.1 Design Exception Process|design exception]] are available for bridge pier and other median hazard protection. Consult [http://www.modot.mo.gov/business/standards_and_specs/documents/60601.pdf Standard Plan 606.30] for grading requirements and other important details.<br />
<br />
===606.1.3.4 Anchored in Backslope Guardrail===<br />
<br />
In areas of a roadway cut section, or where the road is transitioning from cut to fill, designers are encouraged to consider the application of anchored in backslope guardrail. Often this can be accomplished by extending the guardrail beyond the length-of-need to tie the guardrail into the backslope. When properly designed and located, this type of anchor provides full shielding for the identified hazard, eliminates the possibility of an end-on impact with the terminal, and minimizes the likelihood of the vehicle passing behind the rail.<br />
<br />
===606.1.3.5 End Treatment===<br />
<br />
The guardrail is to be extended outside of the clear zone, or the guardrail end is to be embedded into an adjacent embankment or attached to a solid rock face to eliminate the need for a crashworthy end terminal. If these options are not practical, all approach ends of guardrail, as illustrated by the standard plans, are provided with an approved crashworthy end terminal and a separate payment is made for each crashworthy end terminal. The district is to indicate on the plans where a crashworthy end terminal is to be installed. All downstream ends on two-way roadways are provided with an approved crashworthy end terminal. Downstream ends on dual lane highways need only be treated with end anchors.<br />
<br />
===606.1.3.6 High Fills===<br />
<br />
Guardrail for embankments is specified on plans for roads with 400 AADT or more. For roads under 400 AADT, guardrail is optional, however, good design judgment requires guardrail when conditions warrant. Guardrail is not normally warranted for embankment height on projects where clear zones are utilized. However, guardrail may be warranted as shown on Figs. 5.1 through 5.3 in the ''AASHTO Roadside Design Guide''. Combinations of embankment height and slope that plot above the curve indicate a need for guardrail. Combinations plotting below the curve indicate conditions are less severe without guardrail. However, other factors contributing to accident severity such as hazards located either on or at the toe of the slope are to be taken into consideration.<br />
<br />
===606.1.3.7 Fixed Objects===<br />
<br />
Guardrail protection for fixed objects such as trees or utility poles may be necessary. If this protection is required, the protection is determined from the near lane on one-direction roadways and from both lanes on a two-direction roadway. Guardrail is warranted in advance of any fixed object located within the clear zone provided the object is potentially more damaging than the guardrail if struck by a vehicle and the object cannot be economically removed, relocated, or made crashworthy by means of breakaway type construction. The fixed object is termed the area of concern and the required type and length of guardrail depends on the size of the object, the distance from the travelway, the AADT, and the design speed. The length of need of guardrail is the length of the obstacle plus the length of the approach barrier adjacent to traffic (and opposing lane, if needed). The length of need and the flare rate of the guardrail shall be determined in accordance with the procedures contained in Section 5.6.4 of the ''AASHTO Roadside Design Guide''. The general geometric data covering the length of need are illustrated on Figure 5.24 of the ''Roadside Design Guide''.<br />
<br />
===606.1.3.8 Aesthetic Guardrail===<br />
<br />
Aesthetic guardrail is available for projects located along [http://www.modot.org/scenicbyways/ scenic highways], at scenic overlooks or at other locations where a rustic appearance may be appropriate. Wood, composite or recycled materials are often the primary constituents of this type of guardrail. Because aesthetic guardrail would be expected to cost more than typical guardrail, additional funding shall come from the local jurisdictions, enhancement funds, other non-department sources or a combination of these.<br />
<br />
There are no aesthetic crashworthy end treatments approved by MoDOT. Designers incorporating aesthetic guardrail on a project are to refer to the information pertaining to crashworthy end treatments available on MoDOT’s website. Designers are to be aware that for the proper design of guardrail from some manufacturers, the length of need is to begin at least 100 feet downstream from the terminal.<br />
<br />
Care is to be taken by the designer to consider whether a specific appearance is desired for the aesthetic guardrail. If a specific appearance is deemed appropriate in order to coordinate with existing facilities or some other aspect of the scenic location, the designer is to specify the system desired with a Job Special Provision.<br />
<br />
No approved end terminal exists for most types of aesthetic guardrail. Therefore, in these cases, the end of the rail must be terminated into a backslope or extended to a point outside the clear zone. [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Specifications in Sec 606] have been prepared in anticipation of the eventual production of approved end terminals for aesthetic guardrail.<br />
<br />
===606.1.3.9 Bridge Ends===<br />
<br />
Guardrail is placed at bridge ends in accordance with typical locations shown in the standard plans for all roads. Approved crashworthy end terminals are provided on guardrail placed for bridge end protection. Guardrail placed for bridge end protection is anchored to the bridge end by a bridge anchor section. In retrofit projects having non-standard transitions and slopes, the connector plates for bridge anchor sections may be slightly adjusted to produce a vertical terminal connector. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60622.pdf Standard Plan 606.22]. Existing bridge end connections that do not conform to current standards are to be considered for replacement or modification. In order to determine the appropriate solution for the specific non-standard bridge end connection, the Bridge Division Liaison Engineer is to be consulted. Where guardrail at the downstream end of a one-way bridge is necessary because of a high fill or other condition, the guardrail is connected to the bridge anchor section. <br />
<br />
On certain low-volume highways throughout the state, bridge ends may be delineated in lieu of shielding. This option is viable where the operating speed is less than 60 mph and the AADT is 400 or fewer vehicles per day. <br />
<br />
The delineation-only option is primarily governed by the parameters of speed and volume. Irrespective of any values for these parameters, however, the use of delineation-only is prohibited on Major Highways (Principal Arterials and above) as well as the National Highway System (NHS).<br />
<br />
Use of the delineation-only option is not recommended on bridge ends in areas of poor geometry (horizontal alignment, vertical alignment, sight distance, etc.). Nor is it recommended in areas with an accident history (as calculated between two points at least 0.25 miles from either approach) in excess of the statewide average for similar road. If further analysis of either of these situations proves the delineation option to be viable, then a design exception should be obtained for its use. <br />
<br />
Additionally, the delineation-only option should be limited to those bridge replacements or rehabilitations where the existing structure was unshielded and the existing roadway template cannot reasonably accommodate the installation of guardrail without some modification.<br />
<br />
Turned down ends offer a solution to terminating guardrail at some bridge ends, or other roadside obstacles, on certain, low-volume highways throughout the state. While the use of these terminals has generally been discontinued for new construction, they may represent appropriate design for roads with low traffic volumes, traveled by motorists who are generally familiar with the roadway and it’s geometrics.<br />
<br />
Use of turned down ends is primarily governed by the parameters of speed and volume.<br />
Irrespective of any values for these parameters; however, the use of turned down ends are prohibited on the following:<br />
<br />
:*[http://wwwi/intranet/tp/products/othermap/documents/major_highways_pp.pdf Major highways]<br />
:*The [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|National Highway System (NHS)]]<br />
:*Areas of poor geometry<br />
:*Areas with an accident history in excess of the statewide average for similar road<br />
:*Areas of posted speed 60 mph or greater<br />
<br />
Neither an existing higher order end terminal, nor an existing turned down end installation is to be replaced with a new turned down end. The use of a turned down end should be limited to those areas where they will both yield an increase in safety over the existing situation and leave the area reasonably safe.<br />
<br />
Turned down ends may represent reasonably safe design when the posted speed is less than 60 mph and the AADT is 400 or fewer vehicles per day.<br />
<br />
A [[131.1 Design Exception Process|design exception]] is to be obtained for every location in which a new turned down end treatment is proposed. This exception simply documents why the engineer believes the installation represents a reasonable level of safety<br />
<br />
Guardrail is not generally used to protect traffic from the ends of bridges carrying a crossroad or street over the through lanes in developed areas where speed controls exist or sidewalks are provided. If however, at ends of such bridges the roadway is in a high fill or has sharp curvature, guardrail may be considered.<br />
<br />
===606.1.3.10 Bridge Piers and Sign Trusses===<br />
<br />
Guardrail is specified for protection of traffic from bridge piers and sign trusses with the exception of those piers and trusses where the footings are located outside the clear zone. Typical treatments are indicated in the standard plans. Bridge piers located close to the roadway are marked with a Type 2 Object Marker.<br />
<br />
===606.1.3.11 Signs===<br />
<br />
Guardrail protects traffic from signposts that cannot be equipped with a breakaway assembly. Typical treatments are indicated in the standard plans.<br />
<br />
===606.1.3.12 Outer Roadways===<br />
<br />
Criteria for guardrail use on [[232.5 Freeways#Outer Roads and Service Roads|outer roadways]] are the same as for other roads except for the shoulder side adjacent to a through lane. Guardrail is specified along outer roadways where the outer roadway is 10 ft. or more above the main roadway, and the shoulder of the outer roadway is less than 25 ft. from the top of the roadway backslope. Sometimes it is more economical to move the outer roadway back sufficiently to eliminate the requirement for guardrail. Guardrail along outer roadways is installed with the face of the rail toward the outer roadway. Type B guardrail may be required if the guardrail is within the limits of the clear zone for the through lanes.<br />
<br />
===606.1.3.13 Headwalls===<br />
<br />
Guardrail is usually not used to protect traffic from headwalls located outside of the shoulder line of roadways without clear zones unless warranted by high fills. Exceptions include interstate safety modification projects where clear zones are not added and where it may not be economically feasible to extend a large box culvert to locate the headwall outside the clear zone point.<br />
<br />
When an obstacle such as a culvert headwall is located close to the shoulder line, the guardrail can be “double-nested” by skipping a post. This allows motorist safety to be enhanced by providing uninterrupted guardrail instead of transitioning to other forms of barrier. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/60600.pdf Standard Plan 606.00]. Headwalls located within the shoulder or immediately adjacent to the roadway on two-lane, two-way roads are marked with a [[903.15 Other Signing Items#903.15.5 Type 3 Object Marker|Type 3 Object Marker]]. These object markers are not used on interstates, full shoulder-width bridges or at obstructions outside the shoulder point.<br />
<br />
===606.1.3.14 Medians===<br />
<br />
Guardrail may be specified [[231.1 Median Width|in medians]] to provide a positive barrier. Guardrail may also be specified to convert an existing raised curb median to a barrier median provided the center of the guardrail is placed 21 in. above the pavement elevation at the curb face. Type B guardrail may be used on a raised median width of 2 ft. back-to-back. For greater widths, two single lines of Type A guardrail will be required. For medians of variable widths, a detail in the standard plans provides for transition from Type B to Type A guardrail. Approved crashworthy end terminals are added only at the beginning and ending of a total run of guardrail and not at each break caused by intersections and median openings. Breaks caused by intersections and median openings will be closed by means of a crashworthy special end treatment. For medians on divided pavements where grade differential will not permit standard clear zones, the slope is to be modified to provide as safe a slope treatment as possible. Guardrail will not be required except for exceptional or unusual conditions.<br />
<br />
Type B guardrail can be used on a flush median, as shown in the figure below. Type B guardrail is to be used where a median barrier is to be provided but site conditions will not permit the use of a concrete barrier (drainage, visibility requirements, aesthetics, etc.). The concrete barrier is generally limited to the high volume roadways with narrow width medians. Many existing freeways have medians that are wider than 36 ft. (11 m). These medians are of sufficient width to satisfy clear zone requirements, thus making the provision of guard cable optional. <br />
<br />
[[image:606.1 Warrants for Median Barriers English.jpg|center|thumb|'''Warrant for Median Barriers'''|675px]]<br />
<br />
===606.1.3.15 Restricted Lateral Clearance===<br />
<br />
When piers or other obstacles require guardrail treatment, the back of the guardrail post is to be placed 4 ft. from the pier or obstacle. Where the clearance obtained is less than 4 ft. but more than 2 ft., 25 ft. of Type E guardrail shall be used preceding and through the limits of the obstacle. There will be situations with narrow shoulders or with curbed medians when encroachment is not permitted. In such cases, Type E guardrail is to be specified requiring 25 ft. preceding the obstacle and extending through the limits of the obstacle as required. The minimum offset to the obstacle can be eliminated completely by attaching the rail to the obstacle by use of a bridge anchor section.<br />
<br />
===606.1.3.16 Barricade of Existing Streets and Roads===<br />
<br />
Where an essentially rural street or road is to be closed for less than approximately five years, permanent barricades as shown on [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Standard Plan 903.02] and are specified. When the closing of the street or road is anticipated to exceed approximately five years in essentially rural areas, and for closing streets or roads in essentially urban areas regardless of time, either Type 4 Object Markers only or a combination of Type 4 Object Markers and Type D guardrail is specified. Where no hazard exists beyond the end of the closed street or road for a reasonable distance, Type 4 Object Markers are sufficient for delineation. Where a hazard exists beyond the end of the closed street or road that is considered equal to or greater than that created by the use of guardrail, a combination of both Type 4 Object Markers and Type D guardrail is specified. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/90303.pdf Standard Plan 903.03].<br />
<br />
===606.1.3.17 Plans===<br />
<br />
Guardrail details and typical locations for installation are shown in the standard plans. Guardrail is shown by proper legend on the plan sheets and the station location and quantities are tabulated on the 2B sheets. Quantities are tabulated in 12 ft. 6in. increments. Curved sections of guardrail are to be installed on curves with a radius of 150 ft. or less. The plans specify the lengths of curved guardrail and the radius of curvature. Curved guardrail is not tabulated separately on the plans. Examples of [[620.5 Delineators (MUTCD Chapter 3F)#620.5.5 Guardrail Delineation|guardrail delineation]] and tabulation are shown in [[media:235 Sample Preliminary Plans.pdf|Sample Plans]].<br />
<br />
===606.1.3.18 Urban Section, Curb and Curb and Gutter===<br />
<br />
Where barrier curb is used, guardrail is placed with the face at the face of the curb and the center of the rail 21 in. above the pavement elevation at the curb face. Where mountable curb is used, guardrail is placed with the face at the edge of the usable shoulder and the center of the rail 21 in. above the shoulder elevation. Where curb and gutter is used, guardrail is placed with the face at the face of curb and the center of the rail 21 in. above the gutter line. When curbs are constructed directly beneath guardrail, the curb height shall be 4 inches.<br />
<br />
===606.1.3.19 Use of 7 ft. Guardrail Posts===<br />
<br />
When a 2-ft. offset for embankments behind the guardrail is not available, 7 ft. guardrail posts at 3 ft. 1½ in. spacing with a minimum of 66 in. embedment will be required. It is to be noted that the standard plans for many two-lane and dual-lane facilities constructed in the 1960s and early 1970s show an additional 2 ft. offset for embankments placed in front of or behind the guardrail. A field review by the Design Division personnel of selected projects constructed in the 1960s and early 1970s revealed that in most cases the edge of the travelway and the embankment were separated by 12 ft., at least 10 ft. of which was a paved shoulder. This additional width, or 2 ft. offset, which was usually unpaved, is present even though the typical sections for these projects do not show it.<br />
[[image:606.1.3.19 Slide area.jpg|right|250px|thumb|<center>'''Slide Area'''</center>]]<br />
Due to this fact, designers are to conduct a field check to determine whether additional width is available for projects involving extending or replacing guardrail. This field check is to include the District Soils and Geology Technician to determine whether the embankment has eroded or if a slide has occurred. If the original 12 ft. width has significantly eroded, it is to also be determined whether the 2 ft. offset can be restored without causing additional failure.<br />
<br />
If the 2 ft. offset was not originally constructed at the location, a cost analysis is to be conducted to determine whether to add a 2 ft. offset to the slope or use 7 ft. posts with 3 ft. 1 ½ in. spacing.<br />
<br />
==606.1.4 Maintenance Planning Guidelines for Guardrail==<br />
<br />
'''Printable''' [[media:R227 - Guardrails.pdf|'''Maintenance Planning Guideline for Guardrail''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=29497606.2 Guard Cable2012-07-25T13:39:27Z<p>Jonesjb: /* 606.2.4.1 Lateral Placement in the Median */ Wordsmithing</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
{|style="padding: 0.3em; margin-left:1px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes occur on highways with median widths above MoDOT's initial 60 ft. threshold. No route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history that effectly removes them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed no more than 4 ft. downslope of the edge of the shoulder. With wider shoulders, the downslope location could be less than 4 ft., but in any case, there must be 8 ft. between the barrier and the edge of traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions. <br />
<br />
If the 8 ft. separation cannot be obtained, the designer must work with the Central Office Design Division to assess the potential safety impacts of a decreased deflection distance. If the arrangement cannot be proven reasonably safe, a different barrier system must be used.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' Three [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use one slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since three equivalent sources exist, there is not need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|public interest finding]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter. If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter. No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. A steeper side approach slope may allow a passenger vehicle to duck under the guard cable and subsequently not be stopped. The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=29496606.2 Guard Cable2012-07-25T13:37:27Z<p>Jonesjb: /* 606.2.4.1 Lateral Placement in the Median */ Clarified the parameters of lateral placement of high-tension cable barriers in the median.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
{|style="padding: 0.3em; margin-left:1px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes occur on highways with median widths above MoDOT's initial 60 ft. threshold. No route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history that effectly removes them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed no more than 4 ft. downslope of the edge of the shoulder. With wider shoulders, the downslope location could be less than 4 ft., but in any case, there must be 8 ft. between the barrier and the edge of traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions. <br />
<br />
If the 8 ft. deflection distance cannot be obtained, the designer must work with the Central Office Design Division to assess the potential safety impacts of a decreased deflection distance. If the arrangement cannot be proven reasonably safe, a different barrier system must be used.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' Three [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use one slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since three equivalent sources exist, there is not need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|public interest finding]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter. If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter. No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. A steeper side approach slope may allow a passenger vehicle to duck under the guard cable and subsequently not be stopped. The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:130_Value_Engineering&diff=28824Category:130 Value Engineering2012-04-27T20:00:41Z<p>Jonesjb: /* 130.1.3 VE Workplan/Project Selection */ Added cost thresholds for federally required Value Engineering Studies</p>
<hr />
<div>[[Image:130 Value Engineering Study.jpg|right|400px]]<br />
<br />
<br />
<br />
==130.1 Discussion==<br />
<br />
Value Engineering (VE) is a systematic method of examining performance to improve the value of projects or processes. Value is defined as the ratio of performance to cost and thus capable of being increased by either lowering the cost or improving the performance. MoDOT’s values and tangible results place increased importance on value-based, practical design. While VE, in the classic sense, tends to be somewhat more structured, VE and [[:Category:143 Practical Design|Practical Design]] are truly one and the same. The goal of VE is to build the right project at the right time, achieving delivery of project purpose and need with proper project scope.<br />
{|style="padding: 0.3em; margin-right:5px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Practical Design'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri07003/ss07005.pdf Summary 2007]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right" <br />
|-<br />
|'''Additional Information'''<br />
|-<br />
|[[media:130 District Value Engineering Contact.doc|District Value Engineering Coordinator's Responsibilities]]<br />
|-<br />
|[[130.3 Project Manager’s Guide|Project Manager's Guide]]<br />
|-<br />
|[[130.4 Value Engineering Team Leader Guide|Value Engineering Team Leader Guide]]<br />
|-<br />
|[[media:130.1 VE Training Evaluation Form.doc|VE Training Evaluation Form]]<br />
|-<br />
|[[media:C-104.doc|Construction Value Engineering Change Proposal (C-104)]]<br />
|-<br />
|[[104.13 Construction Inspection Guidance for Sec 104#104.13.1 Guidance for Sec 104.6|Evaluation Procedures for Construction Value Engineering Change Proposals]]<br />
|-<br />
|[http://www.modot.mo.gov/ValueEngineering/VEContacts.htm MoDOT Value Engineering Contacts]<br />
|}<br />
MoDOT uses VE to ensure that the public receives full value for every tax dollar invested in Missouri’s transportation system. VE techniques are used to improve productivity in nearly every aspect of MoDOT’s operation, including practices, processes, and procedures. In highway construction, VE encourages contractors to submit proposals for modifying the plans, specifications or other requirements of the contract to deliver improved projects of the best possible value.<br />
<br />
===130.1.1 Study Timing===<br />
<br />
Although only a single study is generally required for a project’s design, VE studies can be performed any time prior to letting. It is even possible to perform multiple studies on an individual project. A study can be done at any stage during the design life of the project, however, priority is given to performing the study as early as feasible to maximize the opportunity to implement developed alternatives. During the study, all aspects of the project may be considered including, but not limited to, location, geometrics, final vertical and horizontal alignments, drainage, construction staging, traffic control, and signalization, pavement and structure details. In addition, studies in the later phase should consider what additional flexibility can be added and adjustments can be made to "fine tune" before the project letting.<br />
<br />
VE studies are performed to add value to a project, not to simply reduce costs. VE studies should challenge project scoped that exceed the minimum necessary to deliver the project’s purpose and need. As stated in the law, VE studies are made "to provide suggestions for reducing the total cost of the project and providing a project of equal or better quality."<br />
<br />
===130.1.2 VE Organization===<br />
Value Engineering is a critical program and requires participation to accomplish program goals. The Innovations Engineer (IE) manages the overall operation of MoDOT’s VE program. The IE is responsible for tracking the VE program and reporting its progress to both management and the FHWA. The IE leads studies and may assist with the initial selection of teams for district VE studies, and provides training guidelines and facilitation. <br />
Each District Engineer selects a district value engineering coordinator (DVEC) to coordinate VE activities in that district. The [[media:130 District Value Engineering Contact.doc|DVEC is responsible]] for the district's VE program. The DVEC should be at a level consistent with the supervision and management responsibilities of the VE effort. The DVEC is responsible for scheduling the study and making appropriate accommodations for the participants. The DVEC serves as a team member on the VE study to become familiar with the process and leads VE studies as required to meet the demands of the program. The DVEC is also responsible for tracking the District led value engineering studies and ensuring the study results are forwarded to the IE and entered into the SIMS database for each specific project. <br />
<br />
In any case, the facilitator of the study compiles recommendations from the VE study and submits them in VE report, for approval as follows: <br />
<br />
:* The lowest level decision maker as approved by the district can approve and implement VE recommendations that do not change policy, standards or the scope of the original project. A copy of the VE study and the Project Manager’s, District Design Engineer or District Engineers approval is retained by the district and the IE. The IE notifies the team members of the study results and tracks results of each study. <br />
<br />
:* The approval of a District Engineer or division engineer is required to approve and implement VE recommendations that change the scope of the original project. A copy of the VE study and the District Engineer or division engineers’ approval is retained by the district and the IE. The IE tracks results of each study. <br />
<br />
:* The approval of the Chief Engineer, or his representative, is required to approve and implement VE recommendations that affect more than one division/district or that change policy or standards. The IE notifies affected divisions, districts and the team members and tracks results of each study. <br />
<br />
===130.1.3 VE Workplan/Project Selection===<br />
<br />
Each year, a value engineering work plan for the federally required Value Engineering Studies is completed after approval of the MoDOT highway right of way and construction program. The federal requirements are:<br />
* a project with an estimated total cost of $25 million or more<br />
* a bridge project with an estimated total cost of $20 million or more <br />
* any other project designated by the Secretary of Transportation<br />
<br />
Projects which meet the minimum criteria for requirement are identified and submitted to FHWA for their concurrence, identifying those projects for which value analysis has been previously conducted and the date of that study. The DVECs will assist the IE in identifying the appropriate projects. <br />
<br />
A district value engineering workplan will be created by each DVEC to identify the district’s projects which will be the priority on which to conduct a Value Engineering effort. The DVEC may use the [[media:130 VE Project Selection Criteria.doc|VE project selection criteria]] to aid in determine which projects have the greatest potential for study. The DVEC sends the district’s annual study schedule to the IE for retention and to supplement the MoDOT VE work plan. <br />
<br />
Divisions or districts may also request VE studies at any point throughout the year. Project VE studies are generally done at the district level. VE studies on procedures, processes, specifications, standard plans and details of statewide impact are generally done at the division level. <br />
<br />
The VE study report and recommendations are conveyed to the appropriate staff upon completion of the study. Affected districts and divisions will receive copies of the study as soon as practical after its completion. The DVEC works with project managers to evaluate the recommendations of the VE team. The project managers submit responses to the study recommendations to the IE.<br />
<br />
===130.1.4 VE Study Process===<br />
<br />
The formal VE process entails a systematic process of review and analysis of a project during its design/project development phase, resulting in recommendations to improve value while addressing the project’s purpose and need. A VE study has 3 distinct phases outlined below:<br />
<br />
* '''Pre-Study Phase:''' The IE works with the TPM and DVEC to set up the study (see the [[130.3 Project Manager’s Guide|Project Manager's Guide]] for additional information).<br />
<br />
* '''Study Phase:''' A multidisciplinary team conducts the VE review by investigating and analyzing the planning, design, and constructability of a project;<br />
:*identifying project functions and costs and worth;<br />
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|-<br />
|'''Related Information Video'''<br />
|-<br />
|[[media:130.1.6 LifeCycle.wmv|'''Life Cycle of a Highway''']]<br />
|}<br />
:*creatively speculating on alternate ways to perform the various functions;<br />
:*evaluating the best and/or least life-cycle alternatives;<br />
:*developing acceptable alternatives into supported recommendations; and<br />
:*presenting the team’s recommendations to the appropriate staff.<br />
<br />
* '''Post Study Phase:''' Approval and implementation of VE recommendations and finalizes the VE Report. The VE Report should consist of:<br />
:* The names and contact information for the participants<br />
:* A description of the project<br />
:* A summary of the functional determination or consideration given for the project.<br />
:* A listing of the generated alternative solutions<br />
:* The anticipated savings costs associated with each alternative<br />
:* A copy of the district’s or division’s response indicating accepted alternatives and anticipated savings.<br />
:* Any additional pertinent information associated with the study.<br />
<br />
===130.1.5 VE Study Types===<br />
<br />
There are several types of VE studies:<br />
<br />
====130.1.5.1 Traditional Studies====<br />
'''Concept Stage VE (CSVE).''' The focus is on coming up with many alternates, the goal being to choose the best alternate to accomplish project P&N. It works best for the CSVE to be conducted prior to signing DEIS or before conceptual submittal if a CE. (3 to 5 day study). A full VE report is prepared.<br />
<br />
'''Preliminary Stage VE (PSVE).''' The traditional VE study conducted prior to preliminary plan submittal. The focus here is usually on improving the existing design, often, by this stage, the footprint is usually set and it may be too late for major functional enhancements. (3 to 5 day study). Afull VE report is prepared.<br />
<br />
'''Final Design Stage VE (FDVE).''' A traditional VE study conducted near the end of the design process. The focus here is on improving the design, providing flexibility and considering alternatives that meet the purpose and need. This is likely the least effective phase to conduct the study as most of design features will have been committed to and significant changes may be required to implement new alternatives, however project improvement is still possible. A full VE report is prepared.<br />
<br />
====130.1.5.2 Non-Traditional Studies====<br />
<br />
Because of the value of minimizing unnecessary effort being spent on design work which would be later changed, there is a real benefit to conducting Concept Stage VE studies which help develop multiple alternates to best identify the right solution. However, often the VE/Practical Design Review’s conducted during the final design build consensus through collaboration and ensures the most practical solution, reducing last minute scrutiny of projects. Project managers can use VE as a proven problem-solving system and can realize secondary benefits including better project scope definition and increased value by optimizing the ratio of project performance and project cost. <br />
<br />
'''Compressed Value Engineering Study.''' An abbreviated, yet thorough, analysis which follows the standard VE Job Plan but is conducted in a compressed time frame using techniques designed to reduce the required time frame to fully consider the project and alternatives. It may take anywhere from 4 hours to 3 days and is commensurate with the complexity of the project. The study may be conducted at any stage from conceptual to final plans.<br />
<br />
:* Use technology to maximize time for functional analysis and solution development.<br />
:* May use a Pre-Develop functional analysis, which is expanded in study to meet any unique project features.<br />
:* After ranking, the alternative solutions are developed just far enough to validate and generate costs. Additional design effort necessary to address acceptance and implementation decisions questions or concerns and the full design is accomplished by the project design staff.<br />
<br />
'''Alternative Value Analysis (AVA) (A Practical Design Review with functional analysis).''' An abbreviated, yet thorough, analysis conducted quickly (anywhere from 2 hours to 3 days, commensurate with the complexity of the project) at any stage from conceptual to final plans, which is led by the PM, the Design Liaison Engineer or the DVEC. An abbreviated VE report is prepared. The report should contain at a minimum, the participants, all identified alternatives, the accepted alternatives and an estimate of any cost savings associated with the alternatives. <br />
:* Team composition- Consists of Central Office and district staff. Teams may be small, only 3 to 5 persons, or large, mirroring project core teams.<br />
:* May follow either the traditional or compressed Value Engineering study process.<br />
:* Findings may be reported in a simple letter format<br />
<br />
'''Combined Project Type Value Studies.'''<br />
:* Multiple projects of the similar scope and size are grouped together for the study. A composite analysis is conducted with unique features of each project discussed and considered accordingly, however the focus should remain on the individual project traits and not on the program guidelines.<br />
<br />
:* The compressed study process may also be used.<br />
<br />
'''Constructability Review.''' This type of VE study that concentrates on constructability, traffic management, "bidability", innovative contracting, etc. Can be done at any stage from conceptual to final plans. The study length can be anywhere from 2 hours to 5 days. <br />
<br />
:* It generally consists of or coincides with a meeting of MoDOT personnel and interested contractors to discuss their perspective on construction aspects associated with the draft plans. <br />
<br />
:* If a meeting with the industry is conducted during this process, the preliminary plans should be posted with the meeting notice at least one week prior to provide opportunity to schedule attendance and review the proposed plans. <br />
<br />
:* The meeting should not be mandatory, to avoid unnecessary impacts to the bidding environment for the project.<br />
<br />
'''Programmatic Value Engineering Studies.''' This programmatic study type is used when studying entire programs for consideration of process and program value improvement. The functional perspective and associated alternatives are considered in the development or review of the guidelines in order to have projects within the program that are of the greatest value. The emphasis is placed on the improving the guidance that will be subsequently used for project development. The high level study should focus on the function of the program more than the individual projects. The study could be conducted in a traditional manner or based upon the compressed study type. The study length will likely be less than 1 day.<br />
<br />
'''Process Value Analysis.''' This type of VE study concentrates on process improvement. The goal is to take an innovative and practical look at any process. Subjects could include anything, for example, maintenance operations, construction standards or purchasing specifications. The study length can be 2 to 5 days.<br />
<br />
===130.1.6 [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|NEPA]] Considerations===<br />
<br />
Given the potential for impacts to resources outside the [[127.14 National Environmental Policy Act (NEPA) Classification and Documents|NEPA]] study area or changes to previously approved designs, the environmental and historic preservation sections will have a stake in most VE studies; however, decisions and/or agreements from environmental studies and public hearings can be questioned. Members from one or both sections can provide the team with needed information to help in the process.<br />
<br />
When VE studies are conducted post-NEPA, caution '''must''' be exercised to ensure when VE decisions contradict any commitments that are made in a standing, approved NEPA document. This would also apply to assumptions made for post-NEPA approvals, such as Section 404 permits, approvals from the U.S. Fish and Wildlife Service, as well as others. Although VE decisions may negatively impact environmental or public hearing agreements, these decisions may be made provided the time, cost and effort for the supplemental studies or hearings should be considered. All valid suggestions should be included in the study report for management’s consideration. <br />
<br />
===130.1.7 Value Engineering Study Numbering Convention===<br />
In order to properly track all value engineering effort, a numbering convention for tracking both Central Office and district Value Engineering efforts is provided.<br />
<br />
====130.1.7.1 District Value Engineering Efforts====<br />
The DVEC shall ensure that each value engineering effort performed by the district is properly documented under the appropriate VE number. The district value engineering number will consist of the District Designation followed by the year followed by the study number to three digits, starting with one. For example, Central District's first district led value engineering effort of 2012 would be numbered CD 2012-001.<br />
<br />
====130.1.7.2 Central Office Value Engineering Efforts====<br />
The IE shall ensure that each value engineering effort performed by the Central Office is properly documented under the appropriate VE number. The Central Office value engineering number will consist of the year followed by the study number to three digits, starting with one. For example, the first Central Office-led value engineering effort of 2012 would be numbered 2012-001.<br />
<br />
===130.1.8 Additional Information===<br />
<br />
The FHWA's ''Value Engineering for Highways'' provides further details on the VE technique and its applicability to highway projects and functions. Copies may be obtained from the FHWA VE coordinator. in addition, AASHTO’s ''Guidelines for Value Engineering, 2nd Edition'' provides an excellent description of VE and the process steps.<br />
<br />
MoDOT’s [[130.4 Value Engineering Team Leader Guide|Value Engineering Team Leader Guide]] and [[130.3 Project Manager’s Guide|Project Manager’s Guide]] offer specific, in-depth information for those involved in these respective capacities.<br />
<br />
==130.2 Contractor initiated VECPs==<br />
<br />
Contractor initiated [[media:C-104.doc|Value Engineering Change Proposals]] (VECPs) and Practical Design Value Engineering Change Proposals (PDVECPs) are handled in accordance with [http://www.modot.mo.gov/business/standards_and_specs/Sec0104.pdf Sec 104.6 of the Missouri Standard Specifications for Highway Construction]. The process used to evaluate the change proposal is presented in [[104.13 Construction Inspection Guidance for Sec 104#104.13.2 Value Engineering Proposals (Sec 104.6)|EPG 104.13 Construction Inspection Guidance for Sec 104]]. <br />
<br />
VECPs provide a product of equal or improved quality by reducing the project’s total cost, improving the project’s safety, or decreasing the time required to complete the project. This proposal is initiated by the contractor (using the VE Change Proposal) who receives 50% of the savings associated with the proposal should it be approved by MoDOT. <br />
<br />
A PDVECP may provide a product of lesser value; use an existing item in place or underrun contract items. The PDVECP shall not adversely affect safety or function of the final product. This proposal is initiated by the contractor, using the [[104.13 Construction Inspection Guidance for Sec 104#104.13.1 Guidance for Sec 104.6|VE change proposal]] who receives 25% of the savings associated with the proposal should it be approved by MoDOT. <br />
<br />
All reasonable documented engineering costs incurred by the contractor to design and develop a value engineering proposal shall be reimbursed and subtracted from the savings of the construction costs. All costs incurred by MoDOT to review and implement the VECP will be at the Commission’s expense.<br />
<br />
For example, a contractor submits a VECP with a reduction in construction costs of $100,000. The documented engineering costs for the proposal total $20,000. The actual net savings are determined by subtracting the engineering costs ($20,000) from the reduced construction cost ($100,000). In this example, the net savings is $80,000 that is split between MoDOT and the contractor using either the 50/50 or 75/25 ratio dependent upon the type of VE approved.<br />
<br />
Examples of Value Engineering Proposals can be found on the [http://www.modot.mo.gov/ValueEngineering/index.htm Value Engineering Web Page].</div>Jonesjbhttps://epg.modot.org/index.php?title=606.2_Guard_Cable&diff=28535606.2 Guard Cable2012-04-17T14:53:52Z<p>Jonesjb: /* 606.2.5 Maintenance and Repair */ Removed superfluous text.</p>
<hr />
<div>{|style="padding: 0.3em; margin-left:10px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="250px" align="right" <br />
|-<br />
|'''For Additional Information'''<br />
|-<br />
|[[media:Guard Cable Program 2007.pdf|"MoDOT's Cable Median Barrier Program"]], a report from 2007.<br />
|-<br />
|[http://www.savemolives.com/programs/documents/I70GuardCableStateFair--updated.ppt Installing Guard Cable and Safety Information about Guard Cable]<br />
|-<br />
|'''Videos'''<br />
|-<br />
|[{{SERVER}}/documents/606.2_Cable_Rail_Test.mpg Successful guard cable test]<br />
|-<br />
|[[media:606.1 Guard cable.wmv|Guard Cable in Action]]<br />
|-<br />
|[http://www.youtube.com/modotvideo#p/u/1/IZTtBN7CHxY MoDOT's You Tube Guard Cable video]<br />
|}<br />
<br />
==606.2.1 Guard Cable Types==<br />
<br />
Cable median barriers, commonly referred to as guard cable, remain one of the most efficient roadside safety treatment available today. Guard cable consists of twisted wire ropes mounted on weak posts. It is relatively inexpensive to install, compared to more rigid systems, and has been proven effective at capturing errant vehicles.<br />
There are two types of guard cable systems in use on Missouri roads: low-tension and high-tension. <br />
<br />
'''606.2.1.1 Low-Tension.''' Since no single producer exclusively manufactures low-tension guard cable, this system has been commonly called the “U.S. generic” system. Low-tension guard cables typically consists of three cables placed at different heights and are tensioned only enough to eliminate sag between posts. Large springs at either end of the cable run are compressed, according to temperature, to achieve the system’s low tension. The cable itself is strung on posts that are directly driven into the ground.<br />
[[image:606.2 Guard Cable.JPG|right|400px|thumb|<center>'''Low-tension Guard Cable'''</center>]]<br />
When a vehicle impacts the low-tension system under normal conditions, the cable laterally moves as much as 12 ft. This movement is known as the dynamic deflection.<br />
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|-<br />
|'''Median Guard Cable'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri06014/ss07006.pdf Summary, 2006]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri08039/or10016.pdf Report, 2010]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Given the lack of tension in the system, individual installations, or “runs”, of cable are limited to 2000 ft. with an anchor assembly at each end. When a vehicle strikes low-tension cable, the system becomes disabled and will not function properly if subsequently struck by another vehicle. As such, it is critical to repair the guard cable promptly.<br />
<br />
Low-tension systems have been in service for some time and have proven their value by reducing cross-median accidents. However, the issues related to down time and the necessity to utilize on-call contracting cause a perpetual drain on MoDOT resources. For these reasons, the use of low-tension cable systems should be limited to small-scale installations with special circumstances.<br />
<br />
'''606.2.1.2 High-Tension.''' High-tension cable barrier looks very similar to low-tension cable but the two systems are very different in most other aspects. High-tension guard cable consists of three or four pre-stressed cables supported by weak posts. <br />
[[image:606.2.1.2 High-Tension.jpg|right|575px|thumb|<center>'''High-tension Guard Cable'''</center>]]<br />
During installation, the cables are placed on the posts and then tightened to a specific tension, ranging from approximately 2,000 to 9,000 pounds according to temperature. Due to this tightening, the cable installations can be of indefinite length. In fact, the runs are typically only limited by the presence of obstacles such as median openings or bridge columns.<br />
<br />
Under normal conditions, when a vehicle impacts the high-tension system the cable laterally deflects as much as 8 ft. The inherent tension within the system also allows the cable to remain at the proper height, even after an impact removes several posts. While the system is not designed to continue to function in that condition, there is a great deal of anecdotal evidence that it does just that.<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right"<br />
|+'''Currently Approved High-Tension Systems and Manufacturers''' <br />
! style="background:#BEBEBE"|High-Tension System !! style="background:#BEBEBE"|Manufacturer <br />
|-<br />
|Brifen|| Brifen USA <br />
|-<br />
|CASS||Trinity Industries, Inc. <br />
|-<br />
|Gibraltar||Gibraltar <br />
|-<br />
|Safence||Safence, Inc. <br />
|-<br />
|U.S. High Tension|| Marion Steel Company <br />
|}<br />
<br />
A common installation of high-tension guard cable employs concrete footings into which metal tubes are cast, forming sockets. The socket allows a post to be replaced with relative ease during a repair operation. The damaged post is simply removed from the socket and replaced with a virgin post. Socketed systems eliminate the requirement for specialized post driving equipment and subsurface utility location for each repair.<br />
<br />
A socketed, high-tension system should be chosen for large-scale guard cable installations. While such a system generally has a higher initial cost, the low cost and high efficiency with which it can be maintained make it a better value over its life cycle. A high-tension system incorporating socketed posts is easily repaired and maintained with the resources currently available to the district maintenance personnel. Additionally, high-tension systems can be used on a variety of median inslopes, often eliminating the need for costly slope corrections and drainage modifications.<br />
<br />
As of 2007, all high-tension systems are proprietary, that is, marketed under exclusive rights of a specific manufacturer. Five systems are currently marketed in the United States.<br />
<br />
==606.2.2 Systematic Application of Median Guard Cable==<br />
<br />
Median guard cable is most effective when installed as a system-wide solution to address cross-median crash types. The benefits are severely limited if the cable is only used in spot locations in response to crashes at those locations.<br />
<br />
Additionally, when determining the most appropriate locations for guard cable application, the designation of a route (interstate, US highway, state route) should not be a primary consideration.<br />
<br />
A corridor should have similar geometry and traffic volume and the placement of guard cable on the corridor should have logical termini. Spot location installation of new median guard cable should be used sparingly only in unique situations.<br />
<br />
==606.2.3 Warrants==<br />
<br />
Analyses of cross-median crash history and traffic volume provide valuable information in determining the likelihood of future severe crashes on these routes. In order to prevent future fatalities and disabling injuries, it is important to focus safety efforts on locations that will benefit the most from safety countermeasures.<br />
<br />
'''606.2.3.1 Crash Data.''' Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route and, even more so, on those crashes resulting in fatalities and disabling injuries.<br />
<br />
It is important this data analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a simple query of cross-median crashes may include unwanted events and exclude necessary ones. Accuracy of these data is vital in decision-making.<br />
<br />
The data should be reviewed each year to validate priorities and identify any emerging cross-median safety concerns. A regular review of divided highway traffic volume and crashes will provide information to proactively address severe cross-median crashes.<br />
<br />
'''606.2.3.2 Traffic Volume.''' Recent research has connected traffic volume growth directly to cross-median crash events. As volume increases, the probability of a motorist crossing the median and hitting an oncoming vehicle also increases. Instead of relying solely on crash history, there is an opportunity to proactively address this crash type before the crashes occur by studying traffic volume patterns and installing a system of median guard cable on routes with sharply increasing volumes. <br />
<br />
'''606.2.3.3 [[231.1 Median Width|Median Width]].''' Recent national experience has shown that cross-median crashes occur on highways with median widths above MoDOT's initial 60 ft. threshold. No route will be excluded from analysis solely on the basis of median width. Divided highways with very wide medians are expected to have little or no cross-median crash history that effectly removes them from consideration for barrier installation.<br />
<br />
==606.2.4 Design and Installation Guidelines==<br />
===606.2.4.1 Lateral Placement in the Median===<br />
<br />
'''Dynamics of Cross-Median Crashes.''' When a vehicle leaves the roadway and enters the median, certain predictable dynamics occur. Vehicles may enter the median at a variety of speeds and angles but for the purposes of roadside safety research and testing, a 60 mph departure at a 20° or 25° angle is generally used.<br />
<br />
Upon departure, a vehicle will initially continue along its vertical trajectory. As the inslope falls away along the 25° vehicle path, the vehicle effectively becomes briefly airborne. When the vehicle's inertia can no longer overcome gravity, it lands and its suspension is deeply compressed. As the vehicle continues to travel through the median, the suspension rebounds and the bumper of the vehicle stays at a relatively constant height throughout the remainder of the errant journey.<br />
<br />
Every guard cable crash is slightly different because of a host of site-specific factors. In general, however, the front of the vehicle must engage at least two of the three or four cables present in order to be contained by the system. Given the dynamics described above, lateral placement of the cable can be grouped into two main categories: medians wider than 30 ft. and those narrower than 30 ft.<br />
[[image:606.2.4.1 Placement.jpg|600px|right]]<br />
'''Medians 30 ft. or wider.''' The guard cable should be installed 4 ft. downslope of the edge of the shoulder. Assuming a 4 ft. inside shoulder, this location would place the barrier 8 ft. from the edge of the traveled way. There are several advantages to this location but chief among them is the performance of the system in a crash. At the 4 ft. downslope location, the errant vehicle adjacent to the barrier, while airborne, is not at a great enough altitude to override the cable during a front side encounter. From the opposing direction, or backside, the suspension of the errant vehicle will have recovered enough to allow an impact to occur under relatively normal impact conditions.<br />
<br />
'''Medians narrower than 30 ft.''' In medians narrower than 30 ft., the guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. As previously discussed, this location performs the most advantageously. The 4 ft. downslope location starts to fail in narrower medians as the suspension of the vehicle impacting from the back side (i.e. the opposite direction) is the most tightly compressed around that location. Again, a fully compressed suspension has proven to be the principal reason for vehicles underriding the system.<br />
<br />
'''Alternating Sides.''' The designer may choose to alternate the sides of the median where the barrier is placed for the purpose of reducing any shy line issues or discomfort for motorists. The change should occur at natural breaks in the barrier such as emergency crossovers or median bridge columns.<br />
<br />
'''Lateral Placement of Low-tension Guard Cable.''' New installations of low-tension guard cable should be installed within 1 ft. of the vertex of either a V or flat-bottomed ditch. Retrofits should be located at the existing offset, provided the system is functioning well.<br />
<br />
===606.2.4.2 Parallel Installations===<br />
In-service experience with parallel installations has shown less than desirable results. The close proximity of each installation to traffic has caused an inordinately high incidence of nuisance hits resulting in higher than acceptable long-term maintenance costs. Vegetative maintenance is also a concern.<br />
<br />
Parallel installations of guard cable should not be used. Instead, designers should rely upon guard cable designed for the situation as a single run or consider a barrier system other than guard cable.<br />
<br />
===606.2.4.3 Post Spacing===<br />
While guard cable has been tested and approved with post spacing ranging from 6.5 to 32.5 ft., it is widely believed that the wider post spacing leads to greater deflections and an increased likelihood of vehicle penetration due to underride or traveling between the cables. For this reason, post spacing should not exceed the conventional limit of 20 ft. Additionally, increasing post spacing through horizontal curves increases the opportunity for the cable to assume a chord length if the posts are damaged. If enough posts are damages, the cable could project into the travelway on the inside of the curve.<br />
<br />
===606.2.4.4 Slopes===<br />
'''1V:6H (6:1) or Flatter Slopes.''' Guard cable, like most roadside hardware, is intended for use on slopes that are 1V:6H (6:1) or flatter. This requirement is based on both computer modeling and full-scale crash testing and represents sound theory. In practice, however, slopes as flat at 1V:6H are often the exception.<br />
<br />
'''Steeper Slopes.''' Three [[131.2 Proprietary Items and Public Interest Findings#131.2.1.1 Proprietary Items|proprietary]] high-tension systems are now approved for use one slopes with gradients between 1V:6H (6:1) and 1V:4H (4:1). Their use, while generally more expensive, represents the most cost-effective solution for shielding steeper slopes. Further, since three equivalent sources exist, there is not need to obtain a [[131.2 Proprietary Items and Public Interest Findings#131.2.1.2 Public Interest Findings|public interest finding]] for their use.<br />
<br />
===606.2.4.5 Vegetative Barrier===<br />
[[:Category:822 Roadside Vegetation Management|Vegetation control]] in the area between the cable and the passing lane must be addressed. Failure to provide some positive form of vegetation control will hinder the future maintenance of the system. Positive vegetation control measures may include [[:Category:821 Herbicides and Roadsides|herbicides]], a geotextile-aggregate strip or asphalt apron. The core team must consult with the local maintenance personnel to arrive at a vegetative control measure that is mutually agreeable.<br />
<br />
A district's decision to mow around the barrier must be approved by [http://wwwi/maintenance/ Central Office Maintenance]. Such mowing operations must be accomplished without impeding through traffic in any manner.<br />
[[image:606.2.4.6.jpg|right|275px|thumb|'''<center>Anchor Assembly</center>''']]<br />
Vegetation control may not be omitted from a project as a practical design or value engineering measure.<br />
<br />
===606.2.4.6 Termination at [[:Category:240 Maintenance and Emergency Crossovers|Emergency Crossovers]]===<br />
<br />
The design for guard cable termination as well as the grading for the crossover should be in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/60641.pdf Standard Plan 606.41, Sheet 7 of 7]. Refer to [[:Category:240 Maintenance and Emergency Crossovers#240.4 Guard Cable Termination at Emergency Crossovers|EPG 240.4 Guard Cable Termination at Emergency Crossovers]] for additional information.<br />
<br />
==606.2.5 Maintenance and Repair==<br />
<br />
Irrespective of routes treated, proper placement or system used, cable median barrier is only as functional as its ongoing maintenance and repair. Proper maintenance and incident repair will ensure that the system is always in a state of functionality to provide motorists a greater level of safety on Missouri highways.<br />
<br />
'''Routine Maintenance. ''' Outside of vegetation control, there is little routine maintenance required for a guard cable system. If pre-stressed cables are used for high-tension systems and compensators are properly compressed for low-tension systems, the tension in the cable should properly acclimate to any weather condition. The tension monitoring stage occurs during and shortly after construction.<br />
<br />
'''Cable Height. ''' The importance of cable height to properly capture and redirect errant vehicles has been demonstrated. Although cable height is relatively static in all systems, erosion under the barrier can sometimes cause a localized increase in height, resulting in possible underride.<br />
<br />
Maintenance personnel should be educated on the necessity of proper cable height and encouraged to identify and repair locations where erosion or the accumulation of silt have altered the relative cable height. <br />
<br />
'''Median Condition. ''' A secondary issue, closely related to incident repair, is the post-entry condition of the median. In addition to the repair of the roadside hardware, the median condition with respect to rutting, loss of vegetation and accident debris should be remedied following each accident. These incidental concerns could cause instability in the trajectory of future errant vehicles and could, at worst, result in a failure of the system.<br />
<br />
'''Low-Tension Cable Barrier Repair: On-Call Contract.''' Maintenance of low-tension cable barrier is vastly more complicated than that of a high-tension system. In fact, the complexity of the system coupled with the frequency of crash incidents, have traditionally resulted in the system’s maintenance being outsourced through on-call contracts.<br />
<br />
'''High-Tension Cable Barrier Repair: In-House.''' Equipment and hardware needs for the repair of high-tension, socketed guard cable are minimal and repairs can generally be accomplished in under an hour with two workers, some hand tools and a pickup truck.<br />
<br />
'''Response Time.''' Due to the importance of the median guard cable performing when needed, it is vital to quickly respond to repair needs. This will often necessitate an effort to identify cable hits as soon as possible after the incident and then respond with repair as quickly as possible.<br />
<br />
Refer to [[120.5 Roadside Features#120.5.1 Guard Cable|EPG 120.5.1 Guard Cable]] for regular inspection goals for interstate guard cable maintenance.<br />
<br />
==606.2.6 Maintenance Planning Guidelines for Guard Cable==<br />
<br />
'''Printable''' [[media:R227 - Guard Cables.pdf|'''Maintenance Planning Guideline for Guard Cable''']].<br />
<br />
Index of all [[:Category:170 Maintenance Activity Planning Guidelines#Index of Printable Planning Guides|Maintenance Planning Guidelines]].<br />
<br />
==606.2.7 Construction Inspection Guidelines for Guard Cable==<br />
<br />
'''For [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec 606.50.2]'''. The embankment slope between the shoulder and the guard cable should be 1V:6H (6:1) or flatter. If only one run of three-strand guard cable is installed in the median, the slope on both sides of the guard cable should be 1V:6H (6:1) or flatter. No exceptions should be allowed unless approved by the Central Office. This is essential for the guard cable to perform as designed. A steeper side approach slope may allow a passenger vehicle to duck under the guard cable and subsequently not be stopped. The embankment slope behind the guard cable is not critical (may be as steep as 1V:2H (2:1)) if another run of three-strand guard cable is installed on the other side of the median to protect crossovers from that direction of traffic or if adequate clear zone is provided in the other direction of traffic.<br />
<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" align="right" <br />
|+<br />
! style="background:#BEBEBE"|Sieve Size !! style="background:#BEBEBE"|Percent Passing by Weight (mass) <br />
|-<br />
|align="center"|3 in. (75mm)||align="center"| 100<br />
|-<br />
|align="center"|1 in. (25mm)|| align="center"|80<br />
|-<br />
|align="center"|No. 4 (4.75mm)|| align="center"|0-35<br />
|}<br />
'''Aggregate Bedding (for [http://www.modot.mo.gov/business/standards_and_specs/Sec0606.pdf Sec. 606.50.2.4])'''. Having a predominantly one-sized stone as a bedding material for guard cable, as currently specified in Sec 606.50.4, will act as marbles when a vehicle impacts the bedding material and will likely result in an impacting vehicle to dive under the cable system and continue across the median into the opposing traffic, thereby defeating the purpose of the guard cable system. This is elevated to even a larger safety issue where contractors have provided sand or gravel as the bedding material, which have a greater tendency to roll like marbles when impacted and increases the probability for a vehicle to dive beneath the barrier system. In the interim of getting a specification revision, existing jobs should be change ordered to a bedding material consisting of a uniform, angular graded material of a gradation similar to that shown below. Verification of the gradation should be accomplished by visual inspection, and when in suspect, a sieve analysis should be conducted.<br />
<br />
'''Delineators (for Sec. 606.50.2.5).''' All three-strand guard cable, regardless of the location of the guard cable, should be delineated, with delineator spacing, reflective sheeting and reflector colors in accordance with Sec 606.10.2.3.<br />
<br />
[[Category:606 Guardrail and Guard Cable]]</div>Jonesjbhttps://epg.modot.org/index.php?title=903.6_Warning_Signs&diff=28037903.6 Warning Signs2012-02-22T14:12:01Z<p>Jonesjb: Legal vehicle height in commercial zone corrected to 15 ft.</p>
<hr />
<div>{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W1-1.gif|left|150px]]<br />
||[[image:W1-8.gif|left|125px]]<br />
||[[image:W1-13.gif|left|150px]]<br />
|}<br />
<br />
==903.6.1 Function of Warning Signs (MUTCD Section 2C.01)==<br />
<br />
'''Support.''' Warning signs call attention to unexpected conditions on or adjacent to a highway, street or private road open to public travel and to situations that might not be readily apparent to road users. Warning signs alert road users to conditions that might call for a reduction of speed or an action in the interest of safety and efficient traffic operations.<br />
<br />
==903.6.2 Application of Warning Signs (MUTCD Section 2C.02)==<br />
<br />
'''Standard.''' The use of warning signs shall be based on an engineering study or on engineering judgment.<br />
<br />
'''Guidance.''' The use of warning signs should be kept to a minimum as the unnecessary use of warning signs tends to increase disrespect for all signs. In situations where the condition or activity is seasonal or temporary, the warning sign should be removed or covered when the condition or activity does not exist.<br />
<br />
'''Option.''' Consistent with the provisions of the EPG, [[616.3 Changeable Message Signs (CMS)|changeable message signs]] may be used to display a warning message. Consistent with the provisions of [[902.12 Flashing Beacons (MUTCD Chapter 4L)#902.12.3 Warning Beacon (MUTCD Section 4L.03)|EPG 902.12.3, a Warning Beacon]] may be used in combination with a standard warning sign.<br />
<br />
'''Support.''' The categories of Warning signs are shown in Table 903.6.2. Warning signs provided in [[:Category:903 Highway Signing|EPG 903]] cover most of the conditions that are likely to be encountered. Additional warning signs for temporary traffic control zones, school areas, grade crossings and bicycle facilities are discussed in [[616.2 Work Zone Signing and Applications#616.2.2 Warning Signs|EPG 616.2.2]], [[903.19 Signing for School Areas|EPG 903.19 Signing for School Areas]], [[903.20 Signing for Rail and Light Rail Transit Grade Crossings|EPG 903.20 Signing for Rail and Light Rail Transit Grade Crossings]] and [[903.21 Signing for Bicycle Facilities|EPG 903.21 Signing for Bicycle Facilities]].<br />
<br />
'''Option.''' Word message warning signs other than those specified in this article may be developed and installed.<br />
<br />
===<center>Table 903.6.2 Categories of Warning Signs and Plaques</center>=== <br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ <br />
! style="background:#BEBEBE" |Category!! style="background:#BEBEBE" |Group !! style="background:#BEBEBE" |EPG Article !! style="background:#BEBEBE" |Signs or Plaques!! style="background:#BEBEBE"|Sign Numbers<br />
|-<br />
!rowspan="19"|Roadway Related<br />
|rowspan="8"|Changes in Horizontal Alignment||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]]||Turn, Curve, Reverse Turn, Reverse Curve, Winding Road, Hairpin Curve||W1-1, 2, 3, 4, 5, 11, 15<br />
|-<br />
| [[#903.6.46 Advisory Speed Supplemental Plaque (W13-1P) (MUTCD Section 2C.08|903.6.46]]||Advisory Speed|| W13-1P<br />
|-<br />
|[[#903.6.11 Chevron Alignment Sign (W1-8) (MUTCD Section 2C.09)|903.6.11]] || Chevron Alignment|| W1-8<br />
|-<br />
|[[#903.6.8 Combination Horizontal Alignment/Advisory Speed Sign (W1-1a, W1-2a) (MUTCD Section 2C.10)|903.6.8]] ||Combination Horizontal Alignment/Advisory Speed ||W1-1a, 2a<br />
|-<br />
|[[#903.6.9 Combination Horizontal Alignment/Intersection Signs (W1-10 Series) (MUTCD Section 2C.11)|903.6.9]] ||Combination Horizontal Alignment/Intersection ||W1-10, 10a, 10b, 10c, 10d<br />
|-<br />
|[[#903.6.10 One-Direction Large Arrow Sign (W1-6) (MUTCD Section 2C.12)|903.6.10]] ||Large Arrow (one direction) ||W1-6<br />
|-<br />
|[[#903.6.12 Truck Rollover Warning Sign (W1-13) (MUTCD Section 2C.13)|903.6.12]] ||Truck Rollover ||W1-13<br />
|-<br />
|[[#903.6.36 Advisory Exit and Ramp Speed Signs (W13-2 and W13-3) (MUTCD Section 2C.14)|903.6.36]] ||Advisory Exit or Ramp Speed ||W13-2, 3<br />
|-<br />
|Vertical Alignment ||[[#903.6.13 Hill Signs (W7-1) (MUTCD Section 2C.16)|903.6.13]] ||Hill|| W7-1, 1a, 2P, 2bP, 3P, 3aP, 3bP<br />
|-<br />
|rowspan="5"|Cross-Section||[[#903.6.15 ROAD NARROWS Sign (W5-1) (MUTCD Section 2C.19)|903.6.15]] ||Road Narrows ||W5-1<br />
|-<br />
|[[#903.6.16 NARROW BRIDGE Sign (W5-2) (MUTCD Section 2C.20)|903.6.16]], [[#903.6.17 ONE LANE BRIDGE Sign (W5-3) (MUTCD Section 2C.21)|903.6.17]] ||Narrow Bridge, One Lane Bridge ||W5-2, 3<br />
|-<br />
|[[#903.6.18 Divided Highway Sign (W6-1) (MUTCD Section 2C.22)|903.6.18]] - [[#903.6.20 Double Arrow Sign (W12-1) (MUTCD Section 2C.20)|903.6.20]] ||Divided Highway, Divided Highway Ends, Double Arrow|| W6-1, 2; W12-1<br />
|-<br />
|[[#903.6.21 DEAD END, NO OUTLET and ROAD ENDS Signs (W14-1, W14-2, W14-13) (MUTCD Section 2C.21)|903.6.21]] ||Dead End, No Outlet ||W14-1, 1a, 2, 2a<br />
|-<br />
|[[#903.6.22 Low Clearance Sign (W12-2 and W12-2a) (MUTCD Section 2C.27)|903.6.22]] ||Low Clearance ||W12-2, 2a<br />
|-<br />
|rowspan="4"|Roadway Surface Condition|| [[#903.6.23 BUMP and DIP Signs (W8-1, W8-2) (MUTCD Section 2C.28)|903.6.23]] ||Bump, Dip ||W8-1, 2<br />
|-<br />
| [[#903.6.24 PAVEMENT ENDS Sign (W8-3) (MUTCD Section 2C.30)|903.6.24]] ||Pavement Ends ||W8-3<br />
|-<br />
| [[#903.6.25 SOFT SHOULDER Sign (W8-4) (MUTCD Section 2C.31)|903.6.25]] ||Soft Shoulder ||W8-4<br />
|-<br />
|[[#903.6.26 Slippery When Wet Sign (W8-5) (MUTCD Section 2C.32)|903.6.26]], [[#903.6.27 FALLEN ROCKS Sign (W8-14) (MUTCD Section 2C.32)|903.6.27]] ||Slippery When Wet, Fallen Rocks ||W8-5, 20<br />
|-<br />
|Weather || [[#903.6.52 IMPASSABLE DURING HIGH WATER Sign (W8-18, W8-19a, W8-34, W8-35) (MUTCD Section 2C.35)|903.6.52]] ||Road May Flood, Flood Gauge, Gusty Winds Area, Fog Area||W8-18, 19, 21, 22<br />
|-<br />
!rowspan="7"|Traffic Related <br />
||Advance Traffic Control||[[#903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)|903.6.28]] - [[#903.6.30 Reduced Speed Limit Ahead Signs (W3-5) (MUTCD Section 2C.38)|903.6.30]] ||Stop Ahead, Yield Ahead, Signal Ahead, Be Prepared To Stop, Speed Reduction, Ramp Meter Ahead|| W3-1, <br />
2, 3, 4, 5, 5a, 6, 7, 8<br />
|-<br />
|Traffic Flow || [[#903.6.31 Merge Signs (W4-1, W4-5) (MUTCD Section 2C.31)|903.6.31]] - [[#903.6.36 Advisory Exit and Ramp Speed Signs (W13-2 and W13-3) (MUTCD Section 2C.14)|903.6.36]] ||Merge, No Merge Area, Lane Ends, Added Lane, Two-Way Traffic, Right Lane Exit Only Ahead, No Passing Zone ||W4-1, 2, 3, 5, 5P, 6; W6-3;W9-1, 2, 7; W14-3<br />
|-<br />
|rowspan="3"|Intersections || [[#903.6.37 Intersection Warning Signs (W2-1 through W2-5) (MUTCD Section 2C.46)|903.6.37]] ||Crossroad, Side Road, T, Y, Circular Intersection, Side Roads|| W2-1, 2, 3, 4, 5, 6, 7, 8; W16-12P, 17P<br />
|-<br />
| [[#903.6.38 Two-Direction Large Arrow Sign (W1-7) (MUTCD Section 2C.47)|903.6.38]] ||Large Arrow (two direction) ||W1-7<br />
|-<br />
| [[#903.6.39 Traffic Signal Signs (W25-1, W25-2) (MUTCD Section 2C.48)|903.6.39]] ||Oncoming Extended Green ||W25-1, 2<br />
|-<br />
|Vehicular Traffic|| [[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]] ||Truck Crossing, Truck (symbol), Emergency Vehicle, Tractor, Bicycle, Golf Cart, Horse-Drawn Vehicle, Trail Crossing ||W8-6; W11-1, 5, 5a, 8, 10, 11, 12P, 14, 15, 15P, 15a; W16-13P<br />
|-<br />
|Non-Vehicular|| [[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||Pedestrian, Deer, Cattle, Snowmobile, Equestrian, Wheelchair, Large Animals, Playground ||W11-2, 3, 4, 6, 7, 9, 16, 17, 18, 19, 20, 21, 22; W15-1; W16-13P<br />
|-<br />
!rowspan="7"|Other Supplemental Plaques<br />
||Location|| [[#903.6.56 Warning Signs Provided for Other Agencies|903.6.56]] ||Downward Diagonal Arrow, Ahead|| W16-7P, 9P<br />
|-<br />
|Distance|| [[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|903.6.45]] ||XX Feet, XX Miles, Next XX Feet, Next XX Miles|| W7-3aP; W16-2P, 2aP, 3P, 3aP, 4P<br />
|-<br />
|Arrow || [[#903.6.47 Supplemental Arrow Plaque (W16-5P, W16-6P) (MUTCD Section 2C.56)|903.6.47]] ||Advance Arrow, Directional Arrow ||W16-5P, 6P<br />
|-<br />
|Street Name Plaque || [[#903.6.48 Advance Street Name Supplemental Plaque (W16-8P, W16-8aP) (MUTCD Section 2C.58)|903.6.48]] ||Advance Street Name ||W16-8P, 8aP<br />
|-<br />
|Intersection|| [[#903.6.49 CROSS TRAFFIC DOES NOT STOP Plaque (W4-4P) (MUTCD Section 2C.59)|903.6.49]] ||Cross Traffic Does Not Stop ||W4-4P, 4aP, 4bP<br />
|-<br />
|Share The Road|| [[#903.6.50 SHARE THE ROAD Supplemental Plaque (W16-1) (MUTCD Section 2C.51)|903.6.50]] ||Share The Road ||W16-1P<br />
|-<br />
|Photo Enforced|| [[#903.6.51 PHOTO ENFORCED Plaque (W16-10aP) (MUTCD Section 2C.61)|903.6.51]] ||Photo Enforced ||W16-10P, 10aP<br />
|}<br />
<br />
==903.6.3 Design of Warning Signs (MUTCD Section 2C.03)==<br />
<br />
'''Standard.''' Except as provided below or unless specifically designated otherwise, all warning signs shall be diamond-shaped (square with one diagonal vertical) with a black legend and border on a fluorescent yellow background. Warning signs shall be designed in accordance with the sizes, shapes, colors and legends contained in the ''Standard Highway Signs and Markings'' book. <br />
<br />
'''Option.''' A warning sign that is larger than the size shown in the Oversized column in Table 903.6.3 for that particular sign may be diamond-shaped or may be rectangular or square in shape. Warning signs regarding conditions associated with pedestrians, bicyclists and playgrounds may have a black legend and border on a fluorescent yellow background or a fluorescent yellow-green background. <br />
<br />
'''Standard.''' Warning signs regarding conditions associated with school buses and schools and their related supplemental plaques shall have a black legend and border on a fluorescent yellow-green background (see [[903.19 Signing for School Areas#903.19.9 School Zone Sign (S1-1) and Plaques (S4-3P) and END SCHOOL ZONE Sign (S5-2) (MUTCD Section 7B.09)|EPG 903.19.9]]).<br />
<br />
====<center>Table 903.6.3 Warning Sign and Plaque Sizes</center>====<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ <br />
! style="background:#BEBEBE" ROWSPAN="2"|Sign or Plaque!! style="background:#BEBEBE" ROWSPAN="2"|Sign Designation !! style="background:#BEBEBE" ROWSPAN="2"|EPG Article !! style="background:#BEBEBE" colspan="3"|Conventional Road (in. x in.)!! style="background:#BEBEBE"|Freeway/Expressway (in. x in.)<br />
|-<br />
! style="background:#BEBEBE"|Single Lane !! style="background:#BEBEBE"|Multi-Lane !! style="background:#BEBEBE"| Oversized !! style="background:#BEBEBE"|Mainline & Ramps<br />
|-<br />
! Turn<br />
||W1-1 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Curve<br />
||W1-2 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Reverse Turn <br />
||W1-3 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Reverse Curve <br />
||W1-4 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Winding Road<br />
||W1-5 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Hairpin Curve <br />
||W1-11 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!270° Curve<br />
||W1-15 ||[[#903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)|903.6.7]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Combination Turn/Advisory Speed<br />
||W1-1a ||[[#903.6.8 Combination Horizontal Alignment/Advisory Speed Sign (W1-1a, W1-2a) (MUTCD Section 2C.10)|903.6.8]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Combination Curve/Advisory Speed <br />
||W1-2a ||[[#903.6.8 Combination Horizontal Alignment/Advisory Speed Sign (W1-1a, W1-2a) (MUTCD Section 2C.10)|903.6.8]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Combination Horizontal Alignment/Intersection <br />
||W1-10 ||[[#903.6.9 Combination Horizontal Alignment/Intersection Signs (W1-10 Series) (MUTCD Section 2C.11)|903.6.9]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!One-Direction Large Arrow <br />
||W1-6 ||[[#903.6.10 One-Direction Large Arrow Sign (W1-6) (MUTCD Section 2C.12)|903.6.10]] ||48 X 24||48 X 24||72 X 36|| 72 X 36<br />
|-<br />
!Chevron<br />
||W1-8 ||[[#903.6.11 Chevron Alignment Sign (W1-8) (MUTCD Section 2C.09)|903.6.11]] ||18 X 24||18 X 24||30 X 36|| 30 X 36<br />
|-<br />
!Truck Rollover <br />
||W1-13 ||[[#903.6.12 Truck Rollover Warning Sign (W1-13) (MUTCD Section 2C.13)|903.6.12]] ||- ||- ||- ||48 X 48<br />
|-<br />
!Hill<br />
||W7-1 ||[[#903.6.13 Hill Signs (W7-1) (MUTCD Section 2C.16)|903.6.13]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!ROAD NARROWS<br />
||W5-1 ||[[#903.6.14 Hill-Related Supplemental Plaques (W7-3 Series) (MUTCD Section 2C.57)|903.6.14]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!NARROW BRIDGE<br />
||W5-2 ||[[#903.6.15 ROAD NARROWS Sign (W5-1) (MUTCD Section 2C.19)|903.6.15]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!ONE LANE BRIDGE<br />
||W5-3 ||[[#903.6.16 NARROW BRIDGE Sign (W5-2) (MUTCD Section 2C.20)|903.6.16]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Divided Highway<br />
||W6-1 ||[[#903.6.17 ONE LANE BRIDGE Sign (W5-3) (MUTCD Section 2C.21)|903.6.17]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Divided Highway Ends <br />
||W6-2 ||[[#903.6.18 Divided Highway Sign (W6-1) (MUTCD Section 2C.22)|903.6.18]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Double Down Arrow<br />
||W12-1 ||[[#903.6.19 Divided Highway Ends Sign (W6-2) (MUTCD Section 2C.23)|903.6.19]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!DEAD END<br />
||W14-1 || [[#903.6.20 Double Arrow Sign (W12-1) (MUTCD Section 2C.25)|903.6.20]] ||36 X 36||36 X 36||36 X 36|| 36 X 36<br />
|-<br />
!NO OUTLET<br />
||W14-2 ||[[#903.6.20 Double Arrow Sign (W12-1) (MUTCD Section 2C.25)|903.6.20]] ||36 X 36||36 X 36||36 X 36|| 36 X 36<br />
|-<br />
!ROAD ENDS<br />
||W14-13||[[#903.6.20 Double Arrow Sign (W12-1) (MUTCD Section 2C.25)|903.6.20]] ||36 X 36||36 X 36||36 X 36|| 36 X 36<br />
|-<br />
!Low Clearance<br />
||W12-2 ||[[#903.6.21 DEAD END, NO OUTLET and ROAD ENDS Signs (W14-1, W14-2, W14-13) (MUTCD Section 2C.21)|903.6.26]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!LOW CLEARNACE (overhead)<br />
||W12-2a||[[#903.6.21 DEAD END, NO OUTLET and ROAD ENDS Signs (W14-1, W14-2, W14-13) (MUTCD Section 2C.21)|903.6.26]] ||- ||- ||- ||84 X 24<br />
|-<br />
!PAVEMENT ENDS<br />
||W8-3 ||[[#903.6.24 PAVEMENT ENDS Sign (W8-3) (MUTCD Section 2C.30)|903.6.24]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!SOFT SHOULDER<br />
||W8-4 ||[[#903.6.25 SOFT SHOULDER Sign (W8-4) (MUTCD Section 2C.31)|903.6.25]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!FALLEN ROCK<br />
||W8-14 ||[[#903.6.27 FALLEN ROCKS Sign (W8-14) (MUTCD Section 2C.32)|903.6.27]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Stop Ahead<br />
||W3-1 ||[[#903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)|903.6.28]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Yield Ahead<br />
||W3-2 ||[[#903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)|903.6.28]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Signal Ahead<br />
||W3-3 ||[[#903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)|903.6.28]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!BE PREPARED TO STOP<br />
||W3-4 ||[[#903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)|903.6.28]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Ramp Meter Ahead<br />
||W3-7 || [[#903.6.29 Advance Ramp Control Signal Signs (W3-7 and W3-8) (MUTCD Section 2C.37)|903.6.29]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Ramp Meter When Flashing<br />
||W3-8 ||[[#903.6.29 Advance Ramp Control Signal Signs (W3-7 and W3-8) (MUTCD Section 2C.37)|903.6.29]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Reduced Speed Ahead <br />
||W3-5 ||[[#903.6.30 Reduced Speed Limit Ahead Signs (W3-5) (MUTCD Section 2C.38)|903.6.30]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Merge<br />
||W4-1 ||[[#903.6.31 Merge Signs (W4-1, W4-5) (MUTCD Section 2C.31)|903.6.40]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Entering Roadway Merge<br />
||W4-5 ||[[#903.6.31 Merge Signs (W4-1, W4-5) (MUTCD Section 2C.31)|903.6.40]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Added Lane<br />
||W4-3 || [[#903.6.32 Added Lane Signs (W4-3, W4-6) (MUTCD Section 2C.41)|903.6.32]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Entering Roadway Added Lane<br />
||W4-6 ||[[#903.6.32 Added Lane Signs (W4-3, W4-6) (MUTCD Section 2C.41)|903.6.32]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Lane Ends<br />
||W4-2 || [[#903.6.33 LANE END Signs (W4-2, W9-1, W9-2) (MUTCD Section 2C.42)|903.6.33]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Left (Right) Lane Ends<br />
||W9-1 ||[[#903.6.33 LANE END Signs (W4-2, W9-1, W9-2) (MUTCD Section 2C.42)|903.6.33]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Lane Ends Merge Left (Right) <br />
||W9-2 ||[[#903.6.33 LANE END Signs (W4-2, W9-1, W9-2) (MUTCD Section 2C.42)|903.6.33]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Two-Way Traffic<br />
||W6-3 ||[[#903.6.34 Two-Way Traffic Sign (W6-3, W16-9P) (MUTCD Section 2C.44)|903.6.34]] ||36 X 36||36 X 36||48 X 48||48 X 48<br />
|-<br />
!NO PASSING ZONE (pennant)<br />
||W14-3 || [[#903.6.35 NO PASSING ZONE Sign (W14-3) (MUTCD Section 2C.45)|903.6.35]] ||48 X 30 ||- ||- ||-<br />
|-<br />
!Advisory Exit Speed <br />
||W13-2 ||[[#903.6.36 Advisory Exit and Ramp Speed Signs (W13-2 and W13-3) (MUTCD Section 2C.14)|903.6.36]] ||- ||- ||- ||48 X 60<br />
|-<br />
!Advisory Ramp Speed <br />
||W13-3 ||[[#903.6.36 Advisory Exit and Ramp Speed Signs (W13-2 and W13-3) (MUTCD Section 2C.14)|903.6.36]] ||- ||- ||- ||48 X 60<br />
|-<br />
!Crossroad<br />
||W2-1 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Side Road<br />
||W2-2 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Side Road (45°)<br />
||W2-3 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!T Intersection <br />
||W2-4 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Y Intersection<br />
||W2-5 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Circular Intersection <br />
||W2-6 ||[[#903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)|903.6.37]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Two-Direction Large Arrow<br />
||W1-7 ||[[#903.6.38 Two-Direction Large Arrow Sign (W1-7) (MUTCD Section 2C.47)|903.6.38]] ||48 X 24||48 X 24||72 X 36|| 72 X 36<br />
|-<br />
!TRAFFIC SIGNAL HAS EXTENDED GREEN<br />
||W25-1 ||[[#903.6.39 Traffic Signal Signs (W25-1, W25-2) (MUTCD Section 2C.48)|903.6.39]] ||24 X 30||24 X 30|| -|| -<br />
|-<br />
!TRAFFIC SIGNAL MAY HAVE EXTENDED GREEN<br />
||W25-2 ||[[#903.6.39 Traffic Signal Signs (W25-1, W25-2) (MUTCD Section 2C.48)|903.6.39]] ||24 X 30||24 X 30|| -|| -<br />
|-<br />
!Bicycle<br />
||W11-1 ||[[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Farm Vehicle<br />
||W11-5 ||[[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Emergency Vehicle<br />
||W11-8 ||[[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Truck <br />
||W11-10|| [[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]]||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Horse-Drawn Vehicle <br />
||W11-14||[[#903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)|903.6.40]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Pedestrian<br />
||W11-2 ||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||48 x 48||48 X 48|| -<br />
|-<br />
!Downward Diagonal Arrow<br />
||W16-7P||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!Deer <br />
||W11-3 ||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Cattle <br />
||W11-4 ||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Equestrian<br />
||W11-7 ||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Duck <br />
||W11-32||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!Pedestrian on Bridge <br />
||W11-33||[[#903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)|903.6.41]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!FERRY CROSSING AHEAD<br />
||W3-10 ||[[#903.6.42 FERRY CROSSING AHEAD Sign (W3-18)|903.6.42]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!_ FEET<br />
||W16-2P||[[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|903.6.45]] ||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!_ MILES<br />
||W16-3P|| [[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|903.6.45]]||30 X 24||30 X 24||30 X 24|| 30 X 24<br />
|-<br />
!NEXT _ FEET<br />
||W16-4P|| [[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|903.6.45]]||30 X 24||30 X 24||30 X 24|| 30 X 24<br />
|-<br />
!NEXT _ FEET<br />
||W7-3a ||[[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|903.6.45]] ||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!Advisory Speed<br />
||W13-1P||[[#903.6.46 Advisory Speed Supplemental Plaque (W13-1P) (MUTCD Section 2C.08)|903.6.46]]||24 X 24||24 X 24||30 X 30|| 30 X 30<br />
|-<br />
!Directional Arrow<br />
||W16-5P|| [[#903.6.47 Supplemental Arrow Plaque (W16-5P, W16-6P) (MUTCD Section 2C.56)|903.6.47]]||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!Advance Turn Arrow<br />
||W16-6P||[[#903.6.47 Supplemental Arrow Plaque (W16-5P, W16-6P) (MUTCD Section 2C.56)|903.6.47]] ||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!Percent Grade <br />
||W7-3P ||[[#903.6.48 Advance Street Name Supplemental Plaque (W16-8P, W16-8aP) (MUTCD Section 2C.58)|903.6.48]] ||24 X 18||24 X 18||30 X 24|| 30 X 24<br />
|-<br />
!Advance Street Name<br />
||W16-8P|| [[#903.6.49 CROSS TRAFFIC DOES NOT STOP Plaque (W4-4P) (MUTCD Section 2C.59)|903.6.49]]||Varies X 15||Varies X 15||Varies X 15|| Varies X 15<br />
|-<br />
!CROSS TRAFFIC DOES NOT STOP<br />
||W4-4P || [[#903.6.50 SHARE THE ROAD Supplemental Plaque (W16-1P) (MUTCD Section 2C.60)|903.6.50]] ||36 X 18||36 X 18||36 X 18|| 36 X 18<br />
|-<br />
!SHARE THE ROAD<br />
||W16-1P|| [[#903.6.51 PHOTO ENFORCED Plaque (W16-10aP) (MUTCD Section 2C.61)|903.6.51]] ||24 X 30||24 X 30|| -|| 24 X 30<br />
|-<br />
!PHOTO ENFORCED<br />
||W16-10aP|| [[#903.6.52 IMPASSABLE DURING HIGH WATER Sign (W8-18, W8-19a, W8-34, W8-35) (MUTCD Section 2C.35)|903.6.52]]||36 X 24||36 X 24|| -|| -<br />
|-<br />
!WATER OVER ROAD<br />
||W8-33 || [[#903.6.53 Hazard Communication Signs|903.6.53]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!IMPASSABLE DURING HIGH WATER<br />
||W8-34 || [[#903.6.53 Hazard Communication Signs|903.6.53]] ||36 X 36||36 X 36||48 X 48|| 48 X 48<br />
|-<br />
!LOW WATER CROSSING<br />
||W8-35 || [[#903.6.53 Hazard Communication Signs|903.6.53]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!Water Gauge<br />
||W8-19a|| [[#903.6.53 Hazard Communication Signs|903.6.53]]||9 X 48||9 X 48|| -|| -<br />
|-<br />
!Passing Lane<br />
||W6-6a || [[#903.6.57 Passing Lane Warning Signs (W6-6a, W6-6aP, W6-16, W6-17)|903.6.57]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!PASSING LANE<br />
||W6-6aP|| [[#903.6.57 Passing Lane Warning Signs (W6-6a, W6-6aP, W6-16, W6-17)|903.6.57]]||42 X 12||42 X 12|| -|| -<br />
|-<br />
!PASSING LANE ENDS<br />
||W6-16 || [[#903.6.57 Passing Lane Warning Signs (W6-6a, W6-6aP, W6-16, W6-17)|903.6.57]] ||36 X 36||36 X 36|| -|| -<br />
|-<br />
!WATCH FOR LEFT-TURNING TRAFFIC IN PASSING LANE<br />
||W6-17 || [[#903.6.57 Passing Lane Warning Signs (W6-6a, W6-6aP, W6-16, W6-17)|903.6.57]] ||72 X 48||72 X 48|| -|| -<br />
|-<br />
!TRAVEL SAFE ZONE<br />
||W26-1 || [[#903.6.58 TRAVEL SAFE ZONE – FINES DOUBLED Sign (W26-1)|903.6.58]] ||36 X 48||36 X 48||48 X 60|| 48 X 60<br />
|}<br />
<br />
==903.6.4 Size of Warning Signs (MUTCD Section 2C.04)==<br />
<br />
'''Standard.''' Except as provided in [[903.2 Extent of Signing#903.2.21 Dimensions (MUTCD Section 2A.11)|EPG 903.2.21]], the sizes for warning plaques shall be as shown in Table 903.6.4. Except as provided below, the minimum size for all diamond-shaped warning signs facing traffic on a multi-lane conventional road where the posted speed limit is higher than 35 mph shall be 36 in. x 36 inches. <br />
<br />
===<center>Table 903.6.4, Minimum Size of Supplemental Warning Plaques===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+<br />
! style="background:#BEBEBE" rowspan="3"|Size of Warning Sign (in. x in.)!! style="background:#BEBEBE" colspan="4"|Size of Supplemental Plaque (in. x in.)<br />
|-<br />
! style="background:#BEBEBE" colspan="3"|Rectangular !! style="background:#BEBEBE" rowspan="2"|Square<br />
|-<br />
! style="background:#BEBEBE"|1 Line !! style="background:#BEBEBE"|2 Lines !! style="background:#BEBEBE"|Arrow<br />
|-<br />
|24 X 24||rowspan="2"| 24 X 12||rowspan="2"| 24 X 18 ||rowspan="2"|24 X 12|| rowspan="2"|18 X 18<br />
|-<br />
|30 X 30 <br />
|-<br />
|36 X 36||rowspan="2"| 30 X18 ||rowspan="2"|30 X 24|| rowspan="2"|30 X 18||rowspan="2"|24 X 24<br />
|-<br />
|48 X 48 <br />
|} <br />
<br />
</center><br />
'''Option.''' The smaller signs may be used on low-speed roadways where the reduced legend size would be adequate for the warning or where physical conditions preclude the use of the other sizes. <br />
<br />
Larger sizes may be used for those special applications where speed, volume or other factors result in conditions where increased emphasis, improved recognition or increased legibility would be desirable. <br />
<br />
Signs larger than those shown in Table 903.6.3 may be used with the approval of the State Traffic Engineer. <br />
<br />
'''Guidance.''' The minimum size for all diamond-shaped warning signs facing traffic on exit and entrance ramps should be the same size sign as the mainline roadway classification.<br />
<br />
==903.6.5 Sight Distance==<br />
<br />
'''Support.''' The decision to use most warning signs is based on prevailing conditions. The items to be considered when determining the need for a warning sign are sight distance and prevailing speed. Prevailing speed is determined by using either the posted or 85<sup>th</sup> percentile speed on the facility. Sight distance is the distance a driver requires to perceive, react and respond to a condition. The prevailing speed affects the amount of sight distance required for a condition.<br />
<br />
It is a recommended to use Table 903.6.5 to determine the sight distance needed when considering the use of most warning signs. If the sight distance is less than that in Table 903.6.5, a sign may be needed.<br />
<br />
===<center>Table 903.6.5 Sight Distance Requirments</center>===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
! style="background:#BEBEBE"|Prevailing Speed (mph) !! style="background:#BEBEBE"|Distance (ft.)<br />
|-<br />
| align="center"|30|| align="center"| 200<br />
|-<br />
| align="center"|35 || align="center"|250<br />
|-<br />
| align="center"|40|| align="center"| 305<br />
|-<br />
| align="center"|45|| align="center"| 360<br />
|-<br />
| align="center"|50|| align="center"| 425<br />
|-<br />
| align="center"|55|| align="center"| 495<br />
|-<br />
| align="center"|60|| align="center"| 570<br />
|-<br />
| align="center"|65|| align="center"| 645<br />
|-<br />
| align="center"|70|| align="center"| 730<br />
|-<br />
|colspan="2"|Note: Based on the AASHTO Green Book, 2001 Edition, Exhibit 3-1<br />
|}<br />
<br />
==903.6.6 Placement of Warning Signs (MUTCD Section 2C.05)==<br />
<br />
'''Support.''' For information on placement of warning signs, see [[903.3 Post-Mounted Signing|EPG 903.3]] and [[903.4 Overhead Guide Sign Mounting|EPG 903.4]]. <br />
<br />
The time needed for detection, recognition, decision, and reaction is called the Perception-Response Time (PRT). <br />
<br />
Table 903.6.6 is provided as an aid for determining warning sign location. The distances shown in Table 903.6.6 can be adjusted for roadway features, other signing and to improve visibility.<br />
<br />
'''Standard.''' The minimum visibility for warning signs shall be determined from Table 903.6.6. <br />
<br />
'''Guidance.''' Warning signs should be placed so that they provide an adequate PRT. The distances contained in Table 903.6.6 are for guidance purposes and should be applied with engineering judgment. Warning signs are not to be placed so far in advance of the condition that drivers tend to forget the warning because of other driving distractions, especially in urban areas. <br />
<br />
Minimum spacing between warning signs with different messages should be based on the estimated PRT for driver comprehension of and reaction to the second sign. If an adjustment is necessary, every effort should be made to make it as small as possible. <br />
<br />
The effectiveness of the placement of warning signs should be periodically evaluated under both day and night conditions. <br />
<br />
'''Option.''' The values in Table 903.6.6 can be increased to provide this sign visibility based on field conditions and engineering judgment. <br />
<br />
Warning signs that advise road users about conditions that are not related to a specific location, such as Non-Vehicle signs or SOFT SHOULDER, may be installed in an appropriate location, based on engineering judgment, since they are not covered in Table 903.6.6.<br />
<br />
===<center>Table 903.6.6 Guidelines for Advance Placement of Warning Sign</center>===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
!style="background:#BEBEBE" rowspan="3"|Posted or 85th Percentile Speed !! style="background:#BEBEBE" colspan="9"|Advance Placement Distance<sup>1</sup> <br />
|-<br />
!style="background:#BEBEBE" rowspan="2"|Condition A: Speed reduction and lane changing in heavy traffic<sup>2!!style="background:#BEBEBE" colspan="8"|Condition B: Deceleration to the listed advisory speed (mph) for the condition<br />
|-<br />
!0<sup>3!!10<sup>4!!20<sup>4!!30<sup>4!!40<sup>4!!50<sup>4!!60<sup>4!!70<sup>4<br />
|-<br />
| align="center"|20 mph|| align="center"|225 ft.|| 100 ft.<sup>6||N/A<sup>5|| - ||-||-||-||-||-<br />
|-<br />
| align="center"|25 mph|| align="center"|325 ft.|| 100 ft.<sup>6||N/A<sup>5|| N/A<sup>5 ||-||-||-||-||-<br />
|-<br />
| align="center"|30 mph|| align="center"|460 ft.|| 100 ft.<sup>6||N/A<sup>5|| N/A<sup>5 ||-||-||-||-||-<br />
|-<br />
| align="center"|35 mph|| align="center"|565 ft.|| 100 ft.<sup>6||N/A<sup>5|| N/A<sup>5 ||N/A<sup>5||-||-||-||-<br />
|-<br />
| align="center"|40 mph|| align="center"|670 ft.|| 125 ft.||100 ft.<sup>6|| 100 ft.<sup>6 ||N/A<sup>5||-||-||-||-<br />
|-<br />
| align="center"|45 mph|| align="center"|775 ft.|| 175 ft.||125 ft.|| 100 ft.<sup>6 ||100 ft.<sup>6||N/A<sup>5||-||-||-<br />
|-<br />
| align="center"|50 mph|| align="center"|885 ft.|| 250 ft.||200 ft.||175 ft. ||125 ft.||100 ft.<sup>6||-||-||-<br />
|-<br />
| align="center"|55 mph|| align="center"|990 ft.|| 325 ft.||275 ft.||225 ft. ||200 ft.||125 ft.||N/A<sup>5||-||-<br />
|-<br />
| align="center"|60 mph|| align="center"|1100 ft.|| 400 ft.||350 ft.||325 ft. ||275 ft.||200 ft.||100 ft.<sup>6||-||-<br />
|-<br />
| align="center"|65 mph|| align="center"|1200 ft.|| 475 ft.||450 ft.||400 ft. ||350 ft.||275 ft.||200 ft.||100 ft.<sup>6||-<br />
|-<br />
| align="center"|70 mph|| align="center"|1250 ft.|| 550 ft.||525 ft.||500 ft. ||450 ft.||375 ft.||275 ft.||150 ft.||-<br />
|-<br />
| align="center"|75 mph|| align="center"|1350 ft.|| 650 ft.||625 ft.||600 ft. ||550 ft.||475 ft.||375 ft.||250 ft.||100 ft.<sup>6<br />
|-<br />
|colspan="10"|Notes:<br />
<br />
'''1''' The distances are adjusted for a sign legibility distance of 180 ft. for Condition A. The distances for Condition B have been adjusted for a sign legibility distance of 250 ft., which is appropriate for an alignment warning symbol sign. For Conditions A and B, warning signs with less than 6 in. legend or more than four words, a minimum of 100 ft. should be added to the advance placement distance to provide adequate legibility of the warning sign.<br />
<br />
'''2''' Typical conditions are locations where the road user must use extra time to adjust speed and change lanes in heavy traffic because of a complex driving situation. Typical signs are Merge and Right Lane Ends. The distances are determined by providing the driver a PRT of 14.0 to 14.5 seconds for vehicle maneuvers (2005 AASHTO Policy, Exhibit 3-3, Decision Sight Distance, Avoidance Maneuver E) minus the legibility distance of 180 ft. for the appropriate sign.<br />
<br />
'''3''' Typical condition is the warning of a potential stop situation. Typical signs are Stop Ahead, Yield Ahead, Signal Ahead, and Intersection Warning signs. The distances are based on the 2004 AASHTO Policy, Exhibit 3-1, Stopping Sight Distance, providing a PRT of 2.5 seconds, a deceleration rate of 11.2 ft./sec<sup>2</sup>, minus the sign legibility distance of 180 feet.<br />
<br />
'''4''' Typical conditions are locations where the road user must decrease speed to maneuver through the warned condition. Typical signs are Turn, Curve, Reverse Turn, or Reverse Curve. The distance is determined by providing a 2.5 second PRT, a vehicle deceleration rate of 10 ft./sec<sup>2</sup>, minus the sign legibility distance of 250 feet.<br />
<br />
'''5''' No suggested distances are provided for these speeds, as the placement location is dependent on site conditions and other signing. An alignment warning sign may be placed anywhere from the point of curvature up to 100 ft. in advance of the curve. However, the alignment warning sign should be installed in advance of the curve and at least 100 ft. from any signs.<br />
<br />
'''6''' The minimum advance placement distance is listed as 100 ft. to provide adequate spacing between signs.<br />
|}<br />
<br />
==903.6.7 Horizontal Alignment Signs (W1-1 through W1-5, W1-11) (MUTCD Section 2C.07)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W1-1.gif|left|thumb|<center>'''W1-1'''</center>|75px]]<br />
||[[image:W1-2.jpg|left|75px|thumb|<center>'''W1-2'''</center>]]<br />
||[[image:W1-3.jpg|left|75px|thumb|<center>'''W1-3'''</center>]]<br />
||[[image:W1-4.jpg|left|75px|thumb|<center>'''W1-4'''</center>]]<br />
||[[image:W1-5.gif|left|75px|thumb|<center>'''W1-5'''</center>]]<br />
||[[image:W1-11.gif|left|75px|thumb|<center>'''W1-11'''</center>]]<br />
||[[image:W1-15.jpg|left|75px|thumb|<center>'''W1-15'''</center>]]<br />
|}<br />
<br />
'''Support.''' A variety of horizontal alignment warning signs, pavement markings, and delineation can be used to advise motorists of a change in the roadway alignment. Uniform application of these traffic control devices with respect to the amount of change in the roadway alignment conveys a consistent message establishing driver expectancy and promoting effective roadway operations. The design and application of horizontal alignment warning signs to meet those requirements are addressed in EPG 903.6.7.1 through 903.6.7.4.<br />
<br />
===903.6.7.1 Turn and Curve Signs (W1-1, W1-2)===<br />
<br />
'''Standard.''' A Curve sign (W1-2) shall be used when the difference between the speed limit and advisory speed is 5 mph or greater, unless a different sign is recommended or allowed. A Turn sign (W1-1) shall be used instead of a Curve sign in advance of curves that have advisory speeds of 30 mph or less.<br />
<br />
===903.6.7.2 Reverse Turn and Reverse Curve Signs (W1-3, W1-4)===<br />
<br />
'''Guidance.''' Where there are two changes in roadway alignment in opposite directions that are separated by a tangent distance of less than 600 ft., the Reverse Turn (W1-3) sign should be used instead of multiple Turn (W1-1) signs and the Reverse Curve (W1-4) sign should be used instead of multiple Curve (W1-2) signs.<br />
<br />
===903.6.7.3 Winding Road Sign (W1-5)===<br />
<br />
'''Option.''' A Winding Road (W1-5) sign may be used instead of multiple Turn (W1-1) or Curve (W1-2) signs where there are three or more changes in roadway alignment each separated by a tangent distance of less than 600 feet.<br />
<br />
A NEXT XX MILES (W7-3aP) supplemental distance plaque may be installed below the Winding Road sign where continuous roadway curves exist for a specific distance.<br />
<br />
===903.6.7.4 Hairpin Curve (W1-11) and 270-Loop Signs (W1-15)===<br />
<br />
'''Option.''' If the curve has a change in horizontal alignment of 135 degrees or more, the Hairpin Curve (W1-11) sign may be used instead of a Curve or Turn sign.<br />
<br />
If the curve has a change of direction of approximately 270 degrees, such as on a cloverleaf interchange ramp, the 270-degree Loop (W1-15) sign may be used instead of a Curve or Turn sign.<br />
Guidance. When the Hairpin Curve sign or the 270-degree Loop sign is installed, either a One-Direction Large Arrow (W1-6) sign or Chevron Alignment (W1-8) signs should be installed on the outside of the turn or curve.<br />
<br />
===<center>Table 903.6.7 Horizontal Alignment Sign Usage</center>===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ <br />
!style="background:#BEBEBE" rowspan="2"|Number of Alignment Changes !! style="background:#BEBEBE" colspan="2"|Advisory Speed<br />
|-<br />
!style="background:#BEBEBE"|Less than or equal to 30 mph!!style="background:#BEBEBE"|Greater than 30 mph<br />
|-<br />
| align="center"|1|| align="center"|Turn (W1-1)<sup>1|| align="center"|Curve (W1-2)<sup>1<br />
|-<br />
| align="center"|2<sup>2|| align="center"|Reverse Turn (W1-3)<sup>3|| align="center"|Reverse Curve (W1-4)<sup>3<br />
|-<br />
| align="center"|3 or more<sup>2||colspan="2" align="center"|Winding Road (W1-5)<sup>3<br />
|-<br />
|colspan="3"|Notes:<br />
<br />
<sup>1</sup> Engineering judgment should be used to determine whether the Turn or Curve sign should be used.<br />
<br />
<sup>2</sup> Alignment changes are in opposite directions and are separated by a tangent distance of 600 ft. or less.<br />
<br />
<sup>3</sup> A Right Reverse Turn (W1-3R), Right Reverse Curve (W1-4R) or Right Winding (W1-5R) sign is used if the first change in aligment is the right; a Left Reverse Turn (W1-3L), Left Reverse Curve (W1-4L) or Left Winding (W1-5L) sign is used if the first change in aligment is the left.<br />
|}<br />
<br />
[[image:Figure 903.6.7.1.jpg|center|650px|thumb|'''Figure 903.6.7.1 Example For Placement of Curve Warning Sign, Condition B: Speed Plaque at 40 and Posted Speed at 50 mph''']]<br />
<br />
[[image:Figure 903.6.7.2.jpg|center|650px|thumb|'''Figure 903.6.7.2 Winding Road Distance Plaque Application''']]<br />
<br />
==903.6.8 Combination Horizontal Alignment/Advisory Speed Sign (W1-1a, W1-2a) (MUTCD Section 2C.10)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W1-1a.gif|left|thumb|<center>'''W1-1a'''</center>|100px]]<br />
||[[image:W1-2a.jpg|left|100px|thumb|<center>'''W1-2a'''</center>]]<br />
|}<br />
<br />
'''Option.''' The Turn (W1-1) sign or the Curve (W1-2) sign may be combined with the Advisory Speed (W13-1P) plaque (see [[#903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)|EPG 903.6.45]]) to create a combination Turn/Advisory Speed (W1-1a) sign, or combination Curve/Advisory Speed (W1-2a) sign.<br />
<br />
The combination Horizontal Alignment/Advisory Speed sign may be used to supplement the advance Horizontal Alignment warning sign and Advisory Speed plaque based upon an engineering study. <br />
<br />
'''Standard.''' If used, the combination Horizontal Alignment/Advisory Speed sign shall not be used alone and shall not be used as a substitute for a Horizontal Alignment warning sign and Advisory Speed sign shall only be used as a supplement to the advance Horizontal Alignment warning sign. If used, the combination Horizontal Alignment/Advisory Speed sign shall be installed at the beginning of the turn or curve and the speed displayed shall match the advisory speed below the Horizontal Alignment sign.<br />
<br />
'''Guidance.''' If used, the advisory speed displayed on the combination Horizontal Alignment/Advisory Speed sign should be based on the advisory speed for the horizontal curve using recommended engineering practices.<br />
<br />
==903.6.9 Combination Horizontal Alignment/Intersection Signs (W1-10 Series) (MUTCD Section 2C.11)==<br />
<br />
[[image:W1-10.gif|center|125px|thumb|<center>'''W1-10'''</center>]]<br />
<br />
'''Option.''' The Turn (W1-1) sign or the Curve (W1-2) sign may be combined with the Cross Road (W2-1) sign or the Side Road (W2-2 or W2-3) sign to create a combination Horizontal Alignment/Intersection (W1-10 series) sign that depicts the condition where an intersection occurs within or immediately adjacent to a turn or curve. <br />
<br />
'''Guidance.''' Elements of the combination Horizontal Alignment/Intersection sign related to horizontal alignment should comply with the provisions of EPG 903.6.7, Horizontal Alignment Sign, and elements related to intersection configuration should comply with the provisions of [[#903.6.35 NO PASSING ZONE Sign (W14-3) (MUTCD Section 2C.45)|EPG 903.6.35]], Intersection Warning Signs. The symbol design should approximate the configuration of the intersecting roadway(s). No more than one Cross Road or two Side Road symbols should be displayed on any one combination Horizontal Alignment/Intersection sign. <br />
<br />
A layout of the proposed sign should be included when ordering. <br />
<br />
'''Standard.''' If used, a Curve/Sideroad Left (W1-10L) sign shall indicate a curve to the left, while a Curve/Sideroad Right (W1-10R) sign shall indicate a curve to the right.<br />
<br />
==903.6.10 One-Direction Large Arrow Sign (W1-6) (MUTCD Section 2C.12)==<br />
[[image:W1-6.gif|center|125px|thumb|<center>'''W1-6'''</center>]]<br />
<br />
'''Option.''' A One-Direction Large Arrow (W1-6) sign may be used to either as a supplement or alternative to Chevron Alignment signs in order to delineate a change in horizontal alignment. A One-Direction Large Arrow (W1-6) sign may be used to supplement a Turn or Reverse Turn sign to emphasize the abrupt curvature (see Fig. 903.6.10).<br />
<br />
'''Standard.''' The One-Direction Large Arrow sign shall be a horizontal rectangle with an arrow pointing to the left or right. The use of the One-Direction Large Arrow sign shall be in accordance with the information shown in Table 903.6.7. If used, the One-Direction Large Arrow sign shall be installed on the outside of a turn or curve in line with and at approximately a right angle to approaching traffic. The One-Direction Large Arrow sign shall not be used where there is no alignment change in the direction of travel, such as at the beginnings and ends of medians or at center piers. The One-Direction Large Arrow sign directing traffic to the right shall not be used in the central island of a roundabout.<br />
<br />
'''Guidance.''' If used, the One-Direction Large Arrow sign should be visible for a sufficient distance to provide the road user with adequate time to react to the change in alignment. <br />
If chevrons are used, the One-Direction Large Arrow can replace a chevron. The One-Direction Large Arrow is not to be installed in front of a chevron. <br />
<br />
'''Support.''' The One-Direction Large Arrow is generally used in conjunction with the Turn sign.<br />
<br />
[[image:903.6.10.jpg|center|600px|thumb|<center>'''Figure 903.6.10 One-Direction Large Arrow Board'''</center>]]<br />
<br />
<br />
==903.6.11 Chevron Alignment Sign (W1-8) (MUTCD Section 2C.09)==<br />
<br />
[[image:W1-8.gif|center|125px|thumb|<center>'''W1-8'''</center>]]<br />
<br />
'''Standard.''' The use of the Chevron Alignment (W1-8) sign to provide additional emphasis and guidance for a change in horizontal alignment shall be in accordance with the information shown in Table 903.6.7. <br />
<br />
'''Option.''' When used, Chevron Alignment signs may be used instead of or in addition to standard delineators on curves or to the One-Direction Large Arrow (W1-6) sign. <br />
<br />
The single-sided Chevron sign side may be used where only one direction of travel is impacted, such as on an expressway. <br />
<br />
The double-side Chevron (W1-8D) may be used on two-lane, two-way roads. <br />
<br />
A Chevron Alignment sign may be used on the far side of an intersection to inform drivers of a change of horizontal alignment for through traffic.<br />
<br />
'''Standard.''' The Chevron Alignment sign shall be a vertical rectangle. No border shall be used on the Chevron Alignment sign. If used, Chevron Alignment signs shall be installed on the outside of a turn or curve, in line with and at approximately a right angle to approaching traffic. Chevron Alignment signs shall be installed at a minimum height of 5 ft., measured vertically from the bottom of the sign to the elevation of the near edge of the traveled way. <br />
<br />
This will place the sign at approximately the driver’s eye height. <br />
<br />
'''Guidance.''' The approximate spacing of Chevron Alignment signs on the turn or curve measured from the point of curvature (PC) should be as shown in Table 903.6.11. If used, Chevron Alignment signs should be visible for a sufficient distance to provide the road user with adequate time to react to the change in alignment. <br />
<br />
Table 903.6.11 should be used for determining spacing or refer to the Traffic Studies for Chord Method (see [[905.1 Traffic Data Collection#905.1.2.6 Measuring Degree of Curvature|EPG 905.1.2.6]]). The values in Table 903.6.11 are typical and variances for driveways, public roads and other signs may alter the spacing. Engineering judgment may be used to modify the spacing.<br />
<br />
At the end of a divided highway, where the traffic reduces to two lanes, chevrons should be used to direct traffic from the dual lanes that are ending and being redirected to the two-lane roadway. <br />
<br />
Space Chevron Alignment signs so that travelers always have at least two in view, until the change in alignment eliminates the need for the signs. Chevron Alignment signs should be visible for a sufficient distance to provide the road user with adequate time to react to the change in alignment.<br />
<br />
'''Support.''' To meet MoDOT’s Chevron Initiative, all horizontal curves shall comply with the following guidance. Examples of when to use Chevron signs include locations where there is an accident history, evidence of drivers losing control on a curve or turn or a sharp change in alignment not readily visible to the driver. <br />
<br />
'''Standard.''' Chevrons shall be placed on all curves where the there is a 15 mph difference between the posted speed limit and the advisory speed for that curve. Turns that have an advisory speed posted at or below 30 mph shall have an arrow board; see [[#903.6.10 One-Direction Large Arrow Sign (W1-6) (MUTCD Section 2C.12)|EPG 903.6.10 One-Direction Large Arrow Sign.]] <br />
<br />
The Chevron Initiative shall be completed by January 1, 2020.<br />
<br />
Chevron Alignment signs shall not be placed on the far side of a T-intersection facing traffic on the stem approach to warn drivers that a through movement is not physically possible, as this is the function of a Two-Direction (or One-Direction) Large Arrow sign. Chevron Alignment signs shall not be used to mark obstructions within or adjacent to the roadway, including the beginning of guardrails or barriers, as this is the function of an object marker.<br />
<br />
'''Option.''' Turns that have arrow boards may be signed with chevrons instead of an arrow board based on engineering judgment.<br />
<br />
===<center>Table 903.6.11 Chevron Spacing on Curves===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ <br />
! style="background:#BEBEBE"|Degree of Curve !! style="background:#BEBEBE"|Radius (ft.) !! style="background:#BEBEBE"|Spacing on Curve (ft.) !! style="background:#BEBEBE"|Spacing on Turn (ft.) !! style="background:#BEBEBE"|Spacing on Tangent (ft.)<br />
|-<br />
| <br />
|| 10000 || 400 || 200 || 200<br />
|-<br />
|1<br />
| ||304 || 152 ||200<br />
|-<br />
| <br />
| 5000||282||141||200<br />
|-<br />
| <br />
|3000|| 218|| 109|| 196<br />
|-<br />
|2<br />
| ||212|| 106|| 191<br />
|-<br />
| <br />
| 2500||198 ||99 ||178<br />
|-<br />
| <br />
| 2000 ||176 || 88 || 158<br />
|-<br />
|3<br />
| || 172|| 86||155<br />
|-<br />
| ||1800|| 168|| 84|| 151<br />
|-<br />
| <br />
|1600 ||156|| 78|| 140<br />
|-<br />
|4 <br />
| || 148||74|| 133<br />
|-<br />
| <br />
| 1400 || 148|| 74|| 133<br />
|-<br />
| <br />
|1200|| 136|| 68|| 122<br />
|-<br />
|5 <br />
| ||132||66|| 119<br />
|-<br />
| ||1000||124||62|| 112<br />
|-<br />
| ||900||116||58||104<br />
|-<br />
|7 <br />
| || 110|| 55|| 99<br />
|-<br />
| ||800||110|| 55|| 99<br />
|-<br />
| ||700|| 102|| 51|| 92<br />
|-<br />
|9<br />
| || 96|| 48|| 86<br />
|-<br />
| ||600 ||94 ||47 ||85<br />
|-<br />
| || 500|| 84|| 42|| 76<br />
|-<br />
|≥10<br />
| || 80|| 40|| 75<br />
|}<br />
<br />
</center><br />
<br />
==903.6.12 Truck Rollover Warning Sign (W1-13) (MUTCD Section 2C.13)==<br />
<br />
[[image:W1-13.gif|center|125px|thumb|<center>'''W1-13'''</center>]]<br />
<br />
'''Option.''' A Truck Rollover Warning (W1-13) sign may be used to warn drivers of vehicles with a high center of gravity, such as trucks, tankers and recreational vehicles of a curve or turn where geometric conditions might contribute to a loss of control and a rollover as determined by an engineering study. <br />
<br />
'''Standard.''' If a Truck Rollover Warning (W1-13) sign is used, an Advisory Speed Plaque (W13-1P) plaque indicating the recommended speed for vehicles with a higher center of gravity shall accompany it. <br />
<br />
'''Option.''' The Truck Rollover Warning sign may be displayed as a static sign, as a static sign supplemented by a flashing warning beacon, or as a changeable message sign activated by the detection of an approaching vehicle with a high center of gravity that is traveling in excess of the recommended speed for the condition. <br />
<br />
The curved arrow on the Truck Rollover Warning sign shows the direction of roadway curvature. The truck tips in the opposite direction.<br />
<br />
==903.6.13 Hill Signs (W7-1) (MUTCD Section 2C.16)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W7-1.gif|left|thumb|<center>'''W7-1'''</center>|100px]]<br />
||[[image:W7-1c.gif|left|100px|thumb|<center>'''W7-1c'''</center>]]<br />
|}<br />
<br />
'''Guidance.''' The Hill (W7-1) sign should be used in advance of a downgrade where the length, percent of grade, horizontal curvature and/or other physical features requires special precautions on the part of road users.<br />
<br />
The Hill sign and supplemental grade (W7-3P) plaque (refer to [[#903.6.47 Supplemental Arrow Plaques (W16-5P, W16-6P) (MUTCD Section 2C.56)|EPG 903.6.47]]) used in combination should be installed in advance of downgrades for the following conditions:<br />
<br />
A. 5% grade that is more than 3,000 ft. long;<br />
<br />
B. 6% grade that is more than 2,000 ft. long;<br />
<br />
C. 7% grade that is more than 1,000 ft. long;<br />
<br />
D. 8% grade that is more than 750 ft. long;<br />
<br />
E. 9% grade that is more than 500 ft. long;<br />
<br />
F. 11% grade that is more than 400 ft. long;<br />
<br />
G. 13% grade that is more than 300 ft. long;<br />
<br />
H. 15% grade that is more than 200 ft. long; or<br />
<br />
I. 16% or more grade that is any length.<br />
<br />
These signs are also to be installed for steeper grades or where crash experience and field observations indicate a need or at grades of five percent or more where any part of the grade is on a curve sharper than four degrees.<br />
<br />
Supplemental plaques (refer to [[#903.6.42 FERRY CROSSING AHEAD Sign (W3-18)|EPG 903.6.42]]) and larger signs should be used for emphasis or where special hill characteristics exist. On longer grades, the use of the Hill sign with a distance (W7-3aP) plaque at periodic intervals of approximately 1 mile spacing should be considered.<br />
<br />
'''Standard.''' If the percent grade is displayed on a supplemental plaque, the plaque shall be placed below the Hill (W7-1) sign.<br />
<br />
'''Support.''' The Uphill (W7-1c) sign is also available by special request.<br />
<br />
==903.6.14 Hill-Related Supplemental Plaques (W7-3 Series) (MUTCD Section 2C.57)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W7-3aP.jpg|left|thumb|<center>'''W7-3aP'''</center>|100px]]<br />
||[[image:W7-3P.jpg|left|100px|thumb|<center>'''W7-3P'''</center>]]<br />
|}<br />
<br />
<br />
'''Guidance.''' Hill-Related (W7-3 series) supplemental plaques or other appropriate legends and larger signs should be used for emphasis or where special hill characteristics exist. On longer grades, the use of the supplemental distance plaque (W7-3aP) at periodic intervals of approximately 1 mile spacing should be considered.<br />
<br />
==903.6.15 ROAD NARROWS Sign (W5-1) (MUTCD Section 2C.19)==<br />
<br />
[[image:W5-1.gif|center|125px|thumb|<center>'''W5-1'''</center>]]<br />
<br />
<br />
'''Guidance.''' Except as provided below, a ROAD NARROWS (W5-1) sign should be used in advance of a transition on two-lane roads where the pavement width is reduced abruptly to such a narrow width that vehicles traveling in opposite direction cannot simultaneously travel through the narrow portion of the roadway without reducing speed.<br />
<br />
'''Option.''' The ROAD NARROWS (W5-1) sign may be omitted on low-volume local streets that have speed limits of 30 mph or less. Additional emphasis may be provided by the use of object markers and delineators. The Advisory Speed (W13-1) plaque may be used to indicate the recommended speed.<br />
<br />
==903.6.16 NARROW BRIDGE Sign (W5-2) (MUTCD Section 2C.20)==<br />
<br />
[[image:W5-2.gif|center|125px|thumb|<center>'''W5-2'''</center>]]<br />
<br />
'''Guidance.''' A NARROW BRIDGE (W5-2) sign should be used in advance of any bridge or culvert having a two-way roadway clearance width of 16 ft. to 18 ft., or any bridge or culvert having a roadway narrower than the width of the approach travel lanes.<br />
<br />
Additional emphasis should be provided by the use of object markers, delineators and/or pavement markings.<br />
<br />
'''Option.''' A NARROW BRIDGE sign may be used in advance of a bridge or culvert on which the approach shoulders are narrowed or eliminated.<br />
<br />
==903.6.17 ONE LANE BRIDGE Sign (W5-3) (MUTCD Section 2C.21)==<br />
[[image:W5-3.gif|center|125px|thumb|<center>'''W5-3'''</center>]]<br />
<br />
'''Guidance.''' A ONE LANE BRIDGE (W5-3) sign should be used on two-way roadways in advance of any bridge or culvert:<br />
<br />
A. Having a clear roadway width of less than 16 ft.; or<br />
<br />
B. Having a clear roadway width of less than 18 ft. when commercial vehicles constitute a high proportion of the traffic; or<br />
<br />
C. Having a clear roadway width of 18 ft. or less where the sight distance is limited on the approach to the structure.<br />
<br />
Additional emphasis should be provided by the use of object markers, delineators and/or pavement markings.<br />
<br />
==903.6.18 Divided Highway Sign (W6-1) (MUTCD Section 2C.22)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W6-1.gif|left|thumb|<center>'''W6-1'''</center>|100px]]<br />
|}<br />
<br />
'''Guidance.''' A Divided Highway (W6-1) sign should be used on the approaches to a section of highway (not an intersection or junction) where the opposing flows of traffic are separated by a median or other physical barrier.<br />
<br />
'''Standard.''' DIVIDED HIGHWAY supplemental plaque (W6-1c) has been discontinued. MoDOT shall no longer provide DIVIDED HIGHWAY supplemental plaque (W6-1c). Existing DIVIDED HIGHWAY supplemental plaque (W6-1c) shall be left in place until they reach the end of their service The Divided Highway (W6-1) sign shall not be used instead of a Keep Right (R4-7 series) sign on the approach end of a median island.<br />
<br />
==903.6.19 Divided Highway Ends Sign (W6-2) (MUTCD Section 2C.23)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W6-2.gif|left|thumb|<center>'''W6-2'''</center>|100px]]<br />
|}<br />
<br />
'''Guidance.''' A Divided Highway Ends (W6-2) sign should be used in advance of the end of a section of physically divided highway (not an intersection or junction) as a warning of two-way traffic ahead.<br />
<br />
'''Standard.''' DIVIDED HIGHWAY ENDS supplemental plaque (W6-2c) has been discontinued. MoDOT shall no longer provide DIVIDED HIGHWAY ENDS supplemental plaque (W6-2c). Existing DIVIDED HIGHWAY ENDS supplemental plaque (W6-2c) shall be left in place until they reach the end of their service life.<br />
<br />
==903.6.20 Double Arrow Sign (W12-1) (MUTCD Section 2C.25)==<br />
[[image:W12-1.gif|center|125px|thumb|<center>'''W12-1'''</center>]]<br />
<br />
'''Option.''' The Double Arrow (W12-1) sign may be used to advise road users that traffic is permitted to pass on either side of an island, obstruction, or gore in the roadway (see Fig. 903.6.20). Traffic separated by this sign may either rejoin or change directions.<br />
<br />
'''Guidance.''' If used on an island, the Double Arrow sign should be mounted near the approach end. If used in front of a pier or obstruction, the Double Arrow sign should be mounted on the face of, or just in front of, the obstruction. Where stripe markings are used on the obstruction, they should be discontinued to leave a 3 in. space around the outside of the sign.<br />
<br />
[[image:903.6.20.jpg|center|500px|thumb|<center>'''Fig. 903.6.20 Installation For Double Down Arrow Sign'''</center><br />
'''Note:''' The Type 1 Object Marker may be added to this installation if additional emphasis is required, except at signalized intersections. See [[903.2 Extent of Signing#903.2.2 Signing on Interstates, Freeways and Expressways with Full Access Control|EPG 903.2.2]] for mounting height of Type 1 Object Marker.]]<br />
<br />
==903.6.21 DEAD END, NO OUTLET and ROAD ENDS Signs (W14-1, W14-2, W14-13) (MUTCD Section 2C.26)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W14-1.gif|left|thumb|<center>'''W14-1'''</center>|100px]]<br />
||[[image:W14-2.gif|left|100px|thumb|<center>'''W14-2'''</center>]]||[[image:W14-7.gif|left|100px|thumb|<center>'''W14-7'''</center>]]<br />
|}<br />
<br />
'''Option.''' The DEAD END (W14-1) sign may be used at the entrance of a single road or street that terminates in a dead end or cul-de-sac. The NO OUTLET (W14-2) sign may be used at the entrance to a road or road network from which there is no other exit in place of the DEAD END sign.<br />
<br />
The ROAD ENDS (W14-13) sign may be used to warn of a roadway which has no outlet and which terminates in a dead end and may be used in place of the DEAD END or NO OUTLET sign where the used of the DEAD END and NO OUTLET signs would have a negative effect on traffic generators or public perceptions due to the negative connotation of the message.<br />
<br />
'''Standard.''' When the W14-1, W14-2 or W14-13 sign is used, the sign shall be posted as near as practical to the entry point or at a sufficient advance distance to permit the road user to avoid the dead end or no outlet condition by turning off at the nearest intersecting street.<br />
<br />
The DEAD END sign shall be placed at the appropriate distance from the end of the roadway.<br />
<br />
The W14-2 or W14-13 sign shall not be used in place of the DEAD END sign at the end of the roadway. <br />
<br />
The DEAD END sign shall be installed at the end of any state route that physically ends or ends at a private entrance.<br />
<br />
The W14-1, W14-2 or W14-13 sign shall not be used in place of the ROAD CLOSED (R11-2) sign for temporary conditions, such as high water, bridge out, etc.<br />
<br />
'''Guidance.''' The W14-1, W14-2 or W14-13 sign should be installed just beyond the entrance to all state maintained roadways where this condition exists.<br />
<br />
==903.6.22 Low Clearance Sign (W12-2 and W12-2a) (MUTCD Section 2C.27)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W12-2.gif|left|thumb|<center>'''W12-2'''</center>|100px]]<br />
||[[image:W12-2p.gif|left|100px|thumb|<center>'''W12-2a'''</center>]]<br />
|}<br />
<br />
<br />
'''Standard.''' The Low Clearance (W12-2) sign shall be used to warn road users of clearances of clearances less than 12 in. above the statutory maximum vehicle height. The clearance to be indicated on the signs shall be the actual clearance less 2 in. for possible packed snow and ice. All clearance measurements shall be reduced to the nearest lower full inch.<br />
<br />
Posting requirements for Low Clearance signs are as follows:<br />
<br />
: Case I – Two Signs: Where the sign legend for vertical clearance is 15 ft. (15 ft., 2 in. minus 2 in.) or less, but more than 13 ft. 6 in. (13 ft. 8 in. minus 2 in.), two signs shall be used. First, the clearance shall be posted on the structure by an Overhead Low Clearance (W12-2a) sign and, second, a shoulder mounted Low Clearance (W12-2) sign shall be placed about 750 ft. in advance of the structure. When an interchange is involved, the shoulder-mounted Low Clearance (W12-2) sign shall be located about 750 ft. in advance of the off-ramp. The maximum height shown on the signs under these conditions shall be 15 ft. (15 ft., 2 in. measured clearance minus 2 in. for possible paced snow and ice).<br />
<br />
: Case II – Three signs: Where the sign legend for vertical clearance is 13 ft. 6 in. (13 ft. 8 in. minus 2 in.) or less, three signs shall be used. First, the clearance shall be posted on the structure by a Overhead Low Clearance (W12-2a) sign, second, a shoulder mounted Low Clearance (W12-2) sign shall be placed about 750 ft. in advance of the structure, and third, a second Low Clearance (W12-2) sign shall be placed at the nearest intersecting road or wide point in the road at which a vehicle can detour or turn around. The maximum height shown on the signs under these conditions shall be 13 ft. 6 in. (13 ft. 8 in. measured clearance minus 2 in. for possible paced snow and ice).<br />
<br />
: Case III – One Sign: Where the vertical clearance is 15 ft. (15 ft. 2 in. minus 2 in.) or less and where the bridge is state maintained but the road beneath is not, the Overhead Low Clearance (W12-2a) sign shall be mounted on the structure but the shoulder mounted Low Clearance (W12-2) sign shall not be used.<br />
<br />
Vertical clearance signing shall be provided for structures within commercial zones (see Missouri Statute 304.190). The legal maximum limit within commercial zones is 15 feet. Therefore, we shall warn motorists of vertical clearances of 16 ft. 2 in. or less in commercial zone limits. The clearance to be indicated on the signs shall be the actual clearance less 2 in. The signing for clearances of 16 ft. 2 in. or less within commercial zones shall be the same as Case I and Case III used for signing structures of 15 ft. or less.<br />
<br />
'''Guidance.''' The Overhead Low Clearance (W12-2a) sign should be mounted on a structure centered over the lane or lanes affected.<br />
<br />
Where the clearance is less than the legal maximum vehicle height, the W12-2 sign with a supplemental distance plaque (W16-3P) should be placed at the nearest intersecting road or wide point in the road at which a vehicle can detour or turn around.<br />
<br />
In the case of an arch or other structure under which the clearance varies greatly, two or more signs should be used as necessary on the structure itself to give information as to the clearances over the entire roadway.<br />
<br />
Clearances should be evaluated periodically, particularly when resurfacing operations have occurred.<br />
<br />
'''Support.''' The Overhead Clearance (W12-2a) signs have two parts. The first sign indicates the foot dimensions and the second sign indicates the inch dimension. For example of how to sign for a low clearance of an actual measurement of 13 ft. 6 ¾ in., subtract 2 in. for snow. Therefore, a 13 ft. 4 in. measurement would be shown on the sign.<br />
<br />
'''Standard.''' Low Clearance (W2-12b) sign has been discontinued. MoDOT shall no longer provide Low Clearance (W2-12b) signs. Existing Low Clearance (W2-12b) sign shall be left in place until they reach the end of their service life.<br />
<br />
==903.6.23 BUMP and DIP Signs (W8-1, W8-2) (MUTCD Section 2C.28)==<br />
<br />
'''Standard.''' The BUMP and DIP warning signs (W8-1, W8-2) have been discontinued. Existing BUMP and DIP signs (W8-1, W8-2) shall be left in place until the pavement condition is corrected. BUMP and DIP signs will be available as temporary traffic control signs (WO8-1, WO8-2). Guidance can be found in [[:Category:616 Temporary Traffic Control|EPG 616 Temporary Traffic Control]].<br />
<br />
==903.6.24 PAVEMENT ENDS Sign (W8-3) (MUTCD Section 2C.30)==<br />
<br />
[[image:W8-3.gif|center|100px|thumb|<center>'''W8-3'''</center>]]<br />
<br />
'''Guidance.''' A PAVEMENT ENDS (W8-3) word message sign should be used where a paved surface changes to either a gravel treated surface or an earth road surface.<br />
<br />
==903.6.25 SOFT SHOULDER Sign (W8-4) (MUTCD Section 2C.31)==<br />
<br />
[[image:W8-4.gif|center|100px|thumb|<center>'''W8-4'''</center>]]<br />
<br />
'''Option.''' The SOFT SHOULDER (W8-4) sign may be used to warn of a soft shoulder condition. <br />
<br />
'''Guidance.''' Additional shoulder signs should be placed at appropriate intervals along the road where the condition continually exists.<br />
<br />
'''Standard.''' When used, SOFT SHOULDER sign shall be placed in advance of the condition. See [[#Table 903.6.6 Guidelines for Advance Placement of Warning Sign|Table 903.6.6]].<br />
<br />
==903.6.26 Slippery When Wet Sign (W8-5) (MUTCD Section 2C.32)==<br />
<br />
'''Standard.''' Slippery When Wet Warning (W8-5) signs have been discontinued. Existing Slippery When Wet (W8-5) signs shall be left in place until the condition is corrected. Once the condition is corrected, the sign shall then be removed. Slippery When Wet Temporary Traffic Control signs (WO8-5) will be available to warn of this condition temporarily until the condition can be corrected. Guidance can be found in [[:Category:616 Temporary Traffic Control|EPG 616 Temporary Traffic Control]].<br />
<br />
==903.6.27 FALLEN ROCKS Sign (W8-14) (MUTCD Section 2C.32)==<br />
<br />
'''Option.''' The FALLEN ROCKS (W8-14) sign may be used to warn motorist where falling rocks may be on the roadway. <br />
<br />
'''Standard.''' The district shall perform an evaluation of the Fallen Rocks site to determine whether this sign is still necessary. If it is determined that Fallen Rocks is not an issue at the site, the sign will not be replaced at the end of the service life.<br />
<br />
==903.6.28 Advance Traffic Control Signs (W3-1, W3-2, W3-3, W3-4) (MUTCD Section 2C.36)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W3-1.gif|left|thumb|<center>'''W3-1'''</center>|100px]]<br />
||[[image:W3-2.gif|left|100px|thumb|<center>'''W3-2'''</center>]]||[[image:W3-3.gif|left|100px|thumb|<center>'''W3-3'''</center>]]||<br />
[[image:W3-4.gif|left|100px|thumb|<center>'''W3-4'''</center>]]<br />
|}<br />
<br />
'''Standard.''' The Advance Traffic Control symbol signs include the Stop Ahead (W3-1), Yield Ahead (W3-2), and Signal Ahead (W3-3) signs. These signs shall be installed on an approach to a primary traffic control device that is not visible for a sufficient distance to permit the road user to respond to the device (see Table 903.6.28 and Fig. 903.6.28). The visibility criteria for a traffic control signal shall be based on having a continuous view of at least two signal faces for the distance specified in Table 903.6.28.<br />
<br />
'''Support.''' Permanent obstructions causing the limited visibility might include roadway alignment or structures. Intermittent obstructions might include foliage or parked vehicles. <br />
<br />
'''Guidance.''' Where intermittent obstructions occur, engineering judgment should determine the treatment to be implemented.<br />
<br />
The minimum visibility distance of a signal for a facility with a speed limit above 60 mph should be determined by summing the stopping sight distance (see Table 903.6.5) and the assumed queue length. The assumed queue length should be determined by engineering judgment.<br />
<br />
If an advance traffic control sign is warranted for an approach at an intersection of a MoDOT maintained road and non-MoDOT maintained road, the maintainer of the non-MoDOT road should be notified of the condition.<br />
<br />
'''Option.''' An Advance Traffic Control sign may be used for additional emphasis of the primary traffic control device, even when the visibility distance to the device is satisfactory. An advance street name plaque (refer to EPG 903.6.48) may be installed below an Advance Traffic Control sign only if an Advance Traffic Control sign is required.<br />
<br />
The Signal Ahead (W3-3) signs may be double posted on the right-hand and left-hand shoulders on a high speed divided approach.<br />
<br />
A warning beacon may be used with an Advance Traffic Control sign.<br />
<br />
A BE PREPARED TO STOP (W3-4) sign may be used to warn of stopped traffic caused by a traffic control signal or in advance of a section of roadway that regularly experiences traffic congestion.<br />
<br />
===<center>Table 903.6.28 Requirements for Advance Traffic Control Sign Placements</center>===<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" width=550<br />
|+ <br />
! style="background:#BEBEBE"|85<sup>th</sup> Percentile Speed (mph) !! style="background:#BEBEBE"|Minimum Visibility Distance (ft.) <br />
|-<br />
|align="center"|20|| align="center"| 175 <br />
|-<br />
| align="center"|25|| align="center"| 215 <br />
|-<br />
| align="center"|30|| align="center"| 270 <br />
|-<br />
| align="center"|35|| align="center"| 325 <br />
|-<br />
| align="center"|40|| align="center"| 390 <br />
|-<br />
| align="center"|45|| align="center"| 460 <br />
|-<br />
| align="center"|50|| align="center"| 540 <br />
|-<br />
| align="center"|55|| align="center"| 625 <br />
|-<br />
| align="center"|60|| align="center"| 715 <br />
|-<br />
|colspan="2"|Note: Distances in this table are derived from stopping sight distance plus an assumed queue length for shorter cycle lengths (60 to 75 seconds).<br />
|}<br />
<br />
[[image:Figure 903.6.28.jpg|600px|center|thumb|<center>'''Fig. 903.6.28. Example For Placement of Stop Ahead Sign, Condition B: Posted Speed at 55 mph.'''</center>]]<br />
<br />
<br />
'''Standard.''' When a BE PREPARED TO STOP (W3-4) sign is used in advance of a traffic control signal, it shall be used in addition to a Signal Ahead (W3-3) sign and shall be placed downstream from the Signal Ahead (W3-3) sign. <br />
<br />
'''Option.''' The BE PREPARED TO STOP (W3-4) sign may be supplemented with a warning beacon. <br />
<br />
'''Guidance.''' When the warning beacon is interconnected with a traffic control signal or queue detection system, the BE PREPARED TO STOP sign should be supplemented with a WHEN FLASHING (W16-13P) plaque.<br />
<br />
==903.6.29 Advance Ramp Control Signal Signs (W3-7 and W3-8) (MUTCD Section 2C.37)==<br />
<br />
'''Option.''' A RAMP METER AHEAD (W3-7) sign may be used to warn road users that a freeway entrance ramp is metered and that they will encounter a ramp control signal.<br />
<br />
'''Guidance.''' When the ramp control signals are operated only during certain periods of the day, a RAMP METERED WHEN FLASHING (W3-8) sign should be installed in advance of the ramp control signal near the entrance to the ramp, or on the arterial on the approach to the ramp, to alert road users to the presence and operation of ramp meters.<br />
<br />
'''Standard.''' The RAMP METERED WHEN FLASHING sign shall be supplemented with a warning beacon that flashes when the ramp control signal is in operation.<br />
<br />
==903.6.30 Reduced Speed Limit Ahead Signs (W3-5) (MUTCD Section 2C.38)==<br />
<br />
[[image:W3-5.jpg|center|100px|thumb|<center>'''W3-5'''</center>]]<br />
<br />
'''Guidance.''' A Reduced Speed Limit Ahead (W3-5) sign should be used to inform road users of a reduced speed zone where the speed limit is being reduced by more than 10 mph or where engineering judgment indicates the need for advance notice to comply with the posted speed limit ahead. <br />
<br />
'''Standard.''' If used, Reduced Speed Limit Ahead signs shall be followed by a Speed Limit (R2-1) sign installed at the beginning of the zone where the speed limit applies. <br />
<br />
The speed limit displayed on the Reduced Speed Limit Ahead sign shall be identical to the speed limit displayed on the subsequent Speed Limit sign.<br />
<br />
'''Guidance.''' Speed Reduction signs shall be installed in advance of a speed reduction of 15 mph or greater from the posted speed limit. <br />
<br />
'''Option.''' The Speed Reduction sign may also be used on interstates in advance of a 10 mph reduction in speed to provide additional guidance.<br />
<br />
==903.6.31 Merge Signs (W4-1, W4-5) (MUTCD Section 2C.40)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W4-1.jpg|left|thumb|<center>'''W4-1'''</center>|100px]]<br />
||[[image:W4-5.gif|left|100px|thumb|<center>'''W4-5'''</center>]]<br />
|}<br />
<br />
'''Guidance.''' The Merge sign should be installed on the side of the major roadway where merging traffic will be encountered and in such a position as to not obstruct the road user’s view of entering traffic. Where two roadways of approximately equal importance converge, a Merge sign should be placed on each roadway. When a Merge sign is to be installed on an entering roadway that curves before merging with the major roadway, such as a ramp with a curving horizontal alignment as it approaches the major roadway, the Entering Roadway Merge (W4-5) sign should be used to better portray the actual geometric conditions to road users on the entering roadway. The Merge sign should not be used where two roadways converge and merging movements are not required. The Merge sign should not be used in place of a Lane Ends sign where lanes of traffic moving on a single roadway must merge because of a reduction in the actual or usable pavement width.<br />
<br />
==903.6.32 Added Lane Signs (W4-3, W4-6) (MUTCD Section 2C.41)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W4-3.jpg|left|thumb|<center>'''W4-3'''</center>|100px]]<br />
||[[image:W4-6.gif|left|100px|thumb|<center>'''W4-6'''</center>]]<br />
|}<br />
<br />
<br />
'''Guidance.''' The Added Lane (W4-3) sign should be installed in advance of a point where two roadways converge and merging movements are not required. When possible, the Added Lane sign should be placed such that it is visible from both roadways; if this is not possible, an Added Lane sign should be placed on the side of each roadway.<br />
<br />
When an Added Lane sign should be installed on a roadway that curves before converging with another roadway that has a tangent alignment at the point of convergence, the Entering Roadway Added Lane (W4-6) sign should be used to better portray the actual geometric conditions to road users on the curving roadway.<br />
<br />
==903.6.33 LANE END Signs (W4-2, W9-1, W9-2) (MUTCD Section 2C.42)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W4-2.jpg|left|thumb|<center>'''W4-2'''</center>|100px]]<br />
||[[image:W9-1.jpg|left|100px|thumb|<center>'''W9-1'''</center>]]||[[image:W9-2.jpg|left|100px|thumb|<center>'''W9-2'''</center>]]<br />
|}<br />
<br />
<br />
'''Guidance.''' The LANE ENDS MERGE LEFT (RIGHT) (W9-2) sign or the Lane Ends (W4-2) sign should be used to warn of the reduction in the number of traffic lanes in the direction of travel on a multi-lane highway. <br />
<br />
'''Option.''' The RIGHT (LEFT) LANE ENDS (W9-1) sign may be used in advance of the Lane Ends (W4-2) sign or the LANE ENDS MERGE LEFT (RIGHT) (W9-2) sign as additional warning or to emphasize that the traffic lane is ending and that a merging maneuver will be required. <br />
<br />
On one-way streets or on divided highways where the width of the median will permit, two Lane Ends (W4-2) signs may be placed facing approaching traffic; one on the right-hand side and the other on the left-hand side or median. <br />
<br />
'''Support.''' [[620.2 Pavement and Curb Markings (MUTCD Chapter 3B)#620.2.9 Lane Reduction Transition Markings (MUTCD Section 3B.09)|EPG 620.2.9 Lane Reduction Transition Markings]] contains information regarding the use of pavement markings in conjunction with a lane reduction. <br />
<br />
'''Guidance.''' Where an extra lane has been provided for slower moving traffic (see SLOWER TRAFFIC KEEP RIGHT Sign), a Lane Ends (W9-2) word sign or a Lane Ends (W4-2) symbol sign should be installed in advance of the downstream end of the extra lane. <br />
<br />
Lane Ends signs should not be installed in advance of the downstream end of an acceleration lane.<br />
<br />
'''Standard.''' In dropped lane situations, regulatory signs (see [[903.5 Regulatory Signs#903.5.12 Intersection Lane Control Signs (R3-5 through R3-8) (MUTCD Section 2B.19)|EPG 903.5.12]]) shall be used to inform road users that a through lane is becoming a mandatory turn lane. The W4-2, W9-1 and W9-2 signs shall not be used in dropped lane situations.<br />
<br />
==903.6.34 Two-Way Traffic Sign (W6-3, W16-9P) (MUTCD Section 2C.44)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W6-3.gif|left|thumb|<center>'''W6-3'''</center>|100px]]<br />
||[[image:W16-9p.gif|left|100px|thumb|<center>'''W16-9P'''</center>]]<br />
|}<br />
<br />
'''Guidance.''' A Two-Way Traffic (W6-3) sign should be used to warn road users of a transition from a multi-lane divided section of roadway to a two-lane, two-way section of roadway. <br />
<br />
A Two-Way Traffic (W6-3) sign with an AHEAD (W16-9P) plaque should be used to warn road users of a transition from a one-way street to a two-lane, two-way section of roadway. <br />
<br />
'''Option.''' The Two-Way Traffic sign may be used at intervals along a two-lane, two-way roadway and may be used to supplement the Divided Highway Ends (W6-2) sign discussed in EPG 903.6.19. <br />
<br />
'''Standard.''' The TWO WAY TRAFFIC supplemental plaque (W6-3c) has been discontinued. MoDOT shall no longer provide TWO WAY TRAFFIC supplemental plaques (W6-3c). Existing TWO WAY TRAFFIC supplemental plaques (W6-3c) shall be left in place until they reach the end of their service life.<br />
<br />
==903.6.35 NO PASSING ZONE Sign (W14-3) (MUTCD Section 2C.45)==<br />
[[image:W14-3.gif|center|thumb|<center>'''W14-3'''</center>|100px]]<br />
<br />
'''Support.''' The NO PASSING ZONE (W14-3) sign is not to be used on a system-wide basis. It is intended for special use at locations where passing crashes are present and as a measure to correct those accidents.<br />
<br />
'''Standard.''' The NO PASSING ZONE (W14-3) sign shall be a pennant-shaped isosceles triangle with its longer axis horizontal and pointing to the right. When used, the NO PASSING ZONE sign shall be installed on the left side of the roadway at the beginning of no-passing zones identified by pavement markings or DO NOT PASS (R4-1) signs or both (see [[903.5 Regulatory Signs#903.5.16 DO NOT PASS Sign (R4-1) (MUTCD Section 2B.28)|EPG 903.5.16]]). <br />
<br />
The use of the NO PASSING ZONE sign shall be approved by the State Traffic Engineer.<br />
<br />
==903.6.36 Advisory Exit and Ramp Speed Signs (W13-2 and W13-3) (MUTCD Section 2C.14)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W13-2.gif|left|thumb|<center>'''W13-2'''</center>|100px]]<br />
|}<br />
<br />
'''Standard.''' Advisory Exit Speed (W13-2) and Advisory Ramp Speed (W13-3) signs shall be vertical rectangles. The use of Advisory Ramp Speed sign shall be approval by the State Traffic Engineer.<br />
<br />
'''Guidance.''' If used, the Advisory Exit Speed sign should be installed along the deceleration lane and the advisory speed displayed should be based on an engineering study. When a Truck Rollover (W1-13) sign (see EPG 903.6.12) is also installed for the ramp, the advisory exit speed should be based on the truck advisory speed for the horizontal alignment using recommended engineering practices. If used, the Advisory Exit Speed sign should be visible in time for the road user to decelerate and make an exiting maneuver. <br />
<br />
'''Guidance.''' If used, the Advisory Ramp Speed sign should be installed on the ramp to confirm the ramp advisory speed. <br />
<br />
'''Option.''' Where there is a need to remind road users of the recommended advisory speed, a horizontal alignment warning sign with an advisory speed plaque may be installed at or beyond the beginning of the exit curve or on the outside of the curve, provided that it is apparent that the sign applies only to exiting traffic. These signs may also be used at intermediate points along the ramp, especially if the ramp curvature changes and the subsequent curve on the ramp have a different advisory speed than the initial ramp curve.<br />
<br />
[[image:Figure 903.6.38.jpg|thumb|center|600px|<center>'''Fig. 903.6.36 Example of Advisory Speed Signing for an Exit Ramp'''</center>]]<br />
<br />
==903.6.37 Intersection Warning Signs (W2-1 through W2-8) (MUTCD Section 2C.46)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W2-1.gif|left|thumb|<center>'''W2-1'''</center>|100px]]<br />
||[[image:W2-2.gif|left|100px|thumb|<center>'''W2-2'''</center>]]||[[image:W2-3.gif|left|100px|thumb|<center>'''W2-3'''</center>]]<br />
|}<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W2-4.gif|left|thumb|<center>'''W2-4'''</center>|100px]]<br />
||[[image:W2-5.gif|left|100px|thumb|<center>'''W2-5'''</center>]]<br />
|}<br />
<br />
'''Support.''' Intersection Warning Signs are used when there is limited sight distance, crashes, or based on engineering judgment. <br />
<br />
'''Option.''' A Crossroad (W2-1) symbol, Side Road (W2-2 or W2-3) symbol, T-Symbol (W2-4), or Y-Symbol (W2-5) sign may be used in advance of an intersection to indicate the presence of an intersection and the possibility of turning or entering traffic.<br />
<br />
Intersection Warning signs may be used with Advance Traffic Control signs, but not replace the Advance Traffic Control sign. <br />
<br />
The relative importance of the intersecting roadways may be shown by different widths of lines in the symbol. <br />
<br />
An Advance Street Name plaque (see EPG 903.6.48) may be installed above or below an Intersection Warning sign. <br />
<br />
'''Guidance.''' The Intersection Warning sign should illustrate and depict the general configuration of the intersecting roadway, such as crossroad, side road, T-intersection, or Y-intersection. <br />
<br />
Where the side roads are not opposite each other, the symbol for the intersection should indicate a slight offset.<br />
<br />
===Roundabout Warning Signs (W2-6 and W16-17P)===<br />
<br />
'''Standard.''' The Circular Intersection sign shall be installed in advance of any roundabout intersection. The ROUNDABOUT (W16-17P) plaque along with the appropriate Advisory Speed supplemental plaque (W13-1P) shall be installed below the Circular Intersection sign.<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
||[[image:W2-6.gif|left|100px|thumb|<center>'''W2-6'''</center>]]<br />
||[[image:W2-6a.gif|left|100px|thumb|<center>'''W16-17P'''</center>]]<br />
|}<br />
<br />
'''Option.''' If other circular intersections exist, that would not be classified a roundabout, the Circular Intersection (W2-6) sign may be used. <br />
<br />
[[image:Figure 903.6.37.jpg|center|675px|thumb|<center>'''Fig. 903.6.37 Example of Markings for Roundabout Intersections With One-Lane Approaches'''</center>]]<br />
<br />
==903.6.38 Two-Direction Large Arrow Sign (W1-7) (MUTCD Section 2C.47)==<br />
[[image:W1-7.gif|center|100px|thumb|'''W1-7''']]<br />
<br />
<br />
'''Standard.''' The Two-Direction Large Arrow (W1-7) sign shall be a horizontal rectangle. If used, it shall be installed on the far side of a T-Intersection in line with, and at approximately a right angle to, traffic approaching from the stem of the T-intersection (see Figure 903.6.38). <br />
<br />
The Two-Direction Large Arrow sign shall not be used where there is no change in the direction of travel such as at the beginnings and ends of medians or at center piers. <br />
<br />
The Two-Direction Large Arrow sign directing traffic to the left and right shall not be used in the central island of a roundabout.<br />
<br />
'''Guidance.''' The Two-Direction Large Arrow sign should be visible for a sufficient distance to provide the road user with adequate time to react to the intersection configuration.<br />
<br />
[[image:Figure 903.6.38.jpg|thumb|center|650px|<center>'''Fig. 903.6.38 Double Arrow Board'''</center>]]<br />
<br />
==903.6.39 Traffic Signal Signs (W25-1, W25-2) (MUTCD Section 2C.48)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W25-1.gif|left|thumb|<center>'''W25-1'''</center>|100px]]<br />
||[[image:W25-2.gif|left|100px|thumb|<center>'''W25-2'''</center>]]<br />
|}<br />
<br />
'''Support.''' If a left turn trap exists a Traffic Signal sign is needed, unless the signal has a permissive left that is tied to the opposing through (i.e. Dallas phasing). <br />
<br />
'''Standard.''' At locations where either a W25-1 or a W25-2 sign is required based on the provisions in [[902.5 Traffic Control Signal Features (MUTCD Chapter 4D)#902.5.11 Application of Steady Signal Indications (MUTCD Section 4D.05)|EPG 902.5.11 Application of Steady Signal Indications]], the W25-1 or W25-2 sign shall be installed near the left-most signal head. The W25-1 and W25-2 signs shall be vertical rectangles.<br />
<br />
==903.6.40 Vehicular Traffic Warning Signs (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) (MUTCD Section 2C.49)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W11-1.gif|left|thumb|<center>'''W11-1'''</center>|100px]]<br />
||[[image:W11-1a.gif|left|100px|thumb|<center>'''W11-1b'''</center>]]<br />
||[[image:W11-5.gif|left|100px|thumb|<center>'''W11-5'''</center>]]<br />
||[[image:W11-8.gif|left|thumb|<center>'''W11-8'''</center>|100px]]<br />
|}<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W11-10.gif|left|100px|thumb|<center>'''W11-10'''</center>]]<br />
||[[image:W11-12p.gif|left|thumb|<center>'''W11-12P'''</center>|100px]]<br />
||[[image:W11-14.gif|left|100px|thumb|<center>'''W11-14'''</center>]]<br />
|}<br />
<br />
'''Option.''' Vehicular Traffic Warning (W11-1, W11-1b, W11-5, W11-8, W11-10, W11-12P, W11-14) signs may be used to alert road users to locations where unexpected entries into the roadway by trucks, bicyclists, farm vehicles, emergency vehicles, horse-drawn vehicles or other vehicles might occur. <br />
<br />
'''Support.''' These locations may be relatively confined or occur randomly over a roadway segment. <br />
<br />
'''Guidance.''' Vehicular Traffic Warning signs should be used only at locations where the road user’s sight distance is restricted, or the condition, activity or entering traffic would be unexpected. If the condition or activity is seasonal or temporary, the Vehicular Traffic Warning sign should be removed or covered when the condition or activity does not exist. <br />
<br />
Haul routes that are sporadic should use the portable or turnable Truck Crossing installations and have a Contract for Signs at Truck Crossings (TR12), found on p:contract/tr, executed. <br />
<br />
When used, the Horse Drawn Vehicles assemblies should be repeated according to the Share the Road sign. <br />
<br />
'''Option.''' Supplemental Warning plaques (refer to EPG 903.6.42) with legends such as AHEAD (W16-9P), BIKE XING (W11-1b), XX FEET, NEXT XX MILES or SHARE THE ROAD (W16-1P) may be mounted below Vehicular Traffic signs to provide advance notice to road users of unexpected entries. <br />
<br />
'''Standard.''' For an entrance to be eligible for “Emergency Vehicle Entrance” signing, the facility shall be adjacent and visible from the roadway, shall be recognizable as such and shall have direct access to the state roadway system. If the entrance is signalized, the Emergency Vehicle (W11-8) sign with the EMERGENCY SIGNAL AHEAD (W11-12P) supplemental plaque shall be placed in advance of all emergency-vehicle traffic control signals.<br />
<br />
==903.6.41 Non-Vehicular Warning Signs (W11-2, W11-3, W11-4, W11-7, W11-32, W11-33, W16-9P) (MUTCD Section 2C.50)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W11-2.gif|left|thumb|<center>'''W11-2'''</center>|100px]]<br />
||[[image:W11-3.gif|left|100px|thumb|<center>'''W11-3'''</center>]]<br />
||[[image:W11-4.gif|left|100px|thumb|<center>'''W11-4'''</center>]]<br />
||[[image:W11-7.gif|left|thumb|<center>'''W11-7'''</center>|100px]]<br />
|}<br />
<br />
'''Option.''' Non-Vehicular Warning signs may be used to alert road users in advance of locations where unexpected entries into the roadway might occur or where shared use of the roadway by pedestrians, animals or equestrians might occur. <br />
<br />
'''Support.''' The conflicts may be relatively confined or occur randomly over a roadway segment. <br />
<br />
'''Standard.''' Equestrian (W11-7) Crossing signs should only be installed at Public Equestrian Trail Crossings. Existing Equestrian (W11-7) Crossing signs that do not meet the Public Equestrian Trail Crossing criteria, shall be left in place until they reach the end of their service life. <br />
<br />
Deer (W11-3) and Goose (W11-32) Crossing signs shall only be approved for locations that, through an Engineering Study, as supported by historical data, accident reports or data collected by the Department of Conservation and the Department of Transportation on the number of animals killed at a given location. Any existing sign should be removed at the end of its life cycle unless installation is supported by the previous guidance.<br />
<br />
The Pedestrian (W11-2) sign shall be used in advance of a marked pedestrian crossing. At a marked pedestrian crossing the Pedestrian sign and the Diagonal Downward Crossing Arrow (W16-7P) plaque shall be used, except at signalized and stop controlled intersections. <br />
<br />
The Cattle (W11-4) sign shall be issued to an individual only when the Application for Sign at Cattle Crossings contract (TR9), found on P:\contract\TR, has been signed. <br />
<br />
If a post-mounted W11-2 or W11-7 sign is placed at the location of the crossing point where pedestrians or equestrians might be crossing the roadway, a diagonal downward pointing arrow (W16-7P) plaque shall be mounted below the sign. If the W11-2 or W11-7 sign is mounted overhead, the W16-7P plaque shall not be used. <br />
<br />
'''Guidance.''' Deer signs put up due to temporary flooding or development should be reevaluated when the condition stabilizes. <br />
<br />
The district traffic engineering staff is to confirm the need for the Deer (W11-3) and Equestrian (W11-7) sign. <br />
<br />
When used in advance of a pedestrian or equestrian crossing, the W11-2 or W11-7 sign should be supplemented with plaques (see EPG 903.6.46) with the legend AHEAD or XX FEET to inform road users that they are approaching a point where crossing activity might occur. <br />
<br />
The crossing location may be defined with crosswalk markings (see [[:Category:620 Pavement Marking|EPG 620 Pavement Markings]]). <br />
<br />
'''Guidance.''' The mixing of standard fluorescent yellow and fluorescent yellow-green backgrounds within a selected site area should be avoided.<br />
<br />
==903.6.42 FERRY CROSSING AHEAD Sign (W3-18)==<br />
<br />
[[image:W3-10.gif|center|thumb|<center>'''W3-18'''</center>|100px]]<br />
<br />
'''Option.''' The FERRY CROSSING AHEAD (W3-18) sign may be erected for a ferry crossing. A STOP (R1-1) sign at the ferry crossing may be used as a supplement.<br />
<br />
==903.6.43 Use of Supplemental Warning Plaques (MUTCD Section 2C.53)==<br />
<br />
'''Option.''' A supplemental warning plaque may be displayed with a warning or regulatory sign when engineering judgment indicates that road users require additional warning information beyond that contained in the main message of the warning or regulatory sign. <br />
<br />
'''Standard.''' Supplemental warning plaques shall be used only in combination with warning or regulatory signs. They shall not be mounted alone or displayed alone. If used, a supplemental warning plaque shall be installed on the same post(s) as the warning or regulatory sign that it supplements.<br />
<br />
Unless otherwise provided in this guidance for a particular plaque, supplemental warning plaques shall be mounted below the sign they supplement. <br />
<br />
==903.6.44 Design of Supplemental Warning Plaques (MUTCD Section 2C.54)==<br />
<br />
'''Standard.''' A supplemental warning plaque used with a warning sign shall have the same legend, border, and background color as the warning sign with which it is displayed. A supplemental warning plaque used with a regulatory sign shall have a black legend and border on a yellow background. Supplemental warning plaques shall be square or rectangular. <br />
<br />
==903.6.45 Distance Supplemental Plaques (W16-2 Series, W16-3 Series, W16-4P, W7-3aP) (MUTCD Section 2C.55)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
||[[image:W7-3aP.jpg|left|thumb|<center>'''W7-3aP'''</center>|100px]]<br />
|[[image:W16-2P.jpg|left|thumb|<center>'''W16-2P'''</center>|100px]]<br />
|}<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
||[[image:W16-3P.jpg|left|100px|thumb|<center>'''W16-3P'''</center>]]<br />
|[[image:W16-4.gif|left|100px|thumb|<center>'''W16-4P'''</center>]]<br />
|}<br />
<br />
'''Option.''' The Distance Ahead (W16-2 series and W16-3 series) supplemental plaques may be used to inform the road user of the distance to the condition indicated by the warning sign.<br />
<br />
The Next Distance (W7-3aP and W16-4P) supplemental plaques may be used to inform road users of the length of roadway over which the condition indicated by the warning sign exists.<br />
<br />
'''Standard.''' Distances shall be shown in ¼ mile or 100 ft. increments. If the distance is less than a ½ mile then feet shall be used.<br />
<br />
==903.6.46 Advisory Speed Supplemental Plaque (W13-1P) (MUTCD Section 2C.08)==<br />
[[image:W13-1.gif|center|100px|thumb|<center>'''W13-1P'''</center>]]<br />
<br />
'''Option.''' The Advisory Speed (W13-1P) plaque may be used to supplement any warning sign to indicate the advisory speed for a condition. <br />
<br />
The Advisory Speed supplemental plaque may be used in conjunction with any standard warning sign.<br />
<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="410px" align="right" <br />
|-<br />
|<center>'''Engineering Study for Ballbanking'''</center><br />
|-<br />
|The procedure to determine the safe speed on a curve or turn is a ball bank study. To correctly use the ball bank indicator, the ball bank indicator should be mounted on the dashboard of a passenger car and adjusted to read "0" when the car is stationary on a level grade with the ball bank indicator being in a vertical plane. When adjusting the indicator, all personnel who are to be in the car while testing should be in their seats and all four tires should have the same pressure. It is usually best for at least two persons to be in the car while taking the ball bank reading: one for driving, the other for observation and recording. <br />
|-<br />
|The 10-degree reading that can be maintained the complete length of a curve is the appropriate safe speed for that curve. Care must be taken to maintain the car in its proper lane and to maintain a smooth even speed throughout the curve. It will occasionally be found that a curve will have a higher safe speed in one direction than the other. In such cases, the lower safe speed should be used for both directions. Only increments of 5 mph are used on the Advisory Speed Plaque, therefore the curve shall be posted to the nearest 5 mph speed from the survey.<br />
|}<br />
<br />
'''Standard.''' The Advisory Speed plaque shall be used where an engineering study indicates a need to advise road users of the advisory speed for other roadway conditions. The Advisory Speed plaque shall be used with all curve, turn and winding road signs where the curve(s) ballbank at least 5 mph below the posted speed. If the curve(s) ballbank at, or above, the posted speed limit, the advisory speed plaque is optional. If used, the Advisory Speed plaque shall carry the message XX MPH. The speed displayed shall be a multiple of 5 mph. <br />
<br />
Except in emergencies or when the condition is temporary, an Advisory Speed plaque shall not be installed until the advisory speed has been determined by an engineering study. The Advisory Speed plaques shall never be mounted alone. The maximum advisory speed posted shall never be more than the posted speed limit. The Advisory Speed plaque shall only be used to supplement a warning sign and shall not be installed as a separate sign installation. The advisory speed shall be determined by an engineering study that follows established engineering practices.<br />
<br />
'''Guidance.''' Because changes in conditions, such as roadway geometrics, surface characteristics, or sight distance, might affect the advisory speed, each location should be evaluated periodically or when conditions change. <br />
<br />
'''Support.''' The Advisory Speed supplemental plaques are available in 5 mph increments.<br />
<br />
==903.6.47 Supplemental Arrow Plaque (W16-5P, W16-6P) (MUTCD Section 2C.56)==<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W16-5P.jpg|left|thumb|<center>'''W16-5P'''</center>|100px]]<br />
||[[image:W16-6P.gif|left|100px|thumb|<center>'''W16-6P'''</center>]]<br />
|}<br />
<br />
'''Guidance.''' If the condition indicated by a warning sign is located on an intersecting road and the distance between the intersection and condition is not sufficient to provide adequate advance placement of the warning sign, a Supplemental Arrow (W16-5P and W16-6P) plaque should be used below the warning sign.<br />
<br />
'''Standard.''' Supplemental Arrow plaques shall have the same legend design as the Advance Turn Arrow and Directional Arrow auxiliary signs except that they shall have a black legend and border on a fluorescent yellow or fluorescent yellow-green background, as appropriate.<br />
<br />
==903.6.48 Advance Street Name Supplemental Plaque (W16-8P, W16-8aP) (MUTCD Section 2C.58)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W16-8.gif|left|thumb|<center>'''W16-8P'''</center>|100px]]<br />
||[[image:W16-8aP.jpg|left|140px|thumb|<center>'''W16-8aP'''</center>]]<br />
|}<br />
<br />
'''Support.''' Advance street name signing can provide valuable information to the motorist. Intersections that are signed with Intersection Warning (W2 series) or Advance Traffic Control (W3 series) signs typically have inherent sight distance concerns. The addition of the street name to the warning sign can aid a motorist in making decisions in a timely manner.<br />
<br />
'''Option.''' An Advance Street Name (W16-8P or W16-8aP) plaque may be used with any Intersection sign (W2 series) or Advance Traffic Control (W3 series) sign to identify the name of the intersecting street.<br />
<br />
If the side road being signed is maintained by a public agency, the addition of the street name sign may be considered on request.<br />
<br />
'''Guidance.''' Advance Street Name supplemental signs are only to be used with intersection or advance traffic control warning signs that are properly installed according to MoDOT guidelines.<br />
<br />
'''Standard.''' The street name used on an Advance Street Name supplemental sign shall be the approved name used by either the local agency or the Emergency 911 Coordinator.<br />
<br />
When used, the Advance Street Name supplemental plaque shall only be mounted below the W2 or W3 series warning sign or the Mileage Plaque on the same post. The Advance Street Name supplemental plaque for a 36 in. x 36 in. warning sign shall be a maximum of 36 in. wide and for a 48 in. x 48 in. warning sign shall be a maximum of 48 in. wide.<br />
<br />
The lettering on Advance Street Name plaques shall be composed of a combination of lower-case letters with initial upper-case letters.<br />
<br />
If two street names are used on the Advance Street Name plaque, a directional arrow pointing in the direction of the street shall be placed next to each street name. Arrows pointing to the left shall be placed to the left of the street name, and arrows pointing to the right shall be placed to the right of the street name.<br />
<br />
==903.6.49 CROSS TRAFFIC DOES NOT STOP Plaque (W4-4P) (MUTCD Section 2C.59)==<br />
<br />
[[image:W4-4.gif|center|thumb|<center>'''W4-4P'''</center>|100px]]<br />
<br />
<br />
'''Option.''' The CROSS TRAFFIC DOES NOT STOP (W4-4P) plaque may be used in combination with a STOP sign when engineering judgment indicates that conditions are present that are causing or could cause drivers to misinterpret the intersection as an all-way stop.<br />
<br />
'''Standard.''' If a W4-4P plaque or a plaque with an alternate message is used, it shall be mounted below the STOP sign.<br />
<br />
==903.6.50 SHARE THE ROAD Supplemental Plaque (W16-1P) (MUTCD Section 2C.60)==<br />
<br />
[[image:W16-1.gif|center|thumb|<center>'''W16-1P'''</center>|100px]]<br />
<br />
'''Option.''' In situations where there is a need to warn drivers to watch for other slower forms of transportation traveling along the highway, such as bicycles or horse-drawn vehicles, or farm machinery, a SHARE THE ROAD (W16-1P) plaque may be used.<br />
<br />
'''Guidance.''' SHARE THE ROAD (W16-1P) plaques should be installed at a point where vehicles will first encounter slower forms of transportation. <br />
<br />
'''Option.''' SHARE THE ROAD plaques may be installed after any major intersections where new traffic might enter the roadway.<br />
<br />
'''Standard.''' A W16-1P plaque shall not be used alone. If a W16-1P plaque is used, it shall be mounted below either a Vehicular Traffic Warning sign (see EPG 903.6.39) or a Non-Vehicular Warning sign (see EPG 903.6.40). The background color of the W16-1P plaque shall match the background color of the warning sign with which it is displayed.<br />
<br />
==903.6.51 PHOTO ENFORCED Plaque (W16-10aP) (MUTCD Section 2C.61)==<br />
<br />
[[image:W16-10.gif|center|thumb|<center>'''W16-10aP'''</center>|100px]]<br />
<br />
'''Option.''' A PHOTO ENFORCED (W16-10aP) word message plaque may be mounted below a warning sign to advise road users that the regulations associated with the condition being warned about (such as a traffic control signal) are being enforced by photographic equipment.<br />
<br />
'''Standard.''' If used below a warning sign, the PHOTO ENFORCED (W16-10aP) plaque shall be a rectangle with a black legend and border on a fluorescent yellow background.<br />
<br />
==903.6.52 IMPASSABLE DURING HIGH WATER Sign (W8-18, W8-19a, W8-34, W8-35) (MUTCD Section 2C.35)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W8-18.jpg|left|thumb|<center>'''W8-18'''</center>|100px]]<br />
||[[image:W8-19a.jpg|left|40px|thumb|<center>'''W8-19a'''</center>]]<br />
||[[image:W8-17.gif|left|100px|thumb|<center>'''W8-34'''</center>]]<br />
||[[image:W8-18.gif|left|thumb|<center>'''W8-35'''</center>|100px]]<br />
|}<br />
<br />
'''Option.''' The IMPASSABLE DURING HIGH WATER (W18-34) sign may be used to warn of low water crossing, or section of highway where normal rainfall will cause water to be over the roadway, see [[616.23 Traffic Control for Field Operations|EPG 616.23 Traffic Control For Field Operations]]. Where used, this sign may be a flip sign with the combination of a ROAD MAY FLOOD sign (W8-18). <br />
<br />
The LOW WATER CROSSING (W8-35) may also be used to warn of low water crossings.<br />
<br />
'''Standard.''' The Gauge Board (W8-19a) sign shall be used at all low water crossings as a supplement to the IMPASSABLE DURING HIGH WATER sign and shall indicate the depth of the water at the deepest point on the roadway.<br />
<br />
==903.6.53 Hazard Communication Signs==<br />
<br />
'''Support.''' Missouri's Community Right-to-Know law requires visible markings on the outside of buildings, rooms and containers where hazardous substances are present.<br />
<br />
The NFPA 704 marking system uses a diamond-shaped sign (Exhibit D) that is divided into four smaller diamonds. The four smaller diamonds, which are 7½ in. square, are different colors (blue, red, yellow and white) with numbers or symbols that represent the hazards posed by the materials stored inside the building or room. The four quadrants of the sign indicate the potential hazards associated with health (blue), fire or flammability (red), reactivity (yellow) and special hazards (white). Special hazards (white) will not be indicated on our signing.<br />
<br />
Table 903.6.53 contains information on these signs.<br />
<br />
To verify correct marking contact the district safety officer or the Environmental Compliance Coordinator.<br />
<br />
'''Standard.''' Hazard Communication signs shall conform to the National Fire Protection Association (NFPA) standard 704, except that containers may be marked to conform to the OSHA hazard communication standard. <br />
<br />
Each highway facility where reportable quantities of hazardous materials are used or stored shall be visibly marked with a diamond-shaped sign conforming to the NFPA standard 704 marking system. The sign shall be mounted on the outside wall of each building or room next to the pedestrian door. If the pedestrian door is located on the end of the building, a second sign shall be mounted on the front outside wall near the center of the building. <br />
<br />
Bulk striping paint storage docks and/or aboveground storage tanks shall be marked with a sign. Aboveground paint storage tanks shall have a sign (decal) mounted near the top of the tank on the side facing the drive or lot. A post-mounted sign shall be located at the front of paint storage docks in a spot, which is highly visible but not where it will interfere with the loading or unloading of paint. <br />
<br />
Aboveground asphalt storage tanks shall have a sign (decal) mounted near the top of the tank on the end or side facing the drive or lot. If there is more than one tank at a single location, only one tank has to be marked with a sign.<br />
<br />
'''Guidance.''' It may be necessary to periodically change the numbers on signs to conform to current storage conditions. Any changes to the signs should be made within two weeks after current storage conditions change.<br />
<br />
====<center> Table 903.6.58 Hazardous Material Sign Information====<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"<br />
|+ <br />
! style="background:#BEBEBE" width=115|Number !! style="background:#BEBEBE" width=95|FMS !! style="background:#BEBEBE"|Legend !! style="background:#BEBEBE"|Size (in. x in.)<br />
|-<br />
!HCS-10<br />
|8010125005 || HAZ COM BLANK ALUM P || 15 X 15<br />
|-<br />
!HCS-20 <br />
|8010125010|| HAZ COM WHT NRFL SHT|| 15 X 15<br />
|-<br />
!HCS-B0 <br />
|8010125015|| HAZ COM BLU #0 6/SHT ||24 X 15<br />
|-<br />
!HCS-B1<br />
|8010125020|| HAZ COM BLU #1 6/SHT|| 24 X 15<br />
|-<br />
!HCS-B2<br />
|8010125025|| HAZ COM BLU #2 6/SHT|| 24 X 15<br />
|-<br />
!HCS-B3<br />
|8010125030|| HAZ COM BLU #3 6/SHT ||24 X 15<br />
|-<br />
!HCS-B4<br />
|8010125035|| HAZ COM BLU #4 6/SHT ||24 X 15<br />
|-<br />
!HCS-R0<br />
|8010125040|| HAZ COM RED #0 8/SHT ||30 X 15<br />
|-<br />
!HCS-R1<br />
|8010125045|| HAZ COM RED #1 8/SHT ||30 X 15<br />
|-<br />
!HCS-R2<br />
|8010125050|| HAZ COM RED #2 8/SHT ||30 X 15<br />
|-<br />
!HCS-R3<br />
|8010125055|| HAZ COM RED #3 8/SHT ||30 X 15<br />
|-<br />
!HCS-R4 <br />
|8010125060|| HAZ COM RED #4 8/SHT ||30 X 15<br />
|-<br />
!HCS-Y0<br />
|8010125065|| HAZ COM YEL #0 8/SHT ||30 X 15<br />
|-<br />
!HCS-Y1 <br />
|8010125070|| HAZ COM YEL #1 8/SHT ||30 X 15<br />
|-<br />
!HCS-Y2<br />
|8010125075|| HAZ COM YEL #2 8/SHT ||30 X 15<br />
|-<br />
!HCS-Y3<br />
|8010125080|| HAZ COM YEL #3 8/SHT ||30 X 15<br />
|-<br />
!HCS-Y4<br />
|8010125085|| HAZ COM YEL #4 8/SHT ||30 X 15<br />
|}</center><br />
<br />
==903.6.54 Sign Barricades (MUTCD Section 2B.67)==<br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:GB-4L.gif|left|100px|thumb|<center>'''GB-2'''</center>]]<br />
||[[image:GB-4R.gif|left|100px|thumb|<center>'''GB-3'''</center>]]<br />
||[[image:GB-4D.gif|left|100px|thumb|<center>'''GB-4'''</center>]]<br />
||[[image:GB-4E.gif|left|thumb|<center>'''GB-5'''</center>|100px]]<br />
|}<br />
<br />
'''Option.''' Sign Barricades (GB-2 or GB-3) may be used when added emphasis is needed for a change in horizontal roadway alignment (see Fig. 903.6.54.1).<br />
<br />
Sign Barricades (GB-4) may be used opposite the stem of the tee intersection (see Fig. 903.6.54.2).<br />
<br />
'''Guidance.''' Sign barricades should be centered with the approaching lane of traffic. Sign barrocadess should not be used at transitions from 4-lane divided to 2-lane roadways for typical signing at these locations. <br />
<br />
'''Standard.''' Sign Barricades shall be installed per [http://www.modot.mo.gov/business/standards_and_specs/documents/90302.pdf Std. Plan 903.02]. <br />
<br />
GB-4 barricades shall be placed on the far side of the T-intersection with the lines sloping downward in both directions from the center of the barricade. <br />
<br />
GB-3 barricades shall be placed in the line of site of the driver approaching the left turn with the stripes sloping downward from the right to the left. <br />
<br />
GB-2 barricades shall be placed in the line of site of the driver approaching the right turn with the stripes sloping downward from the left to the right. <br />
<br />
GB-5 barricade shall be placed where roadways end and no vehicular movements are provided, the stripes shall slope downward toward the center of the barricade.<br />
<br />
[[image:Figure 903.6.54.1.jpg|thumb|center|650px|<center>'''Fig. 903.6.54.1 Right and Left Barricade Boards'''</center>]]<br />
<br />
[[image:Figure 903.6.54.2.gif|thumb|center|650px|<center>'''Fig. 903.6.54.2 Barricade Board'''</center>]]<br />
<br />
==903.6.55 Shoulder Barricade Assembly==<br />
<br />
[[image:GB-1.gif|thumb|center|125px|<center>'''GB-1'''</center>]]<br />
<br />
'''Option.''' Shoulder barricades may be used for added emphasis of standard warning sign installations at the direction of the engineer.<br />
<br />
'''Standard.''' The shoulder barricade assembly shall consist of three horizontal boards (GB-1L or GB-1R) marked with reflective diagonal stripes and a 48 in. standard warning sign and a 48 in. standard warning sign with the appropriate 30 in. advisory plaque. See Figure 903.6.55 for typical construction.<br />
<br />
GB-1R shoulder barricades shall be installed on the right side of the travelway and have diagonal stripes sloping downward from the right to the left.<br />
<br />
GB-1L shoulder barricades shall be installed on the left side of the travelway and have diagonal stripes sloping downward from the left to the right.<br />
<br />
'''Option.''' Supplemental signs may be installed on the shoulder barricade at the direction of the engineer.<br />
<br />
'''Guidance.''' Shoulder Barricades should be installed on the appropriate sized wood post or on wide flanged structural steel posts.<br />
<br />
[[image:Figure 903.6.55.jpg|thumb|center|650px|<center>'''Fig. 903.6.55 Shoulder Barricade Assembly'''</center>]]<br />
<br />
==903.6.56 Warning Signs Provided for Other Agencies==<br />
<br />
'''Support.''' MoDOT will provide, if requested by the appropriate local traffic authority, warning signs for conditions beyond the end of our right of way.<br />
<br />
If the location for placement of an advance warning sign for a curve, turn, paved road, stop condition or other condition deemed appropriate falls on our right of way, MoDOT will place and maintain the traffic control device on MoDOT right of way at the request of the local traffic authority.<br />
<br />
'''Standard.''' The placement of all traffic control devices on the state highway system shall be governed by the ''Engineering Policy Guide''. MoDOT is responsible for the placement and maintenance of all signs on our right of way.<br />
<br />
==903.6.57 Passing Lane Warning Signs (W6-6a, W6-6aP, W6-16, W6-17)== <br />
<br />
{| style="margin: 1em auto 1em auto"<br />
|-<br />
|[[image:W4-12.gif|left|100px|thumb|<center>'''W6-6a'''</center>]]||[[image:W4-12a.gif|left|100px|thumb|<center>'''W6-6aP'''</center>]]||[[image:W4-10.gif|left|thumb|<center>'''W6-16'''</center>|100px]]||[[image:W4-11.gif|left|100px|thumb|<center>'''W6-17'''</center>]]<br />
|} <br />
<br />
'''Support.''' Alternating passing lanes may be provided on rural, two-lane highways to provide motorists with an opportunity to pass slower vehicles without crossing the centerline. Where passing lanes are provided, operations and safety may be improved by giving motorists advance information about the location of passing lanes. Providing motorists with advance notice of passing lanes may reduce the number of passing maneuvers.<br />
<br />
'''Standard.''' The PASSING LANE ENDS (W6-16), WATCH FOR LEFT-TURNING TRAFFIC IN PASSING LANE (W6-17), PASSING LANE SYMBOL (W6-6a) and PASSING LANE PLAQUE (W6-6aP) signs shall be black legend and fluorescent yellow background and shall only be used in alternating passing lane sections.<br />
<br />
The PASSING LANE ENDS sign shall be used prior to the end of the passing lane to warn motorists the passing lane in that direction of travel is ending and merging back to a single lane. The sign shall be placed in advance of the LANE ENDS MERGE RIGHT (W9-2) sign a distance determined by [[#Table 903.6.6 Guidelines for Advance Placement of Warning Sign|Table 903.6.6 Guidelines for Advance Placement of Warning Sign]].<br />
<br />
The PASSING LANE SYMBOL sign shall be placed at the beginning of each passing lane to indicate a passing lane is now available. The sign shall be oriented so that the arrows on the sign correspond to the actual lane configurations. The PASSING LANE PLAQUE (W6-6aP) shall be used above the PASSING LANE SYMBOL. The supplemental distance plaque (W7-3aP) shall be used below the PASSING LANE PLAQUE. <br />
<br />
'''Option.''' The WATCH FOR LEFT TURNING TRAFFIC IN PASSING LANE sign may be used at locations in a passing lane segment where left turns are common, such as at a county road. This sign may be installed at the judgement of the engineer. <br />
<br />
==903.6.58 TRAVEL SAFE ZONE – FINES DOUBLED Sign (W26-1)==<br />
[[image:903.6.63.jpg|center|130px|thumb|<center>'''W26-1'''</center>]]<br />
<br />
'''Support:''' The TRAVEL SAFE ZONE - FINES DOUBLED (W26-1) sign is not to be used on a system-wide basis. It is intended for special use at locations where severe crashes are occurring. There is a requirement for regional support to focus a safety campaign involving local law enforcement and public information efforts to reduce the number and severity of crashes within the travel safe zone (see [[907.3 Travel Safe Zones|EPG 907.3]]).<br />
<br />
'''Standard:''' A TRAVEL SAFE ZONE – FINES DOUBLED sign shall be used to mark the beginning of a designated travel safe zone. This sign is installed in conjunction with the [[903.5 Regulatory Signs#903.5.52 FINES DOUBLED ENDS Sign (R2-20)|FINES DOUBLED ENDS]] (R2-20) sign.<br />
<br />
<br />
[[image:903.6.jpg|center|775px]]<br />
[[Category:903 Highway Signing|903.06]]</div>Jonesjbhttps://epg.modot.org/index.php?title=233.2_At-Grade_Intersections_with_Stop_and_Yield_Control&diff=27951233.2 At-Grade Intersections with Stop and Yield Control2012-02-08T18:25:24Z<p>Jonesjb: Removed unrealistic requirement for 3 years evaluation of median acceleration lanes.</p>
<hr />
<div>{|style="padding: 0.3em; margin-right:5px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="left" <br />
|- <br />
|'''Figures'''<br />
|-<br />
|[[Media:233.2 Left and Right Turn.pdf|Left and Right Turn Deceleration Distances]]<br />
|-<br />
|[[Media:233.2 Stopping Sight Distance.pdf|'''Green Book Exhibit 3-1''' "Stopping Sight Distance"]]<br />
|-<br />
|[[Media:233.2 Stopping Sight Distance on Grades.pdf|'''Green Book Exhibit 3-2''' "Stopping Sight Distance on Grades"]]<br />
|-<br />
|[http://www.modot.mo.gov/business/standards_and_specs/documents/20350.pdf Type 1 Median Opening]<br />
|-<br />
|[http://www.modot.mo.gov/business/standards_and_specs/documents/20350.pdf Type 2 Median Opening]<br />
|-<br />
|[[media:233.2 Type 3 Median Opening July 2010.pdf|Type 3 Median Opening]]<br />
|-<br />
|[[media:233.2 Type 4 Median Opening.pdf|Type 4 Median Opening]]<br />
|-<br />
|[[media:233.2 Type 5 Median Opening.pdf|Type 5 Median Opening]]<br />
|-<br />
|[[Media:233.2 Median Acceleration Lane.pdf|Median Acceleration Lane]]<br />
|-<br />
|[[Media:233.2 Yielding Right Turn Lane.pdf|Yielding Right Turn Lane]]<br />
|-<br />
|[[Media:233.2 Merging Right Turn.pdf|Merging Right Turn]]<br />
|-<br />
|'''Forms'''<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/DESIGN%20EXCEPTION%20INFORMATION.dot Design Exception Information Form]<br />
|}<br />
[[image:233.2.1.jpg|right|450px]]<br />
Each intersection has the potential for several different types of vehicular conflicts. The possibility of these conflicts actually occurring can be greatly reduced through the provision of proper geometry, sight distance and appropriate traffic control. The avoidance of conflicts and the efficiency of traffic operations still depend on the judgment, capabilities, and response of each individual driver.<br />
<br />
Stopping sight distance is provided continuously along each roadway so drivers have a view of the roadway ahead that is sufficient to allow drivers to stop. The provision of stopping sight distance at all locations along each roadway, including intersection approaches, is fundamental to intersection operation.<br />
<br />
The driver of a vehicle approaching an intersection must have an unobstructed view of the entire intersection, including any traffic control devices, and sufficient lengths along the intersecting roadway to permit the driver to anticipate and avoid collisions. The sight distance needed under various assumptions of physical conditions and driver behavior is directly related to vehicle speeds and to the resultant distances traversed during perception-reaction time and braking.<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Rural Expressway, Median Crossovers'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri98009/RDT01011.pdf Report 2001]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/RI98009B/RDT04013.pdf Report 2004]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/RI98009b/Brf04013.pdf Summary 2004]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
Sight distance is also provided at intersections to allow the drivers of stopped vehicles sufficient view of the intersecting roadway to decide when to enter or cross it. If the available sight distance for an entering or crossing vehicle is at least equal to the appropriate stopping sight distance for the major road, then drivers have sufficient sight distance to anticipate and avoid collisions. However, in some cases, this may require a major-road vehicle to stop or slow to accommodate the maneuver by the minor-road vehicle. To enhance traffic operations, intersection sight distances that exceed stopping sight distances are desirable along the major road.<br />
<br />
==233.2.1 Intersection Sight Distance Criteria==<br />
{|style="padding: 0.3em; margin-left:2px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="360px" align="right" <br />
|-<br />
|<center>'''Intersection and Stopping Sight Distance '''</center><br />
|-<br />
|Stopping sight distance is the length of the roadway ahead that is visible to the driver. The available sight distance on a roadway should be sufficiently long to enable a vehicle traveling at or near the posted speed to stop before reaching a stationary object in its path. Although greater lengths of visible roadway are desirable, the sight distance at every point along a roadway should be at least that needed for a below-average driver or vehicle to stop. <br />
|-<br />
|Stopping sight distance is the sum of two distances: <br />
|-<br />
| - The distance traversed by the vehicle from the instant the driver sights an object necessitating a stop to the instant the brakes are applied and <br />
|-<br />
| - The distance needed to stop the vehicle from the instant the brakes application begins. <br />
|-<br />
|These are referred to as brake reaction distance and braking distance, respectively. <br />
|-<br />
|Intersection sight distance is the distance the driver of a vehicle approaching an intersection needs to have an unobstructed view of the entire intersection, including any traffic control devices, and sufficient lengths along the intersecting major roadway to permit the driver on the approaching roadway to anticipate and avoid potential collisions. The sight distance required for various conditions and driver behaviors is directly related to vehicle speeds and resulting distances traversed during perception-reaction time and braking.<br />
|}<br />
The minimum sight distance for at-grade intersections, entrances, and median openings, measured along the centerline of the main road, is equal to the intersection sight distance based on the operating speed of the main road. This distance is based on a 7.6 ft. eye height for trucks, and a 3.5 ft. eye height for passenger cars. The object height is 3.5 ft. for all vehicles. The minimum sight distance at all grade intersections measured along the minor road, is the stopping sight distance based on the operating speed of the minor road. Exceptions are sometimes necessary where the minor road is being improved to intersect a more important road. Where the more important road is being improved, the minor road is located or improved as required to obtain the required sight distance. If the operating speed of the minor road is not known, a speed of 30 mph is used. Grades are determined and access points are located to provide the required sight distance as well as achieve the necessary spacing requirements contained in the [[941.19 Sight Distance for Entrances|Access Management Guidelines]]. Minimum values for stopping sight distance are described in [[230.2 Vertical Alignment#230.2.5 Stopping Sight Distance and K Factors|EPG 230.2.5 Stopping Sight Distance and K Factors]]. Intersection Sight Distance for a passenger vehicle is based on the stopped vehicle turning left onto a two-lane roadway with no median and grades of 3% or less. Intersection Sight Distance for a combination truck is based on the stopped vehicle turning left onto a two-lane roadway with no median and grades of 3% or less. These sight distance requirements ensure that intersections and access points are visible to approaching traffic. Additional guidance is available in the 2004 AASHTO Green Book (see "Intersection Control" in Chapter 9) for mutli-lane roadways or when grades exceed 3%. <br />
<br />
A triangle of right of way is acquired for required sight distance and visibility at all state route and local road intersections, except where the normal right of way will provide the equivalent of the triangle of right of way. The triangle is graded to the elevation of shoulder point to shoulder point of intersecting roads, to provide the sight distance when the intersection is in a cut. The backslope is graded to the normal cut slope used on the project for the main roadway. Controlled access right of way at intersections for otherwise normal access routes is provided at all state routes and all side roads that intersect a state route carrying over 1700 ADT in the design year.<br />
<br />
The dimensions for the additional triangle of right of way, where required, are determined by connecting points on the centerline of the intersected roadways a distance "d" from the point of intersection, as tabulated in the above table. Where grading is required to provide sight distance, additional right of way may be necessary to provide room for the grading. The operating speed of each intersecting road is used to determine "d". For side road approaches where the operating speed is unknown, an assumed speed of 30 mph is used. The right of way is dimensioned in 5 ft. increments by scaling.<br />
<br />
===<center>Table 233.2.1 Intersection Sight Distance===<br />
{|border="1px" style="text-align:center"<br />
|-style="background:#5F9EA0" <br />
!rowspan="2"| Speed (mph)|| width="200"|Intersection Sight Distance, Passenger Vehicle (ft.)||width="240"|Intersection Sight Distance, Combination Truck (ft.)||rowspan="2"|Length Of Leg, “d” (ft.)<br />
|-style="background:#5F9EA0"<br />
|(Eye Ht. = 3.5 ft.; Object Ht. = 3.5 ft.)||(Eye Ht. = 7.6 ft.; Object Ht. = 3.5 ft.)<br />
|-<br />
|-style="background:#cccccc"<br />
|30||335||505||140<br />
|-style="background:#cccccc"<br />
|35||390||590||165<br />
|-style="background:#cccccc"<br />
|40||445||675||195<br />
|-style="background:#cccccc"<br />
|45||500||760||220<br />
|-style="background:#cccccc"<br />
|50||555||870||245<br />
|-style="background:#cccccc"<br />
|55||610||930||285<br />
|-style="background:#cccccc"<br />
|60||665||1010||325<br />
|-style="background:#cccccc"<br />
|65||720||1090||365<br />
|-style="background:#cccccc"<br />
|70||775||1180||405<br />
|}<br />
</center><br />
<br />
<br />
The values in this table are based upon Exhibits 9-55 and 9-56 of the 2004 AASHTO Green Book.<br />
<br />
==233.2.2 Median Openings==<br />
<br />
Median openings for public use are considered at the intervals outlined in the Access Management Guidelines. Priority is given to the spacing of the openings for state routes, county roads, and major streets. Details for median openings are shown in the Standard Plan 203.50. Maintenance and emergency median openings (i.e. crossovers) are constructed by district maintenance forces and are not included in the design plans.<br />
<br />
Objectives for a median opening include:<br />
* Reducing accidents including both frequency and severity,<br />
* Accommodating the appropriate design vehicle,<br />
* Accounting for passenger vehicles,<br />
* Minimizing driver confusion,<br />
* Providing adequate guidance,<br />
* Decreasing undesirable driver behavior (such as side-by-side queuing) and<br />
* Providing proper balance between mobility and accessibility.<br />
Proper selection of the design for the median opening will provide many years of quality service.<br />
[[image:233.2.1.2 WB-67.jpg|right|300px|thumb|<center>'''The WB-67 is longer than a 60 ft. median width.'''</center>]]<br />
A greater proportion of fatal crashes occur at non-signalized expressway intersections (median openings) when compared to two-lane roadway intersections. Inadequate vehicle placement has caused operational concerns (even at low volumes), such as side-by-side queuing and sight distance restrictions. The inability of a median opening to adequately accommodate the WB-67 design vehicle is evidenced by off-track rutting. The WB-67 is longer than the existing standard 60 ft. median width. Traditional treatment for large vehicle off tracking has been to simply add pavement to the areas where off tracking has occurred. This has added to inadequate vehicle placement by providing a “sea of pavement” with no directional guidance to vehicles. This has not been an effective solution at median openings.<br />
<br />
For most types of median openings, the mainline volume, speed and percent of trucks is not a deciding factor. The biggest design consideration is the crossroad volume. The only exception to this is the Type 1 median opening, which provides no place for turning vehicles to decelerate. In this instance, the mainline volume contributes to the number of accidents at the location.<br />
<br />
The designer will first consider providing access to only the nearest lane (right-in/right-out) during the development of the design of the expressway. If this is not adequate, then other solutions must be developed.<br />
<br />
The presence of heavy truck volumes will determine design elements such as median width and minimum radius. Based on these volumes, the median width at the median opening location may need to be wider than the rest of the length of the road. For example, most expressways are designed for a 60 ft. median, but in order for a large truck to completely cross one set of lanes and wait in the median for a gap to cross or turn into the other set of lanes, the required median width would be 84 ft. Building an entire project with an 84 ft. median to provide adequate width only at crossroads is excessive.<br />
<br />
All median openings must be designed to accommodate the appropriate design vehicle. The decision to accommodate the WB-67 design vehicle is based on the number of trucks and the presence of large truck generators. There are many methods of accommodating the WB-67 besides simply widening the roadway. Truck aprons are to be considered where appropriate. The pavement design for an apron depends on the amount of anticipated truck traffic. If this traffic exceeds 200 trucks per day, the thickness (and mix type) of the apron should be the same as the mainline. If this traffic is less than 200 trucks per day, the thickness of the apron should be 8 inches of PCCP or 11 inches of HMA (using the same mix types as the mainline). <br />
<br />
Horizontal and vertical alignment of the expressway and the crossroad will impact the design of the median opening, especially sight distance. The cost associated with a particular location may influence the type selection. For example, if the two sets of lanes have different vertical elevations, it may be economical to consider a partial interchange that takes advantage of the elevation differences rather than to widen the median to accommodate the grades for an at-grade crossing.<br />
<br />
The need for future expansion must be considered in median opening type selection and design to ensure an appropriate level of flexibility exits for future upgrades. The project must never be overbuilt today on the promise that traffic volumes will grow. However, planning for known future growth is always something that must be considered.<br />
<br />
The impacts of special traffic generators, such as schools, retail development or big box stores are considered for all types of median openings. In these instances it may be necessary to alter the design or use an entirely different type of median opening to address the special needs of the generator.<br />
<br />
Finally, long roadway corridors need to be viewed in the context of maintaining a high level of overall consistency. While it is not necessary each median opening on a route be identical, if there is a choice to be made between two types, consistency within the corridor is desirable. However, it is much more important the right median opening type is used even if each median opening is different.<br />
<br />
The following table provides subjective ratings for public acceptance, driver expectations and safety. Each median opening type has been rated from 1 to 5 (i.e. lowest to highest, or worst to best) rather than simply showing data. For example, the safety scale reflects the number of conflict points existing in the intersection area; this influences accident severity and frequency.<br />
<br />
<br />
{| border="1" cellpadding="5" cellspacing="0" style="background:#CCCCCC"<br />
|- style="background:#FFD700"<br />
! colspan="2"| Category !! Type 1 <div>No Turn Lanes</div> !! Type 2 Turn Lanes !! Type 3 Offset Lefts !! Type 4 <div>Median U-Turn</div> !! Type 5 <div>Partial Grade Separated Interchange</div> !! Interchange<br />
|-<br />
|rowspan="3" align="center"|Operations || align="center"|Mainline Volume || align="center"|Conflicts can create rear-end crashes || colspan="2" align="center"|Not a Primary Factor || align="center"|Not a factor in selection but a factor in design || colspan="2" align="center"|Not a Primary Factor<br />
|-<br />
|align="center"|Crossroad Volume || align="center"|< 10 || align="center"|< 2,000 || align="center"|< 3,000 || align="center"|< 4,000 || align="center"|> 3,000<sup>1</sup> || align="center"|> 4,000<br />
|-<br />
|align="center"|Indirect Turning Movements || colspan="3" align="center"|None || align="center"|Some || align="center"|None || align="center"|None<br />
|-<br />
|rowspan="2" align="center"|Site Conditions || align="center"|Recommended Median Width || colspan="4" align="center"|60 feet || align="center"|80 feet || align="center"|N/A<br />
|-<br />
|align="center"|ROW Impacts || colspan="3" align="center"|Low || align="center"|Medium || align="center"|High || align="center"|High<br />
|-<br />
|rowspan="2" align="center"|Public Involvement || align="center"|Driver Expectations <div>''(1 does not meet, 5 meets)''</div> || align="center"|2 || align="center"|5 || align="center"|4 || align="center"|2 or 3 || align="center"|3 || align="center"|5 <br />
|-<br />
|align="center"|Public Acceptance <div>''(1 low, 5 High)''</div> || align="center"|3 || align="center"|5 || align="center"|4 || align="center"|2 or 3 || align="center"|4 || align="center"|5<br />
|-<br />
|colspan="2" align="center"|Safety Scale <div>''(1 Low, 5 High)''</div> || align="center"|1 || align="center"|2 || align="center"|3 || align="center"|4 || align="center"|4 || align="center"|5<br />
|-<br />
|colspan="2" align="center"|Cost Magnitude ($1,000)<sup>2</sup> || align="center"|40 - 50 || align="center"|100 - 150 || align="center"|150 - 200 || align="center"|100 - 250 || align="center"|2,500 - 3,500 || align="center"|5,000 - 8,000<br />
|}<br />
<br />
'''Notes:'''<br />
<br />
:1. Insufficient data to determine upper threshold for Type 5 volumes.<br />
<br />
:2. Cost Assumption: 60 ft wide median on new construction. Does not include right turn-lanes of R/W acquisition.<br />
<br />
<br />
When an interchange on a roadway is not warranted, MoDOT must adequately explain to the public why choosing the type of median opening provides a safe and long-term solution to their traffic needs. Public meetings can provide sketches and traffic modeling to adequately explain how the facility will operate. This approach has been successful nationwide with public acceptance of a project increasing from low to high.<br />
<br />
Median openings on expressways are classified in one of five types. Each type has particular advantages and disadvantages. The selection of a particular type of opening at a location on an improvement project must receive thorough consideration.<br />
<br />
==233.2.3 Type 1: Median Opening Without Left Turn Lanes==<br />
<br />
The [http://www.modot.mo.gov/business/standards_and_specs/documents/20350.pdf Type 1 Median Opening] has very limited application. Normally, a median opening is not provided for a field entrance or private road, but if an opening is allowed, the Type 1 may be considered. A Type 1 median opening is not normally used for a commercial entrance.<br />
<br />
Since the Type 1 does not have a left turn lane, vehicles must slow down in the “passing” lane of the expressway. The potential for a high-speed rear end crash is high. Therefore, these median openings are only considered when the entrance has very low traffic volumes (less than 10 vehicles per day).<br />
<br />
'''Advantages'''<br />
* Allows for all turning movements at the crossover<br />
* Low cost<br />
<br />
'''Disadvantages'''<br />
* Vehicles must slow to turning speeds in the passing lane of the expressway<br />
* Because there are no turn lanes, the opening is not easily identified by drivers<br />
* Side-by-side queuing of vehicles within the median (undesirable vehicle placement) often occur<br />
* Vehicles within the median and those vehicles approaching the median can create sight distance restrictions<br />
* 18 conflict points<br />
* Difficult to accommodate the WB-67<br />
<br />
'''Additional Items to Consider'''<br />
* If large vehicles are expected to routinely use the median opening, accommodations are necessary:<br />
* 84 ft minimum median width<br />
* Off-tracking aprons<br />
* Right-In/Right Out access to the nearest lane is preferred to providing a Type 1 median opening<br />
<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Rural Expressway, Median Crossovers'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri98009/RDT01011.pdf Report 2001]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/RI98009B/RDT04013.pdf Report 2004]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/RI98009b/Brf04013.pdf Summary 2004]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
==233.2.4 Type 2: Median Opening with Left Turn Lanes==<br />
<br />
The [http://www.modot.mo.gov/business/standards_and_specs/documents/20350.pdf Type 2 Median Opening] is the most commonly used. These median openings usually experience safety issues before their capacity is exceeded. Based on crash experience from Missouri and other national studies, when crossroad volumes are less than 1000 vehicles per day (VPD) they typically operate in a satisfactory manner. As volumes on the crossroad approach 2000 VPD, safety issues usually become more pronounced.<br />
<br />
This type of median opening may be supplemented with other design strategies (deceleration lanes, acceleration lanes, truck aprons, wide medians, etc.) based on traffic and geometric site conditions.<br />
<br />
'''Advantages'''<br />
* Allows for all turning movements at the crossover<br />
* Adaptable to a wide range of median widths<br />
* Can retrofit an existing Type 1 median opening without purchasing additional right-of-way.<br />
* Missouri drivers are very familiar with this design<br />
* Medium to low in cost<br />
* Drainage easily addressed<br />
<br />
'''Disadvantages'''<br />
* Vehicles turning left from the mainline and vehicles using the median opening from the side road can create vehicle placement confusion (ie. who has the right of way)<br />
* [[940.9 Auxiliary Acceleration and Turning Lanes#940.9.10 concerns|Vehicles within the median and those vehicles approaching the median can create sight distance restrictions]]<br />
* Side-by-side queuing of vehicles within the median (undesirable vehicle placement) can occur<br />
* A designer will not consider including signalized intersections for expressways, although one may be installed at an existing location with the recommendation of the Traffic Division. The Type 2 median opening requires additional geometric improvements before signals can be installed and effectively operated<br />
<br />
'''Additional Items to Consider'''<br />
* If large vehicles are routinely expected to use the median opening, the following accommodations must be made:<br />
* 84 ft minimum median width<br />
* Off-tracking aprons<br />
* Provide adequate deceleration length for the left turn lanes to minimize the speed reduction required of vehicles in the “passing” lane that intend to use the median opening<br />
* Right turn deceleration lanes may be needed based on traffic volumes. Offsetting the right turn deceleration lane is preferred unless geometric conditions actually decrease the sight distance<br />
* Median acceleration lanes can be used to provide traffic (i.e. trucks) an opportunity to accelerate before attempting to enter the traffic stream. Median acceleration lanes also provide trucks entering the main roadway from the side road a place to accelerate so they do not have to “fit” into a 40 ft. or 60 ft. median.<br />
<br />
==233.2.5 Type 3: Offset Left Turn Lanes==<br />
<br />
The [[media:233.2 Type 3 Median Opening July 2010.pdf|Type 3 Median Opening]] provides offset left turn lanes at expressway median opening to reduce the frequency of right angle and rear end accidents. This applies to expressway intersections with medians wide enough to accommodate the offset turn lanes. <br />
<br />
'''Advantages'''<br />
* Allows for all turning movements at the crossover<br />
* Serves more left turns than Type 1 or Type 2 Median Openings<br />
* [[940.9 Auxiliary Acceleration and Turning Lanes#940.9.10 benefits|Improves sight distance for mainline left turning traffic]]<br />
* Reduces the number of high-speed conflicts and the risk of severe crash types (i.e. right angle collisions)<br />
* Improves the angle of view, allowing drivers to more effectively use available gaps<br />
* Separates left turning traffic from the mainline roadway<br />
* Addresses side-by-side queuing by keeping left turning traffic separated from those entering the median from the sideroad<br />
* Less confusion in the median opening, paths are defined more clearly than the [http://www.modot.mo.gov/business/standards_and_specs/documents/20350.pdf Type 1 or 2 Median Opening designs] <br />
* Adaptable to a wide range of median widths<br />
* Can retrofit an existing median without purchasing additional right of way and can add a signal without major geometric improvements<br />
* Reduces the number of conflict points<br />
<br />
'''Disadvantages'''<br />
* Drivers may be unfamiliar with this type of intersection<br />
* Mainline left turning traffic must enter the median sooner than expected<br />
* Possible additional drainage and/or pavement requirements<br />
<br />
'''Additional Items to Consider'''<br />
* Design of offset-left turn lane<br />
:::- Parallel lane is necessary to provide motorists enough time to react and move into the left turn lane area; 100-200 ft. is an adequate length for the parallel lane<br />
:::- Storage and deceleration lengths shall be calculated according to each location’s traffic characteristics<br />
:::- It is recommended to provide “positive separation” between the edge of pavements of opposing left turn lanes, as depicted in the drawing below. Having them lined up can, during nighttime, give motorists the false appearance that the lane continues through the median and may lead them to not stop in time.<br />
[[image:233.2.5 recommended.jpg|center|400px]]<br />
<br />
* Accommodating WB-67 trucks or other large vehicles<br />
:::- AutoTurn software should be used to simulate the path and off-tracking of WB-67s or other large vehicles that are expected<br />
:::- 84 ft. minimum width is necessary to allow a truck to fit in the median <br />
:::- Provide paved aprons for off-tracking to prevent rutting <br />
:::- If allowing U-turns, may need to modify sideroad geometrics to make U-turn successful for a WB-67<br />
:::- [[Media:233.2 Median Acceleration Lane.pdf|Median acceleration lanes]] also provide trucks entering the main roadway from the side road a place to accelerate, so they do not have to “fit” into a 40 ft. or 60 ft. median.<br />
[[image:233.2.5 median.jpg|center|300px]] <br />
<br />
* Recommended options for the triangular area<br />
:::- Pave entire area and stripe with chevron pattern<br />
[[image:233.2.5 paved.jpg|center|400px]] <br />
:::- Pave half and stripe with chevron pattern. Grass or rock the rest<br />
[[image:233.2.5 grass or rock.jpg|center|450px]]<br />
:::- Grass or rock the entire area and include lighting. Without the additional pavement and striping that the other two options offer, there is not adequate delineation at night, so therefore lighting is required.<br />
:::- Consider giving options in the contract as to how this triangular area could be constructed to promote lower bids<br />
<br />
* Signing and striping considerations<br />
:::- It is important to clearly mark and sign the intersection. Refer to [[903.13 Typical Signing Applications#Figure 903.13.25 Typical Signing for Type 3 Median Openings|EPG 903.13.25]] for signing.<br />
:::- If the crossroad is a city or county road, it is recommended to install the following left turn lane sign at the beginning of the offset left taper:<br />
[[image:233.2.5 left turn.jpg|center|125px]]<br />
<br />
:::It is also recommended to install an advance intersection guide sign, for example:<br />
[[image:233.2.5 next left.jpg|center|250px]]<br />
<br />
:::- Consider using decision sight distance (refer to Exhibit 3-3 in AASHTO's ''A Policy on Geometric Design of Highways and Streets 2004'', the "Green Book") as guide for placing advanced intersection guide signs before the left turn opening<br />
<br />
:::- Using painted “shark’s teeth” yield bar at the end of the left turn lane<br />
[[image:233.2.5 shark's teeth.jpg|center|275px]]<br />
<br />
:::- Using left turn arrows on the pavement of the offset left turn lane<br />
[[image:233.2.5 left turn arrows.jpg|center|300px]]<br />
<br />
:::- Using “dotted” edgeline extensions across the intersections to provide guidance for motorists in the median as to where to stop<br />
[[image:233.2.5 dotted.jpg|center|200px]]<br />
<br />
* Public information and education programs concerning the operation of offset left-turn lanes and their safety benefits must be considered when these treatments are used for the first time in a given area<br />
<br />
==233.2.6 Type 4: Directional Median Opening with Downstream U-Turns==<br />
<br />
Although variations of the directional median opening with downstream median u-turn design have been used in the United States since 1960, this concept is new to Missouri. The [[media:233.2 Type 4 Median Opening.pdf|Type 4 Median Opening]], eliminates some or all traffic movements through the median. Traffic on the sideroad is forced to turn right onto the main roadway rather than go straight through the median. Through and left turn movements from the sideroad are completed through a downstream median u-turn located approximately 600-1000 ft. from the primary intersection. When the median u-turn is located close to the crossroad, the benefit of reducing right angle crashes is limited. Additionally, a close spacing can also force vehicles to make quick weaving movements at speeds slower than those of the through traffic. The specific location of the median U-Turn is determined by a capacity analysis which includes anticipated weaving movements. The Highway Capacity software and VISSIM are useful in this analysis.<br />
<br />
Typical signing details are found in [[903.13 Typical Signing Applications#Figure 903.13.26 Typical Signing for Type 4 Median Openings|Figure 903.13.26 Typical Signing for Type 4 Median Openings]] and in [[903.13 Typical Signing Applications#Figure 903.13.27 Signing for Type 4 Right-In, Right-Out Openings|Figure 903.13.27 Signing for Type 4 Right-In, Right-Out Openings]].<br />
<br />
Michigan, Florida, Maryland, and North Carolina currently use geometric designs that restrict some or all turning movements at the primary intersection and provide for downstream u-turns. These treatments are primarily used in urban rather than rural areas in Michigan and Florida. Also, the “Michigan U-Turn” is usually signalized with the secondary through movements using the normal intersection path.<br />
<br />
'''Advantages'''<br />
* Reduces crash potential, especially for high severity right angle crashes (conflicts points are reduced to 4). Left and through movements from the sideroad are completed by a two-stage merging movement as opposed to a one stage crossing movement.<br />
* Can accommodate approximately two-times the sideroad volume as compared to the traditional (i.e. Type 2) median crossover type. Typically, it operates effectively for sideroad volumes up to 2,000 VPD and can function for volumes up to 4,000 VPD, depending on site-specific conditions.<br />
* May be easily retrofitted from a Type 1 and Type 2 median opening (depending on site conditions) without purchasing additional right-of-way.<br />
* Low to medium cost<br />
* A designer is not to consider including signalized intersections for expressways, although one may be installed at an existing location with the recommendation of the Traffic Division. This type of median opening can efficiently be retrofitted with traffic signals.<br />
<br />
'''Disadvantages'''<br />
* Most drivers (including typical Missouri drivers) are not familiar with this design<br />
* Requires extraordinary signing and public education efforts<br />
* Creates adverse travel; some movements are indirect<br />
* Creates mainline weaving movements<br />
<br />
'''Additional Items to Consider'''<br />
* Not to be used with median widths less than 60 ft.<br />
* This median opening is a flexible design and may be supplemented with other [[media:233.2.1.6 Variation of Type 4 Median Opening.pdf|design strategies]] (acceleration/deceleration lanes, wide medians, etc.) based on site-specific traffic and geometric conditions. For instance, median acceleration lanes can be used to provide traffic (i.e. trucks) an opportunity to accelerate before attempting to enter the main roadway traffic stream.<br />
<br />
==233.2.7 Type 5: Partial Grade Separated Intersection==<br />
<br />
A [[media:233.2 Type 5 Median Opening.pdf|Type 5 Median Opening]], or Partial Grade Separated Intersection, is considered a hybrid of two common types of median openings]; the traditional diamond interchange for one direction of traffic, and a Type 2 median opening with median acceleration/deceleration lanes for the opposing direction of traffic. Since this type of median opening is essentially an interchange involving construction of a bridge structure, providing it at a rural expressway location must be only considered when less costly alternatives have been exhausted as the result of safety concerns and capacity issues. This type of median opening can be used as a low cost alternative for a “trumpet” style interchange.<br />
<br />
This type of median crossing is used to eliminate the frequency of collisions between left turning and opposing through vehicles, as well as rear-end crashes of vehicles traveling in the same direction. This crossing can be used for any expressway intersection but is best suited to “T” type intersections where the crossroad traffic volumes exceed what is considered acceptable for traditional “at-grade” intersections.<br />
<br />
'''Advantages'''<br />
* Allows for all turning movements at the crossover<br />
* Minimizes potential for severe right angle crashes<br />
* Provides a wider median for long vehicles, such tractor-trailer trucks<br />
* Separates left turning traffic from the mainline roadway<br />
* Has less right-of-way impact than a full diamond or trumpet interchange<br />
* Cost is significantly less than a traditional diamond interchange<br />
* A blend of two familiar configurations satisfies driver expectation<br />
* Could retrofit an existing median crossing without purchasing additional right-of-way, if existing terrain is acceptable (i.e.: profile of one lane is higher than other)<br />
<br />
'''Disadvantages'''<br />
* Cost – bridge structure, additional grading, pavement, and right-of-way<br />
* Right-of-way impacts are higher than with an at-grade intersection<br />
* On straight alignments a median flare is required to accommodate the grade separation; thus introducing horizontal curvature<br />
* The possibility of additional drainage requirements near the bridge<br />
<br />
'''Additional Items to Consider'''<br />
* Public information and education programs must be considered concerning the operation of the Type 5 median opening including the resultant safety benefits when this treatment is used for the first time in an area<br />
* Additional signage is necessary to avoid driver confusion and thus prevent the motorist from entering the wrong roadway against opposing traffic, especially on the at-grade intersection side<br />
* Develop detailed guidelines and parameters for use and application<br />
* Instruct designers on the proper application of this type if intersection<br />
<br />
If a median opening is to be constructed of portland cement concrete, the plans will show the joint layout. To avoid sympathy cracks in the travelway, it is desirable to match median opening joints with the adjacent travelway joints and avoid specifying a median opening joint that will intersect the adjacent travelway where no joint exists. It is acceptable for joints in the centerline of the median opening not to match directly. Additional information concerning pavement joints can be found in the Pavement article.<br />
<br />
==233.2.8 State Routes and Important Roads and Streets==<br />
<br />
Highways are designed to provide for the safe, efficient and economical transportation of persons and goods. The success of a design is dependent on proper planning, geometric design, and efficient traffic operations. The following paragraphs only discuss general requirements. Variations required by location and local conditions will usually offer an infinite number of solutions for specially designed at-grade intersections.<br />
<br />
Designs for important side road intersections are based on a volume product. For volume products equal to or greater than 700,000 the design shown on [http://modot.mo.gov/business/standards_and_specs/documents/20365.pdf Standard Plan 203.65] is used. For volume product intersections less than 700,000, see [http://modot.mo.gov/business/standards_and_specs/documents/20362.pdf Standard Plans 203.62.] The volume product is the product of Vm x Vc. Vm is the design AADT on the major approach (one direction volume for divided and both direction volume for 2-way). Vc is the design AADT on the minor approach. Additional information concerning intersection design can be found in the Access Management Guide.<br />
<br />
Efficient traffic operation is dependent upon geometric design. It is desirable this design considers traffic signal control as a design criterion at all intersections where traffic conflicts are present. When this is not done and traffic signal control becomes necessary, the net result is signals are poorly located with respect to driver vision, disregarded protected left turning movements, and other necessary requirements for efficient traffic signal control compromised or forgotten.<br />
<br />
Grades are designed in accordance with [[230.2 Vertical Alignment|vertical alignment]] criteria.<br />
<br />
Schematic details for grade intersections are indicated on the preliminary plan, along with traffic data, including turning movements. Approval of the preliminary plan constitutes approval of the schematics of the intersections.<br />
<br />
==233.2.9 Roadway Approaches==<br />
<br />
The location and design of approaches affect the safety and traffic handling capacity of the highway. Therefore, the location and design of each feature receives careful consideration. Each approach is designed with appropriate width and radii that will permit entry of the design vehicle without encroachment on opposing traffic lanes. Access Management Guidelines will be used to determine the number, the location and the spacing requirements for approaches and driveways.<br />
<br />
Direct access is not allowed to the through lanes on freeways since they are designed with full control of access. [[:category:940 Access Management|Access Management Guidelines]] are used to determine the number of access points provided on all other facilities (i.e. controlled access and normal right of way).<br />
<br />
{|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="190px" align="right" <br />
|-<br />
|'''Additional Information on Driveway Maintenance'''<br />
|-<br />
|[[941.29 Maintenance of Residential, Commercial and Public Road Entrances|Maintenance of Residential, Commercial and Public Road Entrances]]<br />
|}<br />
==233.2.10 Driveway and Approach Pavement Design Criteria==<br />
<br />
Driveways are designed in accordance with the details shown on the standard plans. The grade controls are followed if at all practicable. Driveway and approach pavement thickness shall be a minimum of 5 ¾ in., using one of the following: 1 ¾ in. BP-1 on 4 in. PMBB or jointed plain concrete without dowels. The Construction and Materials Pavement Section should be consulted for actual design thicknesses.<br />
<br />
==233.2.11 Capacity==<br />
<br />
The appropriate capacities for at-grade intersections without signals are given in the following table. A more detailed capacity analysis is made as outlined in the Highway Capacity Manual, to determine the exact needs and requirements for the intersection.<br />
<br />
{| border="1" cellpadding="8" align="center" <br />
|+ '''TRAFFIC CAPACITIES FOR AT-GRADE INTERSECTIONS WITHOUT SIGNALS <div>(Two-way Design Hourly Volumes)</div>'''<br />
|- <br />
|style="background:#FFD700"|2-Lane through Highway||style="background:#cccccc"|400||style="background:#cccccc"|500||style="background:#cccccc"|600<br />
|-<br />
|style="background:#FFD700"|Crossroad||style="background:#cccccc"|250||style="background:#cccccc"|200||style="background:#cccccc"|100<br />
|- <br />
|style="background:#DAA520"|4-Lane through Highway||style="background:#cccccc"|1000||style="background:#cccccc"|1500||style="background:#cccccc"|2000<br />
|-<br />
|style="background:#DAA520"|Crossroad||style="background:#cccccc"|100||style="background:#cccccc"|50||style="background:#cccccc"|25<br />
|}<br />
<br />
<br />
==233.2.12 Islands==<br />
<br />
Islands are triangular or longitudinal. Triangular islands are generally used on the minor approach to an at-grade intersection, crossovers for major side roads, state routes and major streets, and on ramp terminals at the crossroad or streets at interchanges. Islands at ramp termini are placed in accordance with alignment controls of [[234.2 Diamond Interchanges#234.2.1.1 Ramp and Preliminary Plan criteria|diamond interchanges]]. Islands for at-grade intersections are placed in accordance with [http://www.modot.mo.gov/business/standards_and_specs/documents/20365.pdf Standard Plan 203.65]. Islands when required at crossovers are placed in accordance with the standard plans. Where the highway shoulder is carried through the intersection, the island is placed at the edge of the shoulder. The side of a longitudinal island adjacent to through-traffic lanes is offset from the edge of the traveled way by at least 2 ft. The island may be offset a greater distance if necessary or desirable to eliminate a particular hazard.<br />
<br />
There are two primary types of islands. They are:<br />
<br />
Divisional Islands<br />
These are normally longitudinal islands used to divide opposing traffic to positively restrict encroachment by vehicles. They are at least 4 ft. wide and 12 ft. long. Preferably, they are 20 ft. in length. A divisional island nose is offset a minimum of 4 ft. from the projected edge of the travelway of the crossroad or street. Use AutoTurn to verify placement from turning vehicles. Divisional islands are always constructed with barrier type curbs and basic lighting is provided to the extent necessary to illuminate the ends of the islands. Examples of divisional islands are<br />
* short bulb-type median islands used to provide protected left turn movements,<br />
* all islands between opposing traffic streams,<br />
* all islands established for the purpose of locating traffic signal poles or lighting poles.<br />
<br />
Channelizing Islands<br />
These islands are used to guide and direct same direction traffic streams or diverging traffic streams. Channelizing islands may consist of painted areas, flush sodded areas, or raised islands. The islands are at least 75 ft<sup>2</sup> in area or about 10 ft. on a side. Where raised channelizing islands are used, they are constructed with mountable type curbs. Channelizing islands are not lighted except when lighting is justified by other warrants. Examples of channelizing islands are those established for:<br />
* guiding parallel or diverging traffic streams<br />
* locating small signs<br />
* providing pedestrian refuge<br />
* reducing large paved areas at intersections.<br />
When it is unclear what type of island is necessary, the island is classed channelizing to eliminate the need for lighting. In those cases where it is apparent that traffic signals will be installed within a reasonable period of time after construction at the intersection or interchange, divisional islands will be designed and lighted (by direct reflectance) with the initial construction. Additional information about islands is given in Chapter 9 of the AASHTO Green Book.<br />
<br />
==233.2.13 Auxiliary Lanes==<br />
<br />
Auxiliary lanes are provided on the major roadway and are encouraged on the minor roadway where possible to allow turning vehicles to slow and be stored out of the through traffic lanes. It is desirable to provide them since they improve safety, improve intersection capacity, and allow for the most efficient methods of controlling traffic. Often, auxiliary lanes can be added by utilizing existing shoulders. Consult the [[:category:940 Access Management|Access Management Guidelines]] for additional auxiliary lane information.<br />
<br />
==233.2.14 Length of Auxiliary Lanes==<br />
<br />
The length of a full width auxiliary lane consists of a deceleration length plus a storage length. Storage length is determined on the basis of the maximum possible total time cycle, peak hour traffic volume, and average storage length required per vehicle.<br />
<br />
The length necessary is calculated by multiplying the average length required per vehicle (both trucks and cars) times the number of vehicles arriving per time cycle in the peak hour and is determined by the formula:<br />
<br />
:<math>L = \frac{ \left( \% PC \times 25 \right) + \left( \%TK \times 40 \right)}{100} \times \frac{ \left( vph \right) \times \left( cl \right)}{3600}</math> <br />
<br />
Where:<br />
<br />
:L = length, ft.<br />
:vph = vehicles per hour (design peak hour)<br />
:cl = cycle length in seconds (use 120 seconds for unsignalized locations)<br />
:PC = passenger cars, pickup and panel trucks<br />
:TK = single unit or combination tractor trailer trucks and buses<br />
:% = percent as a whole number<br />
<br />
==233.2.15 Deceleration Length==<br />
<br />
[[Media:233.2 Left and Right Turn.pdf|Deceleration distances]] (distances provided in the table reflect a 10 mph speed reduction) include minimum and desirable lengths and are provided where practical.<br />
<br />
The desirable deceleration length represents the length required for a driver to react to a forming queue at an upcoming intersection and apply the brake coming to a stop behind the forming queue. This is a conservative approach. The minimum deceleration length represents only the braking distance required to come to a stop with a more aggressive deceleration rate. This is the less conservative approach. [[Media:233.2 Stopping Sight Distance.pdf|Exhibit 3-1]] of the AASHTO Green Book can be consulted for specific deceleration rates while [[Media:233.2 Stopping Sight Distance on Grades.pdf|Exhibit 3-2]] can be consulted (to determine increases in deceleration rates due to grades) for roadway grades equal to or exceeding 3%.<br />
<br />
==233.2.16 Required Storage Length==<br />
<br />
The required storage length for use in design is 1.5 times the calculated storage for major streets and 2.0 times the calculated storage for freeway off-ramps. A 50 ft. minimum storage length is desirable.<br />
<br />
The calculated required length may be varied, when necessary, to provide a practical design consistent with capacity limiting features of the street approaches beyond the limits of the proposed improvement or with the unavoidable conflicts with other traffic movements on the same approach.<br />
<br />
==233.2.17 Left Turn Lanes==<br />
<br />
Left turn lanes are considered on roadways where traffic volumes are high enough or safety considerations are sufficient to warrant them. [[:category:940 Access Management|Access Management Guidelines]] are used to determine if left turn lanes are warranted. Where the peak hour left-turning traffic exceeds 300 vph, dual left turn lanes are considered. If the peak hour left-turning traffic exceeds 600 vph, a three lane left turn facility is considered. Left-turn lanes may also be considered at intersections with poor visibility or a history of crashes. Left-turn lanes are at least 10 ft. wide with additional width provided for striping of flush medians or for curb clearances of barrier curbs for raised medians. Left-turn lanes for 30 or 40 mph operating speeds are developed according to certain minimum transitions and are constructed using barrier curbs. They are lighted by direct reflectance (see [[:Category:901 Lighting|EPG 901 Lighting]]) to the extent necessary to illuminate the ends. Left-turn lanes for 50 or 60 mph operating speeds are also developed according to [[Media:233.2 Left and Right Turn.pdf|minimum transitions]]. Left-turn lanes developed from continuous medians are constructed with barrier curbs for at least the length of the left-turn storage with the barrier end lighted by direct reflectance. Additional information concerning storage length is discussed later in this article.<br />
<br />
The use of a divisional island at an intersection to separate the left turning traffic from same direction through traffic may be desirable, particularly where opposing traffic is separated by a wide median. This island will make a left turn from an auxiliary left turn lane mandatory and requires lane control signing.<br />
<br />
At an intersection with multiple left-turn lanes, two or three vehicles will be simultaneously making left turns. Therefore, the number of receiving lanes on the downstream roadway will be the same as the number of left-turning lanes. Sometimes at an intersection with multiple left-turn lanes, the number of receiving lanes on the downstream roadway may be one less. In this situation, a multiple left turn may be installed by including a transition section on the receiving roadway, essentially creating a merging section with a lane-drop condition at another location downstream.<br />
<br />
The distance measured from the beginning of the departing roadway to the beginning of the lane-drop location, excluding the lane-drop taper section, is known as the Merging Section Length. This length must be sufficiently long to avoid any delay to the left turning and through vehicles on the approach. When this length is insufficient, vehicles traveling on the lane being dropped will be forced to slow, stop or perform an unsafe maneuver. This results in undesirable traffic operations and safety problems, caused by queues overflowing into the intersection. A microsimulation analysis, using the VISSIM software package, is performed to determine the appropriate downstream lane-drop distance to avoid disruption of traffic.<br />
<br />
The analysis requires the following data:<br />
* Intersection movement volumes<br />
* Percentage of heavy vehicles<br />
* Operating speed of intersecting roadways<br />
* Signal timing plan (including left turn green time)<br />
* Intersection geometry (including left turn length)<br />
* Expected lane distribution in the left turn lane(s) (observed or predicated percentage of vehicles using each left turn lane prior to the transition section in anticipation of the lane drop)<br />
* The location and turning movement information of any driveways located in the Merging Section (including a driveway that is the destination of the lane-drop).<br />
<br />
The analysis will also compare delay for left turning vehicles in the Merging Section for varying Merging Section lengths. The length that produces the optimum delay is selected.<br />
<br />
==233.2.18 Right Turn Lanes==<br />
<br />
Warrants for right turn lanes are determined by the Access Management Guidelines. To prevent through vehicles from being falsely led into the auxiliary right turn lane, an abrupt taper is used at the beginning of the lane. At locations where it is either impractical or not warranted to provide an auxiliary right turn lane, a channelizing island will reduce right turning maneuver conflicts with through traffic. However, a few straight through vehicles stopped in the right lane waiting for a gap in traffic will block the right turn movement. Conversely, a few right turning vehicles stopped while waiting for a gap in the cross street traffic will block the right lane for through vehicle storage.<br />
<br />
With certain geometric conditions, it may be desirable to offset the right turn auxiliary lane for safety reasons. [[940.9 Auxiliary Acceleration and Turning Lanes#940.9.10 benefits|Offset right turn lanes can reduce severe right angle crashes]] by allowing crossing vehicles an unobstructed view of through traffic.<br />
<br />
==233.2.19 Median Acceleration Lanes==<br />
<br />
It may become necessary to provide a [[Media:233.2 Median Acceleration Lane.pdf|left hand acceleration lane]] along the median side of a four lane divided expressway downstream of a median crossover. Use of this lane is not “typical” and must not be viewed as an acceptable addition to all median crossings throughout the state. In the event a core team determines the provision of such an acceleration lane is warranted, notification must be submitted to the Traffic and Highway Safety Division, prior to the completion of the plans. <br />
<br />
The following warrants shall be used to establish the need for a median acceleration lane: <br />
<br />
:* There is accident history at a specific expressway intersection. Of particular concern are right angle, sideswipe, and rear end accidents involving trucks.<br />
:* There is a high percentage of truck traffic originating on the minor roadway. Additionally, these trucks are of such length they cannot be accommodated within the median opening of the expressway.<br />
:* There is poor sight distance at the location that does not provide sufficient time for a motorist in the passing lane of the expressway to avoid a slow moving truck in the passing lane downstream of the median crossover.<br />
:* There are limited gaps available in the major road traffic stream.<br />
<br />
The median acceleration lane must be sufficiently long to permit acceleration of trucks to the 85<sup>th</sup> percentile speed for vehicles operating on the expressway. The acceleration lane must have a total width of 14 ft. with sufficient striping to denote a lane width of 12 ft. with a 2 ft. offset from the left through lane. A 4 ft. wide shoulder must be provided on the median side of the acceleration lane.<br />
<br />
==233.2.20 Turning Radii==<br />
<br />
Minimum design vehicle turning radii are shown in the following table. These radii are satisfactory as minimum design where turning speeds of 10 mph or less are appropriate at intersections. The radii for turning movements at urban street intersections can be less where the extra pavement width serves to increase the useable radius. When curbs are used, it is desirable to use flatter curves than those in the minimum edge of traveled way designs.<br />
<br />
The choice of minimum design for intersection radii is given in Chapter 9 of the AASHTO Green Book. This identifies the turning radii used for the design of various roadway facilities and the type of design vehicle to use as the control. Turning paths are checked using AutoTurn software for all allowed movements from each approach, to verify that the design vehicle can be accommodated. Best practices for use of AutoTurn include:<br />
* Turn from center of lane to center of lane<br />
* Use steer radius of 75 ft. for merging right turn<br />
* Use steer radius of 50 ft. for yielding right turn<br />
* Use steer radius of 50 ft. for left turn<br />
<br />
The WB-67 (WB-20) is used as the design vehicle for geometric radii for ramp terminals on the interstate and primary system, as well as for adjacent outer roads and entrances where it is anticipated this vehicle will operate. This design vehicle is the maximum semitrailer (53 ft trailer length) able to legally operate in Missouri.<br />
<br />
{|border="1" style="text-align:center"<br />
|-style="background:#BDB76B" <br />
! DESIGN VEHICLE||MINIMUM SIMPLE TURNING RADIUS (ft.)||Edge of Traveled Way Design Simple Curve Radius (ft.) (Based on 90 degree Turn)<br />
|-style="background:#cccccc"<br />
|Passenger Car||24||30<br />
|-style="background:#cccccc"<br />
|Truck||42||50||<br />
|-style="background:#cccccc"<br />
|School Bus (S-Bus 40)||39.4||-<br />
|-style="background:#cccccc"<br />
|City Bus||42||- <br />
|-style="background:#cccccc"<br />
|Intermediate Semi Trailer(WB-50)||45||60’ w/4.0’ offset & 15:1 Taper<br />
|-style="background:#cccccc"<br />
|Interstate Semi-Trailer (WB-67)||45||125’ w/4.5’ offset & 30:1 Taper<br />
|}<br />
<br />
A simple curve with taper combinations is used for the design of channelized right turns to provide for the turning movement of semitrailer combinations. Minimum edge of travelway designs for a simple curve with taper combinations are shown in Chapter 9 of the AASHTO Green Book, for various type vehicles and skews of intersecting roads. The goal is to provide the best turning radius for the roadway design that fits the context of the site including consideration of the following options:<br />
<br />
* '''Yielding right turn lane'''. When a departure auxiliary lane is not present, a yielding right turn lane can be used. The [[Media:233.2 Yielding Right Turn Lane.pdf|yielding right turn]] design provides a turning vehicle alignment with an improved field of view of approaching traffic. The improved visibility allows improved judgment of gaps in the cross-street traffic with a lower incidence of rear end collisions.<br />
* '''Merging right turn lane'''. When a departure auxiliary us present, a [[Media:233.2 Merging Right Turn.pdf|merging right turn lane]] is used. The merging right turn design provides a simple radius curve tangent to two intersecting roadways.<br />
<br />
==233.2.21 Turning Roadway Widths==<br />
<br />
The volume of turning traffic and the type of vehicles to be accommodated on the roadway control travelway widths. Where lane widths of channelized right turn lanes exceed 20 ft. in width, lane delineation with painted lane markings are appropriate to restrict the turning movement operation to one lane use. Vehicles with wider offtracking wheel paths can still use the extra paved width to negotiate the turn. Either AutoTurn or Chapter 3 of the AASHTO Green Book can determine required roadway widths for vehicle offtracking. An additional 1 ft. clearance outside the maximum wheel offtracking along each side is provided for the turning roadway width.<br />
<br />
==233.2.22 Skews==<br />
<br />
Skew of at-grade intersections and entrances should be minimized. The desirable skew is at or below 20 degrees. Ideally, the intersection would have no skew at all.<br />
<br />
==233.2.23 Crossroad Design Criteria==<br />
<br />
Crossroads are sometimes reconstructed some distance beyond normal intersection limits because of design controls or for the construction of grade separations or interchanges. In these cases, the reconstruction is planned to meet basic design criteria based on the functional classification and design traffic on the crossroad whether the crossroad is a state route or not. When the crossroad is not part of the state highway system only the portion of the crossroad within the limits of the “normal” right of way will be improved. Normal right of way includes sight distance right of way purchased at public road approaches.<br />
<br />
==233.2.24 Maintenance and Emergency Crossovers==<br />
<br />
Maintenance and emergency crossovers may be constructed on [[232.5 Freeways|freeways]] and [[232.4 Expressways|expressways]] so that maintenance, emergency and law enforcement vehicles can avoid extremely adverse distances. These crossovers <br />
:* facilitate maintenance activities such as snow removal and<br />
:* provide ample access for law enforcement or emergency medical services responding to roadway incidents.<br />
<br />
Information concerning their location and requirements for construction can be found at [[:Category:240 Maintenance and Emergency Crossovers|EPG 240 Maintenance and Emergency Crossovers]]. <br />
[[category:233 At - Grade Intersections]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:626_Rumble_Strips&diff=27948Category:626 Rumble Strips2012-02-08T17:23:09Z<p>Jonesjb: Clarified the intent of collaboration on the omission and modification of systemwide safety treatments.</p>
<hr />
<div>[[image:626 rumble strip.jpg|left|225px]]<br />
{| style="padding:0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right"<br />
|-<br />
|'''Forms'''<br />
|-<br />
|[http://epg.modot.mo.gov/forms/DE-DEForms/DESIGN%20EXCEPTION%20INFORMATION.dot Design Exception Information Form]<br />
|-<br />
|[[media:232.2 Passing Lane Special Sheet.pdf|Passing Lane Special Sheet]]<br />
|}<br />
<br />
Rumble strips are a grooved pattern in the pavement that make road travel safer for motorized vehicles. The grooves alert drivers by causing the vehicle’s wheels to noisily and suddenly vibrate when it leaves the driving lane. <br />
<br />
This article deals with both edgeline and centerline rumble strips as well as the [[626.3 Construction Inspection Guidelines for Sec 626|construction inspection guidelines]] that must be considered to achieve a high-quality product. Guidance is also presented for [[626.4 Transverse Rumble Strips|transverse rumble strips]], warning devices placed in the driving lane.<br />
<br />
'''District Responsibility.''' A higher level of collaboration with the Traffic and Design Divisions of Central Office is necessary prior to a District Engineer’s approval of a design exception to omit or modify systemwide safety improvements (such as rumble strips) on a project. <br />
<br />
It is the district's responsibility to re-install obliterated or deteriorated rumble strips.<br />
<br />
==626.1 Edgeline Rumble Strips==<br />
[[image:626 Edgeline Rumble Strips.jpg|right|350px|thumb|<center>'''Edgeline Rumble Strips'''</center>]]<br />
<br />
Edgeline rumble strips are used to enhance [http://www.modot.mo.gov/safety safety] on every [[231.4 Shoulder Width|shoulder]] at least 2 ft. wide, unless the shoulder has a curbed section or is intended to be used as a future travel lane. Rumble strips are omitted where the posted speed is less than 50 mph. All [http://epg.modot.mo.gov/files/7/72/232_Major_Highways_Map.pdf major roads] will have edgeline rumble strips unless the posted speed is less than 50 mph. In urban areas, edgeline rumble strips may be omitted on major roads with a [[131.1 Design Exception Process|design exception]] (e.g., noise is a significant issue and safety is not a significant issue).<br />
{|style="padding: 0.3em; margin-right:7px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="left" <br />
|-<br />
|'''Rumble Strips'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/Ri01057/RDT03007.pdf Report, 2003]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/ad09153/orb10000.pdf Summary, 2009]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
Edgeline rumble strips may be used on minor roadways as a specific safety countermeasure with a paved shoulder. Where several sections of edgeline rumble strips are installed in close proximity, continuity should be maintained.<br />
<br />
Edgeline rumble strips are to be milled into bituminous and portland cement concrete. Milling has little or no effect on the integrity of the pavement structure and milled rumble strips produce greater noise and vibration than rolled or formed rumble strips. Refer to [http://www.modot.mo.gov/business/standards_and_specs/documents/62600.pdf Standard Plan 626.00] for details. Edgeline rumble strips are omitted between the radius points for side road approaches, entrances and median crossovers. Edgeline rumble strips should be omitted on bridges and on ramps for diamond, single point, partial cloverleaf and similar types of [[:category:234 Interchanges|interchanges]], but may be considered on longer ramps for directional or other large interchanges. The length of edgeline rumble strip installation is to be estimated and pay items provided.<br />
<br />
Edgeline [[:category:620 Pavement Marking|pavement marking]] material is sprayed over the rumble strip, creating what is often called a “rumble stripe.”<br />
<br />
==626.2 Centerline Rumble Strips==<br />
<br />
[[Image:626.2 Centerline Rumble Strip Marking for Two Lane Roadway.jpg|right| 200px|thumb|<center>''' Centerline Rumble Strip Marking for Two-Lane Roadway'''</center>]]<br />
All two-lane [[media:232 Major Highways Map.pdf|major roads]] with new pavement will have centerline rumble strips (see figure at right) unless the posted is less than 50 mph. Centerline rumble strips are provided on all major two-lane roads, and on minor roads with a cross-centerline [http://www.modot.mo.gov/safety/trafficaccidentstatistics.htm accident history]. Rumble strips on a centerline have been shown to reduce head-on crashes by alerting drivers that they are leaving their lane of travel. On roadways with a travelway width of 20 ft., centerline rumble strips become obtrusive and are not recommended.<br />
<br />
[[image:626.2 Passing Lane Centerline Rumble Strip marking.jpg|left| 275px|thumb|<center>'''[[232.2 Passing Lanes|Passing Lane]] Centerline Rumble Strip Marking'''</center>]]<br />
<br />
As with edgeline rumble strips, pavement marking material is sprayed over the centerline rumble strip, creating what is often called a “rumble stripe.” <br />
<br />
Rumble strips in the median of typical passing lane roadways (see [[media:232.2 Passing Lane Special Sheet.pdf|Passing Lanes Special Sheet]]) vary somewhat from centerline rumble strips on typical two-lane roadways (see figure below). Passing lanes can operate effectively with no separation between opposing lanes of travel. While no separation is required, AASHTO guidance recommends that some separation, however small, between the lanes in opposite directions of travel is desirable. Therefore, a flush separation of 4 ft. (1.2 m) between the opposing directions of travel is preferred (see [[media:232.2 Passing Lane Typical Cross Section.pdf|typical section]]), if at all possible.<br />
<br />
[[Image:626.2 Median Rumble Strip passing.gif|right| 500px|thumb|<center>''' Example of a Median Rumble Strip with Passing Lanes'''</center>]]<br />
<br />
In order to maintain the integrity of the rumble strip and the pavement, the pavement material must be either concrete or the final lift of bituminous material must be least 1 3/4 in. thick, and the pavement must have a final asphalt thickness of at least 3 3/4 in. Centerline rumble strips are not to be placed on bridges or within the limits of an intersection with left turn lanes. The limits of the intersection are defined by the beginning of the tapers for the left turn lanes. Centerline rumble strips are not to be placed on any joint. Longitudinal joints shall be offset 10 in. to accommodate the width of the rumble strip. The length of centerline rumble strip installation should be estimated and pay items provided.</div>Jonesjbhttps://epg.modot.org/index.php?title=171.6_Roadsides&diff=27052171.6 Roadsides2012-01-09T18:50:22Z<p>Jonesjb: /* RDS(E10) Clear Zone */ Clarified the resources for establishing and maintaining clear zones.</p>
<hr />
<div>===RDS(A1) Commuter Parking Lots===<br />
Refer to [[:Category:644 Weigh Stations, Rest Areas, Welcome/Information Centers and Commuter Parking Lots|EPG 644 Weigh Stations, Rest Areas, Welcome/Information Centers and Commuter Parking Lots]] for information regarding the design, construction, and maintenance of commuter lots.<br />
<br />
===RDS(A2) Roadside Maintenance Activities by Others===<br />
There are three methods by which non-MoDOT personnel may perform roadside activities on the right of way or on Commission property: by permit, through the [[:Category:824 Adopt-A-Highway and Sponsor-A-Highway Programs|Adopt-A-Highway Program]] and through the Growing Together Program. All of these methods require an agreement between MoDOT and the outside party. <br />
<br />
Neighbors should be allowed to mow (without regard to height) the right of way in front of <br />
their property if they feel it will enhance the appearance of their property. Refer to [[:Category:822 Roadside Vegetation Management|EPG 822 Roadside Vegetation Management]].<br />
<br />
===RDS(A3) Wetland Mitigation Areas===<br />
To ensure compliance with state and federal executive orders requiring no net loss of wetlands, MoDOT is responsible for compensating unavoidable wetland impacts through wetland restoration, creation or enhancement. Signs stating "Mitigation Area - Do Not Disturb" are used to identify the boundaries of the mitigation area to protect against disturbance. Refer to [[127.16 Wetland and Stream Mitigation#127.16.1.4 Maintenance|EPG 127.16.1.4 Maintenance]] concerning maintenance of wetland mitigation areas.<br />
<br />
===RDS(A4) Heritage Database Information (HDI)===<br />
Refer to [[127.27 Guidelines for Obtaining Environmental Clearance for Project Specific Locations|EPG 127.27 Guidelines for Obtaining Environmental Clearance for Project Specific Locations]].<br />
<br />
===RDS(A5) Underground Utilities===<br />
Utility companies with underground utilities on highway right of way shall be informed when work is planned that will cause a substantial change in grade at the location of the utility. This may involve work such as major slide repair, major slope grading or drainage channel clean out or realignment. (Although [[:Category:142 Missouri One Call System|One Call]] should be notified, this action alone does not ensure all utilities will be notified).<br />
<br />
==171.6.1 Programs==<br />
<br />
===RDS(B1) [[:Category:824 Adopt-A-Highway and Sponsor-A-Highway Programs|Adopt-A-Highway]]===<br />
MoDOT establishes and maintains an ongoing cooperative program that encourages individuals, groups and organizations to become involved in litter pickup, mowing and/or beautification of roadside areas. Refer to [[:Category:824 Adopt-A-Highway and Sponsor-A-Highway Programs|EPG 824 Adopt-A-Highway and Sponsor-A-Highway Programs]] for additional information and guidance. <br />
<br />
See [http://www.sos.mo.gov/adrules/csr/current/7csr/7c10-14.pdf 7 CSR 10-14.010 - 14.050, Adopt-A-Highway Program].<br />
<br />
===RDS(B2) Deer Kill Reports===<br />
Each road killed deer encountered is to be recorded on the Deer Death Report at the district office. This monthly report is sent to the Central Office and the monthly total reported to the Missouri Department of Conservation. <br />
<br />
===RDS(B3) Growing Together Program===<br />
MoDOT cooperates with state and local government groups as well as private groups interested in developing extensive plantings on right of way designed to enhance the appearance of state highways and neighboring communities. Contact the [http://wwwi/maintenance/Roadsidesdefault.htm Roadside Section] in the Central Office for assistance. <br />
<br />
===RDS(B4) Incarcerated Personnel===<br />
Incarcerated personnel are used to improve the roadside environment by undertaking work that is above and beyond normal highway beautification efforts. The intent is to accomplish labor intensive projects not normally accomplished by routine maintenance crews or construction contracts. Refer to [[:Category:823 Incarcerated Personnel Work Release Program|EPG 823 Incarcerated Personnel Work Release Program]] for information.<br />
<br />
==171.6.2 Rest Areas and Roadside Parks==<br />
===RDS(C1) Dispensing Free Refreshments===<br />
Groups and organizations are permitted to use rest areas and roadside parks to dispense coffee and other nonalcoholic refreshments for the sole purpose of encouraging motorists to take safety breaks during a holiday trip. <br />
<br />
All activities must be confined within the rest area or park boundary and away from drives <br />
and ramps used for the movement of vehicles. Signing for this activity is provided by <br />
MoDOT and organization signs are limited to a small identification sign at the table or <br />
vehicle used to dispense refreshments.<br />
<br />
Refreshments offered to the traveling public must be free. Donations and contributions for any cause shall not be permitted.<br />
<br />
===RDS(C2) Rest Area Drinking Water===<br />
Refer to [[127.25 Maintenance Environmental Policies#127.25.3.2 Rest Area Drinking Water|EPG 127.25.3.2 Rest Area Drinking Water]] concerning information about rest area drinking waters.<br />
<br />
===RDS(C3) Rest Area Sewage Control===<br />
Refer to [[127.25 Maintenance Environmental Policies#127.25.3.1 Rest Area Lagoon|EPG 127.25.3.1 Rest Area Lagoon]] concerning information about rest area lagoons. <br />
<br />
===RDS(C4) Roadside Park Requirements===<br />
State highway right of way cannot be used for roadside park purposes. Roadside parks are not planned as local parks or overnight camping areas and are not built with toilets, water or electrical supply. <br />
<br />
All roadside parks must be approved by the Commission.<br />
<br />
===RDS(C5) Vending===<br />
No vending is allowed in rest areas or on state highway right of way except for vending machines installed by agreement or permit. By law, the Department of Social Services, Division of Family Services, Rehabilitation Services for the Blind has been granted authority to govern and regulate vending in rest areas. When such authority is declined, MoDOT shall develop an agreement or issue a permit with another appropriate agency, organization or association to govern and regulate the vending. <br />
<br />
If the Department of Social Services, Division of Family Services, Rehabilitation Services for the Blind elects to assume the authority granted by law to govern and regulate vending assigned to another agency, organization or association, the existing agreements or permits shall be terminated.<br />
<br />
MoDOT reserves the right to remove any vending machine from a rest area at vendors cost, if the machine is installed or maintained in violation of established agreements.<br />
<br />
==171.6.3 Structures==<br />
<br />
===RDS(D1) [[:Category:140 Encroachments and Items Permitted on MoDOT’s Right of Way|Right of Way Encroachments]]===<br />
State law allows the commission to prohibit encroachments on state right of way. Right of way encroachment is defined as the placement and/or maintenance of unauthorized items, or the performance of unauthorized activities, on or extending over onto state right of way. Unauthorized items and activities include but are not limited to:<br />
<br />
:{|<br />
|-<br />
!align="center"|Items|| !!align="center"|Activities<br />
|-<br />
|Signs (political, garage sale, etc.)|| ||Vehicle parking in restricted areas<br />
|-<br />
|Display materials (streamers, balloons, banners)|| ||Vending<br />
|-<br />
|Trash containers|| ||Excavation<br />
|-<br />
|Fences || ||Construction<br />
|}<br />
<br />
All encroachments that pose a safety hazard to MoDOT personnel or the traveling public shall be addressed immediately. If the encroachment posing a safety hazard is an unauthorized item or activity and can be removed, it shall be removed immediately. <br />
<br />
Unauthorized encroachment items removed from the right of way should be stored at the <br />
nearest maintenance facility; unclaimed items may be properly disposed after 30 days.<br />
<br />
For permanent encroachments involving construction on the right of way, a written notice shall be sent to the owner by the district engineer. If the encroachment is not removed in a timely manner, a “Notice to Remove Encroachment,” including a deadline for removal shall be sent to the owner by the district engineer. If the encroachment is not removed by the specified deadline, the district engineer shall refer the matter to the [http://wwwi/intranet/cc/modot.asp?nav= Chief Counsel’s Office] for legal action. Sample encroachment notice letters and encroachment removal letters are available from the State Maintenance Engineer.<br />
<br />
Permanent encroachments where the owner cannot be identified shall be removed as soon as possible.<br />
<br />
Encroachments that do not pose an immediate safety hazard to MoDOT personnel or the traveling public shall be removed prior to beginning a maintenance activity on the route. However, encroachments may be removed more frequently at the discretion of the [http://www.modot.org/bolderfiveyeardirection/documents/FINAL_AEonepagesummary.pdf Area Engineer]. Encroachment removals can be coordinated with litter pickup and other maintenance work such as mowing, edge-rut repairs, crack sealing, etc.<br />
<br />
Single-use items generally made of paper and cardboard can be disposed of immediately without notice. Professionally made or reusable items should be stored at the nearest maintenance facility; unclaimed items may be properly disposed after 30 days.<br />
<br />
Any holiday decorations placed on or across the state right of way must have a permit signed by personnel designated by the district engineer.<br />
<br />
All actions regarding encroachments should be timely and fair. <br />
<br />
[http://wwwi/maintenance/library/policies/Notice%20of%20Encroachment.pdf Notice of Encroachment RDS(D1)A]<br />
<br />
[http://wwwi/maintenance/library/policies/Notice%20to%20Remove%20Encroachment.pdf Removal Notice RDS(D1)B]<br />
<br />
[http://wwwi/maintenance/library/policies/Unauthorized%20Items%20off%20Roadsides%20Flier.pdf Unauthorized Items off Roadsides Flier]<br />
<br />
===[[:Category:140 Encroachments and Items Permitted on MoDOT’s Right of Way#140.2 Monuments, Maintenance Policy RDS(D2)|RDS(D2) Monuments]]===<br />
MoDOT permits approved organizations (State Historical Society of Missouri, Federated Garden Clubs of Missouri and the Daughter's of the American Revolution) to place markers at approved locations along highways within the bounds of rest areas, roadside parks or turnouts. These markers are located for the purpose of honoring service men and women who served in a particular war or to designate points of historical interest. <br />
<br />
Placement of markers and tablets requires Commission approval.<br />
<br />
Additional information is available from the [http://wwwi/maintenance/Roadsidesdefault.htm Roadside Section] in the Central Office.<br />
<br />
==171.6.4 Vegetation Management==<br />
<br />
===RDS(E1) Billboard Visibility===<br />
Refer to [[236.16 Outdoor Advertising#236.16.8 Vegetation Removal|EPG 236.16.8 Vegetation Removal]] concerning the management of vegetation around billboards. <br />
<br />
===RDS(E2) Crops on Right of Way===<br />
Refer to [[822.8 Hay and Other Crops on the Right of Way|EPG 822.8 Hay and Other Crops on the Right of Way]]. <br />
<br />
===RDS(E3) Hay Harvesting on Right of Way===<br />
Refer to [[822.8 Hay and Other Crops on the Right of Way|EPG 822.8 Hay and Other Crops on the Right of Way]].<br />
<br />
===RDS(E4) Herbicides===<br />
Refer to [[:Category:821 Herbicides and Roadsides|EPG 821 Herbicides and Roadsides]]. <br />
<br />
===RDS(E5) Mowing===<br />
Refer to [[:Category:822 Roadside Vegetation Management|EPG 822 Roadside Vegetation Management]].<br />
<br />
===RDS(E6) Noxious Weed Control===<br />
Refer to [[821.18 Noxious Weeds|EPG 821.18 Noxious Weeds]]. <br />
<br />
===RDS(E7) Plant Collection from Right of Way===<br />
No person shall dig or remove any plants or plant parts from any real property of the Commission or the right of way of any state highway or roadway without permission. Special permits covering the collection of plants and plant parts from highway right of way may be issued by MoDOT. Provided that such plants or plant parts are not offered for sale, the collection of seeds, fruits, nuts, berries, edible wild greens or flowering parts of plants, or the occasional collection of plants for the purposes of scientific research or education may be permitted. <br />
<br />
Under special circumstances, MoDOT can write a permit, to collect and sell plants or plant parts from right of way. Contact the [http://wwwi/maintenance/Roadsidesdefault. Roadside Section] for information. <br />
<br />
===RDS(E8) Roadside Burning===<br />
Refer to [[127.25 Maintenance Environmental Policies#127.25.8.1 Open Burning|EPG 127.25.8.1 Open Burning]] for information pertaining to the open burning of materials on MHTC property. <br />
<br />
===RDS(E9) [[822.11 Maintenance Planning Guidelines for Tree Removal|Tree Removal]]===<br />
Trees located on Missouri Highways and Transportation Commission (MHTC) property are considered state property. Trees on MHTC property that are dead, diseased, deformed or storm damaged, have the potential to create a safety hazard to MHTC personnel as well as the traveling public. Efforts should be made to minimize the potential hazard. <br />
<br />
Utility companies should be contacted prior to removing trees under or near utility lines, for possible assistance or removal by their crews. Commercial arborists may be obtained on an agreed price basis for removal of large trees especially where there is a possibility of damage to private property.<br />
<br />
Tree trunks and tree limbs may be cut up by department personnel and hauled back to the maintenance building for use as firewood at the maintenance building, or stockpiled at the maintenance site, and ultimately sold per General Services policies concerning the disposal of surplus property. A copy of the [http://wwwi/maintenance/library/policies/Firewood%20Bill%20of%20Sale.pdf “Bill of Sale”] for the tree trunks and tree limbs sold as surplus property shall be maintained by MoDOT in accordance with the policies pertaining to surplus property disposal.<br />
<br />
Tree trunks and tree limbs may be cut into manageable lengths (not less than 2 ft. long and not more than 6 ft. long) and left on the adjacent property owners property at the right of way line for use by the adjacent property owner provided the adjacent property owner has expressed a desire to use the wood. The adjacent property owner shall obtain access to the wood from their own property. The adjacent property owner shall not utilize MHTC right of way to gain access to the wood.<br />
<br />
Root-balls associated with tree removals are not considered to be clean fill according to the Missouri Department of Natural Resources. Therefore, root-balls shall not be buried. They may be hauled off to a demolition landfill, or they may be ground up using a tub grinder.<br />
<br />
Any burning of tree trunks, tree limbs, or root-balls on the right of way shall be done <br />
according to the [[127.25 Maintenance Environmental Policies#127.25.8.1 Open Burning|EPG 127.25.8.1 Open Burning]].<br />
<br />
Tree stumps anywhere on the right of way shall be cut flush or below ground level. Treatment of tree stumps to prevent re-growth shall be in accordance with [[:Category:821 Herbicides and Roadsides|EPG 821 Herbicides and Roadsides]].<br />
<br />
Personnel engaged in the removal of dead, diseased, deformed, or storm damaged, trees shall be trained in the safe operation of chainsaws and other tree trimming devices. <br />
<br />
Personnel must also be familiar with the applicable safety guidelines as set forth in <br />
[http://lnapp1/RI/RIManual.NSF/SHToC?OpenView MoDOT's Safety Policies, Rules & Regulations].<br />
<br />
MoDOT staff shall be in compliance with Personnel Policy # 2700 – Ethical Conduct when disposing of tree trunks and tree limbs. Also, staff should comply with the U.S. Fish and Wildlife Service concerning protection of Indiana bat tree habitat. Questions regarding Indiana bat trees should be directed to [http://wwwi/design/units/enviromental.htm the Environmental Section] of Design.<br />
<br />
Trees associated with construction projects shall be managed according to the conditions <br />
contained in the contract documents.<br />
<br />
===RDS(E10) Clear Zone===<br />
Refer to [[231.2 Clear Zones|EPG 231.2 Clear Zones]] for information concerning how clear zones are established and [[120.6 Roadsides#120.6.2 Trees and Brush|EPG 120.6.2 Trees and Brush]] concerning their maintenance.<br />
<br />
===RDS(E11) National Forest Lands===<br />
MoDOT shall coordinate with the Forest Service all maintenance activities which involve additional clearing, slash disposal, chemical control of vegetation, disposal of slough material, changes in road drainage patterns, materials source and storage and similar actions which involve highways through National Forest lands. The Forest Service will assist MoDOT with matters related to equipment parking, material storage, material sources, and designated slough and slide material disposal areas as well as advising the department of any activities that have an impact on highway maintenance.<br />
<br />
[[category:171 Maintenance Policy and Operations|171.06]]</div>Jonesjbhttps://epg.modot.org/index.php?title=120.6_Roadsides&diff=27051120.6 Roadsides2012-01-09T18:31:15Z<p>Jonesjb: /* Performance Objectives */ Changes the zone of hardscape prohibition from the static 30 ft. to the more inclusive 'clear zone.'</p>
<hr />
<div>[[image:120.6.jpg|center|800px]]<br />
<br />
==120.6.1 [[:Category:822 Roadside Vegetation Management|Mowing]] and Turf Conditions==<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#ffddcc" width="210px" align="right" <br />
|-<br />
|'''Mowing Practices and Fleet Size'''<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/ad09079/orb09004.pdf Summary 2009]<br />
|-<br />
|[http://library.modot.mo.gov/RDT/reports/ad09079/adv09005.pdf Summary 2009]<br />
|-<br />
|'''See also:''' [http://www.modot.gov/services/OR/byDate.htm Innovation Library]<br />
|}<br />
<br />
===Performance Expectation===<br />
Vegetation height should be maintained between 6 and 12 inches in fully developed areas and between 6 and 18 inches in undeveloped areas. Slopes greater than 1V:3H (3:1) shall not be mowed unless in urban areas with the proper equipment. Transitions between areas shall be gradual and natural. Chemical and/or mechanical trimming should be done as needed so that vegetation height around signposts, delineators, guardrail, guard cable, etc. is consistent with the mowing height.<br />
<br />
===Performance Measures===<br />
Visual inspections will be conducted on randomly selected tenth-mile segments in the fall to determine if the right of way is being maintained in accordance with the vegetation management policy.<br />
<br />
===Performance Objectives===<br />
Vegetation control may be completed up to at least 30 ft. from the edge of the nearest traveled way with 90% of the areas around objects trimmed or sprayed. 95% of unpaved areas should have proper vegetative cover, not including rock cuts or fill areas constructed predominately of rock. 100% of the right of way should be clear or treated to control noxious weed growth.<br />
<br />
{| align="center"<br />
|-<br />
|[[image:120.6.1.1.jpg|350px|thumb|<center>'''Good'''</center>]]||[[image:120.6.1.2.jpg|350px|thumb|<center>'''Poor'''</center>]]<br />
|}<br />
<br />
<br />
==120.6.2 [[822.11 Maintenance Planning Guidelines for Tree Removal|Trees]] and [[822.10 Maintenance Planning Guidelines for Brush Cutting|Brush]]==<br />
<br />
===Performance Expectation===<br />
Roadside vegetation shall be maintained to provide a safe clear zone, adequate sight distance and visibility of roadside marking and delineation.<br />
<br />
===Performance Measures===<br />
Visual inspections will be conducted on randomly selected tenth-mile segments in the spring to determine the extent of the encroachments of trees and brush within the clear zone.<br />
<br />
===Performance Objectives===<br />
No tree with a diameter greater than 4 in. at breast height or hardscape shall be within the clear zone as defined in [[231.2 Clear Zones|231.2]], unless shielded by guardrail. All of the right of way shall be free of hazardous, leaning, or dead trees capable of falling onto the roadway. All signs shall be visible for a distance of 500 ft. on the mainline and 250 ft. on the ramps.<br />
<br />
{| align="center"<br />
|-<br />
|[[image:120.6.2.1.jpg|350px|thumb|<center>'''Good'''</center>]]||[[image:120.6.2.2.jpg|350px|thumb|<center>'''Poor'''</center>]]<br />
|}<br />
<br />
==120.6.3 Debris and Road Kill==<br />
<br />
===Performance Expectation===<br />
Debris and road kill shall be removed from the roadway, shoulders and roadsides to provide a safe road and an attractive roadside. It shall be removed as soon as possible if located on the roadway or a ramp. Debris on the shoulders and within the clear zone shall be removed within 48 hours of notification.<br />
<br />
===Performance Measures===<br />
Visual inspections will be conducted on randomly selected tenth-mile segments in the spring and fall to determine number of pieces of debris or road kill present.<br />
<br />
===Performance Objectives===<br />
No findings of debris or road kill within the clear zone.<br />
<br />
{| align="center"<br />
|-<br />
|[[image:120.6.3.1.jpg|350px|thumb|<center>'''Good'''</center>]]||[[image:120.6.3.2.jpg|350px|thumb|<center>'''Poor'''</center>]]<br />
|}<br />
<br />
<br />
==120.6.4 [[824.1 Maintenance Planning Guidelines for Litter Pick-Up|Litter]]==<br />
<br />
===Performance Expectation===<br />
Litter should be removed from the roadway, shoulders and roadsides in order to provide an attractive roadside. Visible litter should be removed prior to each mowing cycle.<br />
<br />
===Performance Measures===<br />
Visual inspections will be conducted on randomly selected tenth-mile segments in the spring and fall to determine the amount of litter present.<br />
<br />
===Performance Objectives===<br />
The total amount of litter or debris shall not exceed one five-gallon bucket.<br />
<br />
<br />
{| align="center"<br />
|-<br />
|[[image:120.6.4.1.jpg|350px|thumb|<center>'''Good'''</center>]]||[[image:120.6.4.2.jpg|350px|thumb|<center>'''Poor'''</center>]]<br />
|}<br />
<br />
<br />
==120.6.5 [[:Category:808 Planting Trees, Shrubs, and Other Plants#808.2 Maintenance Planning Guidelines for Landscaping|Landscape Beds]]==<br />
<br />
===Performance Expectation===<br />
Landscape beds should have a neat and well-maintained appearance overall. Vegetation should be healthy and attractive and not pose a safety concern. Maintenance by other organizations is preferred and encouraged.<br />
<br />
===Performance Measures===<br />
Visual inspections will be conducted on randomly selected interchanges in the fall to determine if the landscape beds look good and are not creating a safety hazard.<br />
<br />
===Performance Objectives===<br />
80% of the vegetation is healthy, well maintained and does not pose a safety hazard.<br />
<br />
{| align="center"<br />
|-<br />
|[[image:120.6.5.1.jpg|350px|thumb|<center>'''Good'''</center>]]||[[image:120.6.5.2.jpg|350px|thumb|<center>'''Poor'''</center>]]<br />
|}<br />
<br />
[[Category:120 Interstate Maintenance Expectations|120.6]]</div>Jonesjbhttps://epg.modot.org/index.php?title=902.18_Glossary&diff=27048902.18 Glossary2012-01-09T16:55:54Z<p>Jonesjb: Clarified definition of 'Clear Zone' to more accurately reflect the AASHTO definition.</p>
<hr />
<div>[[image:902.12.jpg|right|400px]]<br />
'''85th Percentile Speed''' - The speed at which 85% of the traffic is traveling at or below. <br />
<br />
'''AASHTO''' - American Association of State Highway and Transportation Officials. A national organization that develops guidelines, specifications, policies, and standards for transportation design, construction and operation. <br />
<br />
'''Acceptance Test Period''' - Time period in which the acceptance of and payment for a new device is delayed pending satisfactory performance. <br />
<br />
'''Actuated''' - Indications controlled by vehicle or pedestrian detection. Also refer to Semi-Actuated and Full-Actuated. <br />
<br />
'''Actuated, Fully-''' - All indications at a signal controlled by detection. <br />
<br />
'''Actuated, Semi-''' - Some, but not all, indications at a signal controlled by detection. <br />
<br />
'''Actuation''' - The action of a vehicle or pedestrian causing a detector to create a call in that phase or movement to request right of way.<br />
<br />
'''Adaptive Split Control''' - A means of local intersection split selection based on vehicular activity. <br />
<br />
'''Added Initial''' - An increment of time added to the minimum initial portion in response to vehicle actuation. <br />
<br />
'''Address''' - The identification of specific intersections for transmission of commands or the receipt of data. <br />
<br />
'''Advance Call Detector''' - A detector located a considerable distance ahead of an intersection which calls the green to that approach. <br />
<br />
'''Advance Warning''' - A per movement output used to give advance notice of an upcoming yellow or red indication. Typically used at hidden intersections with “prepare to stop” indicators. <br />
<br />
'''Agreement''' - A concord of understanding and intention between two or more parties that addresses the rights and responsibilities of each party. <br />
<br />
'''Algorithm''' - A procedure, process, or rule for the solution of a problem. An algorithm may be a set of computational rules for the solution of a mathematically expressed problem. <br />
<br />
'''All Red''' - (1) An optional feature in intersection controls which provides adjustable time intervals for a red clearance interval following any yellow clearance interval. (2) All red flashing intersection signalization used during normal control off periods. <br />
<br />
'''Amplifier (Detector)''' - An electrical device used to sense electrical load changes on associated sensing equipment (e.g. inductive loops) and provide an output to an intersection controller for vehicle detection. <br />
<br />
'''Approach''' - Section of roadway in advance of an intersection. The remaining traffic lanes minus any exclusive turns or parking lanes. <br />
<br />
'''Arterial''' - A main street generally considered to be a thoroughfare with preferential right of way. <br />
<br />
'''Asynchronous''' - A non-synchronized condition. Free running without any specific relationship in operation to any other condition. <br />
<br />
'''Attestation''' - The act of witnessing an instrument in writing and recording the name of the witness. <br />
<br />
'''Auto/Manual Switch''' - A cabinet switch, when operated, discontinues normal signal operation and permits manual operation. <br />
<br />
'''Average Day''' - The day that best represents the normal flow of traffic. <br />
<br />
'''Background Cycle''' - Cycle length run at the master controller that, once at the start of the cycle, outputs the system reference to the local controllers. May also be run at a controller operating TBC, which supervises the actuated operation of the intersection. <br />
<br />
'''Back Panel''' - A board within the controller cabinet upon which are mounted field terminals, fuse receptacles or circuit breakers, and other portions of the controller assembly not included in the controller unit or auxiliary devices. <br />
<br />
'''Backplate''' - A strip of thin material extending outward parallel to the signal face on all sides of a signal housing to provide a suitable background for the signal indications. <br />
<br />
'''Band (Green Band)''' - Through or green elapsed time between the first and last possible vehicle permitted through an intersection on a progressive coordination system. <br />
<br />
'''Barrier (Compatibility Line)''' - A reference point in the preferred sequence of a dual-ring controller at which both rings are interlocked. Both rings cross the barrier simultaneously to select and time phases on the other side. <br />
<br />
'''Basic Lighting''' - Roadway lighting provided only at potential conflict areas of an intersection or interchange <br />
<br />
'''Baud Rate''' - The input rate of data transmission to a communications channel, usually expressed in bits per second. <br />
<br />
'''Buffer''' - A device used to make two other devices or systems compatible, in particular, a device or routine that compensates for differences in times of occupance or rates of flow when data is transmitted between devices. <br />
<br />
'''Buss Interface Unit (BIU)''' - A device in a controller cabinet that converts analog inputs to serial communications data and serial data to analog outputs to interface with various cabinet components. <br />
<br />
'''Cabinet''' - An outdoor enclosure for housing the controller unit and associated equipment. <br />
<br />
'''Call''' - A registration of a demand by a vehicle or pedestrian for right of way at a controller unit. <br />
<br />
'''Calling Detector''' - A detector installed in a selected location to detect vehicles which may not otherwise be detected, and whose output may be modified by the controller unit. When the signal is green, the detector is disconnected so that extensions of the green can come only from the detector located upstream of the calling detector. <br />
<br />
'''Capacity''' - The maximum rate of flow at which persons or vehicles can be reasonably expected to traverse a point or uniform segment of a lane or roadway during a specified time period under prevailing roadway, traffic, and control conditions, usually expressed as vehicles per hour or persons per hour. <br />
<br />
'''Carrier Frequency''' - A single frequency that is modulated by the lower frequency signals being communicated or carried, each carrier frequency provides an independent communications channel. <br />
<br />
'''Cars Waiting''' - Also known as a Queue. Term used in sophisticated volume-density controls to apply more stringent requirements to traffic having the right of way based on the number of vehicles waiting in a conflicting movement. (Also see Time Waiting). <br />
<br />
'''Change Interval''' - The "yellow" plus "all red" intervals that occur between phases of a traffic signal to provide for clearance of the intersection before conflicting movements are released. <br />
<br />
'''Channelization''' - Physical separation of traffic movements by positive barrier or markings. <br />
<br />
'''[[231.2 Clear Zones|Clear Zone]]''' - An unobstructed, traversable area provided beyond the edge of the through traveled way for the recovery of errant vehicles. <br />
<br />
'''Clearance Interval''' - The "all red" interval that permits traffic to clear the intersection before conflicting traffic movements are released. <br />
<br />
'''Closed Loop System''' - Coordinated signal system that allows for remote access and data communication to and from all controllers within the system via the master controller. <br />
<br />
'''Collision Diagram''' - Symbolic representation of number and type of crashes occurring in an area. <br />
<br />
'''Combination Lane''' - See Shared Lane. <br />
[[image:902.12 Commission.jpg|right|300px|thumb|<center>'''Missouri Highway and Transportation Commission'''</center>]]<br />
'''Commission''' - Missouri Highway and Transportation Commission, a group appointed by the governor of Missouri to oversee MoDOT operations. The term may also indicate MoDOT as a whole. <br />
<br />
'''Compatibility Line''' - The dividing line crossing both rings, in dual ring operation, that separates compatible phase combinations. Usually it divides phases associated with North/ South versus East/West. <br />
<br />
'''Conditional Service''' - A dual-ring feature which allows re-service to an odd phase (left turn) once the opposing through phase has gapped out. The service is conditioned by the time remaining in the adjacent through phase’s MAX time. <br />
<br />
'''Conduit''' - Pipe used to house stretches of cable. <br />
<br />
'''Conflict Monitor''' - A device used to continually check for the presence of conflicting signal indications and other malfunctions and to provide an output in response to conflict or malfunction. <br />
<br />
'''Conflict Monitor Program Card''' - Card on which compatible movements, or channels, are programmed for use with the conflict monitor. <br />
<br />
'''Conflicting Phases''' - Two or more traffic phases which cause interfering traffic movements if operated concurrently. <br />
<br />
'''Continuous-Presence Mode''' - A mode in which the detector output continues if any vehicle (first or last remaining) remains in the field of influence. <br />
<br />
'''Contract''' - A concord of understanding and intention between two or more parties that addresses the rights and responsibilities of each party. <br />
<br />
'''Controller''' - The portion of a controller assembly that is devoted to the selection and timing of signal displays. <br />
<br />
'''Controller Assembly''' - A complete electrical mechanism mounted in a cabinet for controlling the operation of a traffic control signal. <br />
<br />
'''Coordinated Phase(s)''' - The phase(s) designated under coordinated operation to allow for the platoon to proceed through the intersection. <br />
<br />
'''Coordinated System''' - Set of interconnected signals in an area of intersecting roads that provides for coordinated flow in more than one direction on different roads. <br />
<br />
'''Coordination''' - The establishment of a definite timing relationship between adjacent traffic signals. <br />
<br />
'''Critical Intersection(s)''' - The intersection(s) in a coordinated system which is most congested. <br />
<br />
'''Crosstalk''' - The adverse interaction of any channel of a detector unit with any other detector channel in that unit or another unit. It is the mutual coupling of magnetic fields that produces an interaction between two or more detector units in the same cabinet when the units are operating at similar frequencies. Crosstalk results in a detector outputting an actuation in the absence of a vehicle. <br />
<br />
'''Crosswalk''' - The marked crossing area for pedestrians crossing the street at an intersection or designated mid-block location. <br />
<br />
'''Cycle''' - Any complete sequence of signal indications. <br />
<br />
'''D-Plug''' - Plug which attaches to the controller from the interconnect panel and provides for the reception and/or transmission of interconnect and pre-emption signals. <br />
<br />
'''Dallas Left Turn Phasing''' – Left turn phasing option which uses a visibly-limited exclusive indication to display a circular green.<br />
<br />
'''Delay''' - Additional travel time experienced by a driver, passenger, or pedestrian beyond what would reasonably be desired for a given trip. <br />
<br />
'''Delay (Stopped)''' - Time lost by vehicles due to being stopped by a traffic control device. <br />
<br />
'''Demand Control''' - A mode of operation in which the service provided at an intersection reflects the presence of demand for that service often without regard for background cycling. <br />
<br />
'''Density''' - Signifies the number of vehicles in a given distance such as vehicles per mile. Density = volume divided by speed. <br />
<br />
'''Density Control''' - An advanced actuated model of detection that can count waiting vehicles beyond the first vehicle. <br />
<br />
'''Detection''' - The process used to identify the presence or passage of a vehicle at a specific point or to identify the presence of one or more vehicles or pedestrians in a specific area. <br />
<br />
'''Detection Zone''' - The area of the roadway within which a vehicle will be detected by a vehicle detector. <br />
<br />
'''Detector''' - An electrical or electronic device which when actuated signifies the passing or presence of a vehicle or pedestrian desiring the right of way. (See specific detectors: vehicle or pedestrian. <br />
<br />
'''Detector Amplifier''' - A device that is capable of intensifying the electrical energy produced by a sensor. An example is a magnetic detector amplifier. A loop detector unit is commonly called an amplifier, although its electronic function actually is different. <br />
<br />
'''Detector Failures''' - The occurrence of detector malfunctions, such as non-operation, chattering, or other erroneous signaling as well as occupancy errors and false alarms. <br />
<br />
'''Detector Memory (On)''' - The retention of an actuation for future utilization by the controller assembly. <br />
<br />
'''Detector Unit''' - The portion of a detector system other than the sensor and lead-in cable, consisting of an electronic assembly. <br />
<br />
'''Diagnostics''' - A program that facilitates computer maintenance by detection and isolation of malfunctions or mistakes. <br />
<br />
'''[[234.2 Diamond Interchanges|Diamond Interchange]]''' - Freeway interchange where the four entrances and exit ramps to and from the freeway run directly into the intersecting roadway. The four ramps form a diamond pattern with the intersecting roadways. <br />
<br />
'''Digital Timing''' - Pertaining to a method of timing that operates by counting discrete units. <br />
<br />
'''Dilemma Zone''' - Area approaching an intersection where a driver first sees a yellow indication, but is too far away to proceed through the intersection, and is too close to stop comfortably. <br />
<br />
'''Dimming''' - This feature allows selected signal indication to be dimmed during night time operation. <br />
<br />
'''Doppler Effect''' - A change in the frequency with which waves from a given source reach an observer, when the source and the observer are in rapid motion with respect to each other, by which the frequency increases or decreases according to the speed at which the distance is decreasing or increasing. <br />
<br />
'''Downstream''' - The direction to which traffic is flowing. <br />
<br />
'''Dual Entry''' - A mode of operation (in a dual-ring controller unit) in which one phase in each ring must be in service. If a call does not exist in a ring when it crosses the barrier, a phase is selected in the ring to be activated by the controller in a predetermined manner. <br />
<br />
'''Dual Left Turns''' - Two left turn movements on the same approach. <br />
<br />
'''Dual-Ring Controller Unit''' - A controller unit containing two interlocking rings which are arranged to time in a preferred sequence and to allow concurrent timing of both rings, subject to the restraint of the compatibility line (barrier). <br />
<br />
'''Dummy Phase''' - Phase programmed in a controller which does not directly control traffic by changing signal indications, but allows for other phases or overlaps to time out during its time. <br />
<br />
'''Duplex''' - Two-way communication over a single communication link. <br />
<br />
'''Dwell''' - A steady indication whereby no timing device is in control of the time the signal will be illuminated. Usually the condition where no traffic exists to place a request for right of way. Applicable to traffic actuated equipment and normally assigned to the artery. <br />
<br />
'''Easement''' - Agreement between MoDOT and property owner to allow MoDOT to construct or maintain roadway facilities off of the normal right of way. <br />
<br />
'''Electromechanical Device''' - A device characterized by electrical circuits utilizing relays, step switches, motors, etc. <br />
<br />
'''Electronic Device''' - A device which is characterized by electrical circuits utilizing vacuum tubes, resistors, capacitors, and inductors, and which may include electromechanical and solid-state devices. <br />
<br />
'''Emission''' - Portion of vehicle exhaust considered hazardous to the environment. <br />
<br />
'''Engineering Judgment''' - A decision based on available data and information using engineering knowledge and experience. <br />
<br />
'''Engineering Study''' - An Engineering Study documents the collection and analysis of data for a specific location, a set of locations or an area. The criteria used to determine the data collected and analyzed is based upon engineering judgment and accepted practices. Some sources for accepted practices are: MoDOT Manuals, FHWA and AASHTO Manuals, the MUTCD, the Highway Capacity Manual and publications of ITE, TRB and other organizations with expertise in transportation engineering. <br />
<br />
'''Envelope''' - The glass outer enclosure of an incandescent lamp. The envelope seals the gas around the filament and protects the filament. (not used in document)<br />
<br />
'''Exclusive Movement''' - A movement at a signal that runs without any other movements being allowed to proceed. <br />
<br />
'''Exclusive Pedestrian Phase''' - A traffic phase allocated to pedestrian traffic only, provides a right of way pedestrian indication to the exclusion of all vehicular phases (all red). <br />
<br />
'''Exclusive Turn Lane''' - Lane at an intersection where only one movement is allowed. <br />
<br />
'''Execution of Contract or Execution of Document''' - The performance of all acts (signing, sealing, notarizing, etc.) necessary to render the contract complete. <br />
<br />
'''Extendible Recall''' - A form of recall where the associated pahse will always service MIN green and further green time is subject to detector extension.<br />
<br />
'''Extension (or Passage)''' - The timing interval during the extendible portion that is resettable by each detector actuation. The green right of way of the phase may terminate on expiration of the unit extension time. <br />
<br />
'''Fail Safe''' - A primary safety consideration in equipment and system design. Precludes dangerous signalization when power or equipment malfunctions occur. <br />
<br />
'''Feature''' - The selected functions of equipment which perform other than elementary signalization control. <br />
<br />
'''Feedback''' - A system or circuit path which is provided to verify or limit the response to a command. Provides an indication that a command has been executed properly. <br />
<br />
'''FHWA''' - Federal Highway Administration. A section of the federal government, Department of Transportation, that oversees the nation's highways. <br />
<br />
'''Fiber Optic Cable''' - Cable that transmits data by light instead of electricity through finely woven glass wires. <br />
<br />
'''Field Terminals''' - Devices for connecting wires entering the controller assembly. <br />
<br />
'''Filament''' - The part of an incandescent lamp that produces light. It is constructed of a wire material that converts electricity to light (i.e. tungsten). <br />
<br />
'''Flash Switch''' - A cabinet switch, when operated, discontinues normal operation and causes the flashing of any predetermined combination of signal lights. <br />
<br />
'''Flasher''' - A device used to open and close signal circuits at a repetitive rate. <br />
<br />
'''Flasher (Installations)''' - The equipment, including heads, poles, and supports, that provides a flashing indication for incoming traffic. <br />
<br />
'''Flashing Beacon''' - Single indication flashing circular yellow or red. <br />
<br />
'''Flashing Indication or Beacon''' - An indication that flashes at a rate of neither less than 50 nor more than 60 times per minute. The illuminated period of each flash is not less than one-half and not more than two-thirds of the total cycle. For beacons with more than one section or for traffic signal installations, indications may be flashed alternately. <br />
<br />
'''Flashing Operation''' - Signal plan where indications flash either red or yellow instead of cycling solid red-yellow-green. <br />
<br />
[[902.11 Other Design Aspects of Traffic Signals#902.11.28 Guidelines for Optional Use of the Flashing Yellow Arrow at Signalized Intersections|'''Flashing Yellow Arrow''']] – Signal indication that tells the driver they are allowed to drive in the direction the arrow is pointing (left or right) but are required to wait for an adequate gap in the opposing traffic prior to making their turn.<br />
<br />
'''Force Off''' - A command that will force the termination of the right of way. Used in preemption and coordination. <br />
<br />
'''Free Operation''' - Signal operating in a non-coordinated mode. <br />
<br />
'''Free Right Turn''' - A right turn lane that is separated from the adjacent through and/or left turn movements by a triangular shaped island. <br />
<br />
'''Free Turns''' - Turns that are not under signal or stop control. <br />
<br />
'''Full-Actuated''' - Identifies a type of intersection control with vehicle detector input capability in all phases. <br />
<br />
'''Gap (Passage)''' - The maximum time on volume density timed controllers allotted for vehicles to proceed through the intersection.<br />
<br />
'''Gap, Minimum''' - The lower limit to which the extendable portion or teminating gap may be decreased on volume density time controllers.<br />
<br />
'''Gap-Out''' - Expiration of gap timer that causes advancement of the phasing sequence. <br />
<br />
'''Gap Reduction''' - A feature whereby the "unit extension" or allowed time spacing between successive vehicle actuations on the phase displaying the green in the extendible portion of the interval is reduced. <br />
<br />
'''Gaps''' - Distance or time between two moving vehicles. <br />
<br />
'''Geometrics''' - (see Intersection Geometrics) <br />
<br />
'''Grades''' - Slope of roadway in direction of travel. <br />
<br />
'''Green Band''' - Graphical representation in a time-space diagram that shows the amount of time available to a platoon traveling through a coordinated system. <br />
<br />
'''Guy Cable''' - Steel cable used to anchor signal poles in span-wire installations. <br />
<br />
'''Hardwire Interconnection''' - Interconnection method which uses cable strung between controllers in a signal system to send timing plans, system reference, and other data. <br />
<br />
'''HCM''' - Highway Capacity Manual. Publication by the Transportation Research Board (TRB) <br />
<br />
'''Hertz''' - (Hz) Cycles per second.<br />
<br />
'''Highway Advisory Radio''' - A low powered AM radio transmitter used to inform motorists of local roadway or traffic conditions. <br />
<br />
'''Hold''' - A command that retains the existing right of way. <br />
<br />
'''Inbound''' - The traffic condition wherein an imbalance exists with a heavier flow towards central points. Also described as the a.m. peak period. <br />
<br />
'''Infrared Detector''' - With infrared detectors the detection zone is illuminated with low power infrared light. As vehicles pass in the detection zone, the infrared light is reflected from vehicles and is focused by an optical system onto a sensor matrix. A real time signal processing technique analyzes the received signal and determines the presence of a vehicle. Infrared detectors are two types: Active and Passive. Active infrared detectors are most applicable to stop line presence and approach presence detection. Passive infrared detectors detect moving vehicles only, normally up to 300 ft. from the detector unit. <br />
<br />
'''Inhibit''' - An action or signal that prevents a normal change in the operating sequence of a control. It is used to obtain coordination or other special condition upon command from an external source. <br />
<br />
'''Input File''' - An assembly in a Type 170 controller cabinet that contains input devices such as detector cards, isolators, etc. <br />
<br />
'''Interchange''' - Crossing of two or more roads where grades are separated and connections are provided. <br />
<br />
'''Interconnect''' - Method of communication between controllers that allows for synchronized operation and/or data transfer. <br />
<br />
'''Interconnect Panel''' - Panel mounted inside a signal cabinet which interfaces with the controller and incoming interconnect wire. <br />
<br />
'''Intersection''' - At-grade crossing of two or more roads. <br />
<br />
'''Intersection Geometrics''' - Physical layout of driving surfaces and other features. <br />
<br />
'''Interval''' - The time period allotted to a specific control function. Does not necessarily result in a signal change but does indicate a transfer of control within the unit to another circuit. Initial interval, extension interval, etc. <br />
<br />
'''Interval, Signal''' - A period of time in a signal cycle during which all signal indications remain constant. <br />
<br />
'''Isolated Control''' - Signal not operating in coordinated mode. <br />
<br />
'''ITE''' - Institute of Transportation Engineers. A national organization made up of traffic and transportation engineers primarily focused on traffic engineering. <br />
<br />
'''Jumper Wire''' - Any wire used to electrically connect one point to another. <br />
<br />
'''Lagging Left Turn''' - A protected left turn phase which starts after the beginning of that direction's through phase, or immediately after the completion of that direction's through phase. <br />
<br />
'''Lamp''' - That part of the optical unit which, when energized, electrically provides the optical unit light source. <br />
<br />
'''Lane Reduction''' - Closing of a lane on a multi-lane roadway. <br />
<br />
'''Lane Usage''' - Distribution of vehicle volume by lane or allowable movements in a lane. <br />
<br />
'''Last Car Passage''' - A feature option on many controllers providing full passage time increment for the vehicle crossing the detector after the allowable gap has timed out. <br />
<br />
'''Lead-In Wire''' - (Loop Lead-In) The portion of the loop wire between the physical edge of the loop and the pull box; for a magnetic detector and magnetometer it is the wire runnig from the sensor (probe) to the pull box. <br />
<br />
'''Lead-In Cable''' - (Feeder Cable, Home-Run Cable, Transmission Line) The electrical cable connecting the lead-in wire to the input of the loop detector unit. <br />
<br />
'''Lead-Lag''' - A phasing scheme where opposing leading and lagging left turns are used for a road. This feature makes it possible to reverse the phase sequence on a phase pair basis. When the phase pairs 1-2, 3-4, 5-6 and 7-8 are reversed, the odd phases lag the even phases instead of leading, as normal. <br />
<br />
'''Leading Left Turn''' - A protected left turn phase which starts along with or immediately before that direction's through phase. <br />
<br />
'''Lens, Signal''' - That part of the optical unit through which light from the light source and reflector passes and, in so doing, is redirected into a prescribed pattern and is filtered to a prescribed color. <br />
<div id="level of service (LOS)"></div><br />
'''Level of Service (LOS)''' - A qualitative measure describing operational conditions within a traffic stream; generally described in terms of such factors as speed and travel time, freedom to maneuver, traffic interruptions, comfort and convenience, and safety. The six LOS grades are defined as: <br />
<br />
* A - free flow <br />
<br />
* B - reasonably free flow <br />
<br />
* C - stable flow <br />
<br />
* D - approaching unstable flow <br />
<br />
* E - unstable flow <br />
<br />
* F - forced or breakdown flow <br />
<br />
{| style="margin: 1em auto 1em auto" right<br />
|-<br />
|[[image:902.12 LOS A.jpg|left|thumb|<center>'''LOS A'''</center>|175px]]<br />
||[[image:902.12 LOS B.jpg|left|thumb|<center>'''LOS B'''</center>|175px]]<br />
||[[image:902.12 LOS C.jpg|left|thumb|<center>'''LOS C'''</center>|175px]]<br />
|}<br />
{| style="margin: 1em auto 1em auto" right<br />
|-<br />
|[[image:902.12 LOS D.jpg|left|thumb|<center>'''LOS D'''</center>|175px]]<br />
||[[image:902.12 LOS E.jpg|left|thumb|<center>'''LOS E'''</center>|175px]]<br />
||[[image:902.12 LOS F.jpg|left|thumb|<center>'''LOS F'''</center>|175px]]<br />
|}<br />
<br />
'''Light Center Length (LCL)''' - The dimension from the center of the filament of a light bulb to the tip of the base (including solder on the base eyelet). <br />
<br />
'''Light Emitting Diode''' - An electronic semiconductor device that converts electrical energy to light. <br />
<br />
'''Limited-Presence Mode''' - Operation of a detector where output continues for a limited period of time if vehicles remain in the field of influence. <br />
<br />
'''Liquidated Damages''' - A monetary penalty assessed as part of a contract that penalizes the contractor for late completion or delivery. <br />
<br />
'''Load Switch''' - A device used to switch power to the signal lamps.<br />
<br />
'''Local Controller''' - Controller within a coordinated system that is dependent on the master controller for offset reference and timing plan commands. <br />
<br />
'''Locking Memory''' - Controller setting that "remembers" a vehicle call even if the call from the detector is removed. The vehicle call is locked in the controller's memory until that phase is serviced. <br />
<br />
'''Logic Circuit''' - Electrical circuit that makes additional decisions by comparing inputs. <br />
<br />
'''Loop''' - The sensor element imbedded in a roadway that senses a vehicle's passage or presence. It is field fabricated by laying a continuous wire in a roadway slot that is generally rectangular in shape. <br />
<br />
'''Loop Detector''' - A detector that senses a change in inductance of its inductive <br />
loop sensor by the passage or presence of a vehicle near the sensor. <br />
<br />
'''Loop Detector Unit''' - An electronic device capable of energizing the sensor loop(s), of monitoring the sensor loop(s) inductance and of responding to a predetermined decrease in inductance with an output that indicates the passage or presence of vehicles in the zone of detection. It is the electronics package, exclusive of the loop(s) and lead-in cable. <br />
<br />
'''Louver''' - A device that is used to limit the view of a signal indication. It is usually a vane-type assembly installed in the signal head visor. <br />
<br />
'''Main Street Green (MSG)''' - An electrical signal transmitted from the local controller to the central computer during the period when the local controller is displaying green for the coordinated phase.<br />
<br />
'''Magnetometer Detector''' - A detector that measures the difference in the level of the earth's magnetic forces caused by the passage or presence of a vehicle near its sensor. (not used in article) <br />
<br />
'''Maintenance''' - The upkeep of signal equipment to keep it functioning properly, including prevention, repair, and record keeping. <br />
<br />
'''Major Street''' - Through street with highest level of importance. <br />
<br />
'''Malfunction Management Unit (MMU)''' - A device used to continually check for the presence of conflicting signal indications and other malfunctions and to provide an output in response to conflict or malfunction. <br />
<br />
'''Manual Control''' - (1) The control used by authorized personnel at an intersection to terminate an active phase on the basis of observations of traffic conditions. Does not permit alteration of clearance intervals. (2) Occasionally supplied in master control systems to permit programming by an operator. <br />
<br />
'''Manual Operation''' - The operation of a controller assembly by means of a hand-operated device(s). <br />
<br />
'''Manual Pushbutton''' - An auxiliary device for hand operation of a controller assembly. <br />
<br />
'''Manual Reset''' - A reset by which it is possible to manually establish the offset. <br />
<br />
'''Master''' - A control device for supervising and monitoring a system of secondary (local) controllers, maintaining definite time interrelationships and/or accomplishing other supervisory functions. In the case of traffic responsive operation, the master generally includes computation equipment and recording equipment. <br />
<br />
'''Master Controller''' - Controller within a coordinated system responsible for outputting offset references and timing plans to local controllers. May also serve as a local controller. <br />
<br />
'''Maximum 1 (Max 1)''' - Usually refers to a time limit applied to traffic actuated controls to terminate the right of way and prevent massive delays to opposing vehicles during heavy traffic. Termination by maximum usually results in a recall placement to prevent trapping of vehicles. <br />
<br />
'''Maximum 2 (Max II)''' - An optional feature usually associated with coordination methods. Provides two possible maximum time settings for cycle or right of way interval total time before termination begins. <br />
<br />
'''Maximum Green''' - The maximum green time after an opposing actuation, which may start in the initial (minimum green) portion. <br />
<br />
'''Maximum Initial''' - A feature of Density Control. The maximum amount of initial green that a phase may receive. <br />
<br />
'''Maximum Recall''' - A continuous request for service for maximum green timer on selected phases. <br />
<br />
'''Mercury Relay''' - Relay used to remove power from the load switches when a signal is switched from normal operation to a flashing operation. <br />
<br />
'''Microwave''' - High-frequency radio data transmission option for system interconnection that does not require wires between controllers. <br />
<br />
'''Microwave Detector''' - Microwave energy is beamed toward an area of roadway from an antenna mounted overhead or in a sidefire position on a pole. The antenna is angled toward traffic to create a dopplar effect on the reflected signal. When a vehicle passes through the beam, the energy is reflected to the sensing unit (antenna) at a different frequency. The detector, electronic unit, senses the change in frequency which is an indication of the passage of a vehicle. The operating frequency is usually either K-band (24gHz) or Xband (10gHz). <br />
<br />
'''Mid-Block''' - Location between two intersections. <br />
<br />
'''Minimum Gap''' - The minimum amount of space between cars, measured in seconds, at the end of the time to reduce (TTR) period. <br />
<br />
'''Minimum Green''' - The shortest green time of a phase. <br />
<br />
'''Minimum Recall''' - A continuous request for service for minimum green time on selected phases. <br />
<br />
'''Minor Phase''' - A vehicle movement requiring protection but does not necessarily require full sophistication as provided for other movements at the intersection. <br />
<br />
'''Minor Street''' - Street or entrance intersecting the major street. <br />
<br />
'''MIST''' - Management Information System for Traffic. <br />
<br />
'''Mode''' - (1) In detection, refers to the pulse width generated by a vehicle actuation. (2) Also used to identify certain logic condition in controls that permit predetermined operation. <br />
<br />
'''Module''' - A packaged circuit or device easily removed without tools and contains a specified function. Frequently is duplicated to handle similar functions in different areas such as phase modules, load switch modules, etc. <br />
<br />
'''MOV''' - Metal Oxidized Varistor. Component used for lightning protection. <br />
<br />
'''Movement''' - Term to identify travel direction and the approach of a vehicle at an intersection.<br />
<br />
'''Multiplexer''' - A device that combines signals from several communications sources into one communications line. <br />
<br />
'''Multiway Stop''' - All approaches at an intersection controlled by a STOP sign. <br />
<br />
'''MUTCD''' - Manual on Uniform Traffic Control Devices. Publication issued regularly by the National Committee on Uniform Traffic Control Devices which is used as a standard for traffic control for most public agencies. <br />
<br />
'''NEMA''' - National Electrical Manufacturers Association. Commonly refers to standards for traffic controllers that define requirements covering the following areas: functional, environmental, interface levels and physical characteristics. Objective is to attain compatibility and interchangeability of equipment manufactured in conformance with these standards while providing for the safe installation, operation and performance of the equipment. <br />
<br />
'''Non-Actuated''' - A control type generally in the pretimed category, but can be one phase in any control that does not employ a vehicle call. Right of way timing for the non-actuated phase is fixed regardless of traffic volume except for possible dwell. <br />
<br />
'''Nonlocking Memory''' - A mode of actuated-controller-unit operation that does not require detector memory. <br />
<br />
'''Occupancy''' - Indicate a relationship between the number of vehicles in a roadway as compared with the estimated capacity of the roadway. It is a measurement based upon presence time versus gap time averaged over a time period. <br />
<br />
'''Offset''' - The time difference or interval in seconds or percentage of cycle length between the start of the green indication of the coordinated phase and the system reference signal. <br />
<br />
'''Offset Break''' - See System Reference. <br />
<br />
'''Omit, Phase''' - A command causing ommission of a phase.<br />
<br />
'''Optically Limited Signal Head''' - A signal head designed to limit the view of a signal indication by internal optical masking. <br />
<br />
'''Orientation''' - Signalization at first turn on or recovery after lengthy power failures of an intersection control.<br />
<br />
'''Output File''' - An assembly in a Type 170 controller cabinet that serves to control high voltage power to signal lamps. The output file contains load switches, transfer relays and the conflict monitor. <br />
<br />
'''Outside Party''' - Organization, entity, agency, etc. other than the Commission or MoDOT. <br />
<br />
'''Overlap''' - A right-of-way indication that allows traffic movement when the right-of-way is being assigned to two or more traffic phases. <br />
<br />
'''Parameter''' - A definable characteristic of an item, device, or system. <br />
<br />
'''Passage Detection''' - The ability of a vehicle detector to detect the passage of a vehicle moving through the detection zone and to ignore the presence of a vehicle stopped within the detection zone. <br />
<br />
'''Passage Time''' - Amount of time it takes a car to leave the loop and get into the intersection. <br />
<br />
'''Peak Hour''' - Hour during a day with highest volume. <br />
<br />
'''Pedestrian Clearance Interval''' - The first clearance interval following the pedestrian WALK indication, i.e. flashing DON'T WALK. <br />
<br />
'''Pedestrian Detector''' - A detector capable of sensing manual operation by a pedestrian. <br />
<br />
'''Pedestrian Indications''' - Signal displays that control pedestrian movement. <br />
<br />
'''Pedestrian Permissive Period''' - Provides an independent permissive period for ped timing, usually requiring more guaranteed time than the vehicle. <br />
<br />
'''Pedestrian Phase''' - A traffic phase allocated to pedestrian traffic that may provide a right-of-way pedestrian indication either concurrently with one or more vehicular phases, or to the exclusion of all vehicular phases. <br />
<br />
'''Pedestrian Recall''' - With the control activation, pedestrian walk and clearance intervals for the phase are timed once during each cycle without the necessity of a push-button actuation. <br />
<br />
'''Percentage''' - Used in lieu of expressing time in seconds since many intervals are a portion of the total cycle. The total cycle length can be changed due to coordination. 100 percent is used to indicate the total cycle length and the splits and intervals are a percentage of that total. <br />
<br />
'''Percentile Speed''' - Information obtained from intersection warrants relating to vehicle speeds in an approach. Example: 80th percentile speed is the speed above which 20% and below which 80% of the speeds occurred in the approach. <br />
<br />
'''Permissive Period''' - Relates to selected periods during coordinated operation in which a call from the opposing phase can be acknowledged. <br />
<br />
'''Permit''' - Agreement between MoDOT and an outside party that modifies the roadway at part or all of the outside party's expense. <br />
<br />
'''Permitted Turn''' - Turning movement where the driver must yield to opposing traffic before completing the movement. <br />
<br />
'''Phase''' - The part of the signal cycle allocated to any combination of traffic movements receiving the right-of-way simultaneously during one or more intervals. Symbol used: 0. <br />
<br />
'''Phase Diagram''' - Illustrates the sequence of phases at an intersection, with movement arrows indicating each phase and showing overlaps, concurrent timing, etc.<br />
<br />
'''Phase-Associated Pedestrian Indications''' - Indications that display WALK and DON'T WALK messages during the green and yellow signal indications for that direction. <br />
<br />
'''Platoon''' - A group of vehicles or pedestrians traveling together as a group, either voluntarily or involuntarily due to signal control, geometrics or other factors. <br />
<br />
'''Posted Speed''' - Speed designated by regulatory signing. <br />
<br />
'''Power Distribution Assembly (PDA)''' - A unit installed in a Type 170 controller cabinet that distributes power, provides circuit protection and surge protection for cabinet equipment. <br />
<br />
'''Preemption''' - The term used when the normal signal sequence at an intersection is interrupted and/or altered in deference to a special situation such as the passage of a train, bridge opening, or the granting of the right of way to an emergency vehicle. <br />
<br />
'''Presence Detection''' - The ability of a vehicle detector to sense that a vehicle, whether moving or stopped, has appeared in its field. <br />
<br />
'''Pressure Sensitive Detector''' - Detector capable of sensing the pressure exerted by a vehicle passing over the surface of its sensor.<br />
<br />
'''Pre-timed Control''' - Traffic signal control in which the cycle length, phase plan, and phase times are preset, and are repeated continuously according to the preset timing plan. <br />
<br />
'''Printed Circuits''' - Circuitry constructed on a special insulation material by the formation of a copper conductor directly onto the material in lieu of using a wire to interconnect to points.<br />
<br />
'''Projected Values''' - Anticipated traffic volumes based on historic data from similar locations. <br />
<br />
'''PROM''' - Program Read-Only Memory. Device that stores data that cannot be altered by computer instructions. <br />
<br />
'''Progression''' - Coordination method based upon offsets between intersections along an artery. Determined by time required to travel from one controlled intersection to the next and adjusted to give artery right of way without delay. <br />
<br />
'''Protected Turn''' - Turning movement that is indicated on the signal faces with a green arrow in the desired direction of travel. <br />
<br />
'''Protected-Permissive Turn Movement''' - A movement that is protected during part of the signal cycle and permitted during another part of the signal cycle. <br />
<br />
'''Pull Box''' - In-ground box which houses cable runs connected by conduit and is accessed by removing a heavy cover plate that protects the contents from damage. Splice between lead-in cable and loop lead-in wire are located here. <br />
<br />
'''Pulse Detection''' - Detection type that produces a short output pulse upon detection, even if the vehicle remains in the detection zone. <br />
<br />
'''Push Button Detector''' - A push button device used to place a call into the signal controller. Typically used with actuated pedestrian indications. <br />
<br />
'''Quadrapole''' - A detector loop configuration that adds a longitudinal sawcut along the center of the rectangle, so that the wire can be installed in a figure-8 pattern thereby producing four electromagnetic poles instead of the normal two. The design improves the sensitivity to small vehicles and also minimizes calls from adjacent or nearby loops. <br />
<br />
'''Queue''' - A line of vehicles or persons waiting to be served by a system. <br />
<br />
'''Radar Detector''' - A detector that is capable of sensing the passage of a vehicle through its field of emitted microwave energy. <br />
<br />
'''Ramp Metering''' - A traffic signal installation placed on a freeway on ramp used to control the rate of flow of traffic entering the freeway traffic stream. <br />
<br />
'''Ramp Terminal''' - The end of a ramp that intersects with a grade separated crossroad. <br />
<br />
'''Random Access Memory (RAM)''' - A storage device with both read and write capabilities allowing random access to stored data. <br />
<br />
'''Rated Initial Lumens''' - The average amount of luminous flux (light) produced by a statistically acceptable sample of lamps on operation at rated voltage after having been seasoned by one half to one percent of rated life <br />
<br />
'''Read-Only Memory (ROM)''' - A storage device not alterable by computer instructions; e.g., magnetic core storage with a lock-out feature. <br />
<br />
'''Rear-End Crashes''' - Crash involving one vehicle striking the back of the vehicle in front. <br />
<br />
'''Recall''' - An operational mode for an actuated controller whereby a phase, either vehicle or pedestrian, is displayed each cycle whether demand exists for it or not. Usually in a temporary or emergency situation. See MIN Recall, MAX Recall, PED Recall, Soft Recall and Extendable Recall. <br />
<br />
'''Red Clearance Interval''' - A clearance interval that may follow the yellow change interval, during which both the terminating phase and the next right of way phase display red. <br />
<br />
'''Red Rest''' - A feature whereby, in the absence of demand, the controller will return to all red instead of resting in green of the last serviced phase. <br />
<br />
'''Remote Flash''' - An input, when energized, causing normal signal operation to be discontinued and specified signal light to be operated in a flashing manner. <br />
<br />
'''Rest''' - The interval portion of a phase when present timing requirements have been completed. <br />
<br />
'''Revision marking''' - Using specific type styles to indicate proposed additions and deletions to a document. <br />
<br />
'''Right Angle Crash''' - Collision/crash where a vehicle traveling in one direction collides with a vehicle approaching from the left or right. <br />
<br />
'''Right of Way (ROW)-''' (1) Period of time where it is lawful for a vehicle to proceed. (2) MoDOT-owned property associated with roadway. <br />
<br />
'''Ring''' - Two or more sequentially timed and individually selected conflicting phases so arranged as to occur in an established order. <br />
<br />
'''ROW & Construction Program''' - Long-term list of highway projects proposed by MoDOT. <br />
<br />
'''RTOR''' - Right Turn On Red. Where right turns are permitted on a steady red indication after a stop. <br />
<br />
'''Saturation Flow Rate''' - The maximum rate of flow that can pass through a given lane group under prevailing traffic and roadway conditions, assuming that the lane group has 100 percent of real time available as effective green time. <br />
Serial Communications - Transmission of digital data over a single line in a sequential fashion. <br />
<br />
'''Secondary Controller Operation (slave)''' - A method of operating the traffic signals under the supervision of a master controller. <br />
<br />
'''Semi-Actuated''' - Identifies type of intersection control with one or more phase lacking vehicle detector input capability. <br />
<br />
'''Sensor''' - The device(s) located in a roadway that is acted upon directly by a vehicle to create a usable pulse to an intersection control. <br />
<br />
'''Sequence''' - The order that signal intervals are displayed around an intersection on a PRE-TIMED control or with calls all around on an actuated control. <br />
<br />
'''Shared Lane''' - A lane at an intersection that is shared by two or three movements. <br />
<br />
'''Sideswipes''' - Crashes where vehicles traveling in the same or opposite direction collide on the sides or side of vehicles. <br />
<br />
'''Sight Distance''' - Distance of a driver's first perception of an object or feature. <br />
<br />
'''Signal Face''' - A section or combination of sections, each capable of displaying its indication in one directions. <br />
<br />
'''Signal Head''' - An assembly containing one or more signal faces. <br />
<br />
'''Signal Indication''' - The illumination of a signal lens (or an equivalent device) whereby the movement of vehicular or pedestrian traffic is controlled. <br />
<br />
'''Signal Installation''' - The traffic signal equipment, signal heads, supports, and electrical circuitry necessary to control vehicle and/or pedestrian traffic at an intersection. <br />
<br />
'''Signal Load Switch''' - A device used to switch power to the signal lamps. <br />
<br />
'''Signal Mast Arm''' - A structural support over the roadway, extending from a pole, for the purpose of supporting the signal head(s). <br />
<br />
'''Signal Pedestal''' - A vertical support on top of which the signal head or controller assembly is mounted. <br />
<br />
'''Signal Plan''' - The set of parameters that define the sequence, timing, and other operational aspects of signal control. <br />
<br />
'''Signal Progression''' - See Coordination. <br />
<br />
'''Signal Section''' - The optical unit and housing capable of displaying one indication. <br />
<br />
'''Signal Sequence''' - The order of appearance of signal indications during successive intervals of a cycle. <br />
<br />
'''Signals''' - Any power-operated traffic control device, other than a barricade warning light or steady burning electric lamp, by which traffic is warned or directed to take some specific action. <br />
<br />
'''Signals, Permanent''' - Signal installation constructed using steel poles and mast arms with underground wiring. <br />
<br />
'''Signals, Temporary''' - Signal installation constructed using poles with signal heads hung from span wires and external wiring. <br />
<br />
'''Skip Phase''' - A feature of actuated intersection controls that omits signalization in a phase or movement that does not have any vehicle or pedestrian calls. Reduces delay by progressing through sequence without timing inactive movements. <br />
<br />
'''Soft Recall''' - Recall option that allows the recalled phase to be skipped provided there is no demand on the recalled phase and a conflicting call to another phase is detected by the controller. <br />
<br />
'''Soft Flash''' - Flash plan where the flashing indications are programmed in the controller instead of wired in the cabinet. <br />
<br />
'''Solid-State Device''' - A device that is characterized by electrical circuits, the active components of which are semi-conductors, to the exclusion of electromechanical devices or tubes. <br />
<br />
'''Span Wire''' - One or more cables used as a means of support for traffic control devices. <br />
<br />
'''Special Event''' - Event occurring outside of normal operating hours that produces traffic. <br />
<br />
'''Split''' - A division of the cycle length allocated to each of the various phases (expressed in seconds or percent). <br />
<br />
'''Split Phasing''' - Serving an intersection one approach at a time. <br />
<br />
'''State Highway System''' - All roadways owned and operated by MoDOT. <br />
<br />
'''Steady Signal Indication''' - Indication that is constantly illuminated, generally for 3 or more seconds. <br />
<br />
'''Stop Bar''' - Thick white line that designates the appropriate stopped location for the first <br />
<br />
'''Stop Time''' - A feature in many intersection controls permitting the application of an external signal to stop any one or all interval timers from timing further. <br />
<br />
'''Storage''' - Ability of a lane to keep waiting vehicles out of the way of moving traffic, expressed in either feet or number of vehicles. <br />
<br />
'''Storage Area''' - The area, usually expressed in terms of the number of vehicles, between the stop line and the detector located upstream. In pre-timed control it may be the number of vehicles arbitrarily used to determine green time. <br />
<br />
'''Synchronization''' - (1) Motors or cam switches designed to remain in step or in the correct rotational relationship at all times. (2) Internal circuitry used to be sure several circuits begin actions from the same reference point. <br />
<br />
'''System Reference''' - An output or signal during coordinated operation that starts the offset timer. <br />
<br />
'''System, Signal''' - Network of two or more signals in coordination. <br />
<br />
'''System Status''' - The operational condition of each monitored remote control unit or data sensing station in the system as indicated bya display or a print-out.<br />
<br />
'''TBC''' - Time Based Coordination. Coordination where controllers in a system are synchronized by a clock and not a master controller. <br />
<br />
'''TBR''' - Time Before Reduction. Time period that begins when the phase is green and there is a serviceable conflicting call. After this period expires, the TTR begins to time down. <br />
<br />
'''Tee Intersection''' - An intersection with three approaches in which one approach meets the other two at approximately right angles. <br />
<br />
'''Telemetry''' - A specific level or value of a parameter above or below a change of activity will occur. <br />
<br />
'''Terminate''' - Applies most frequently in traffic control to the end of a timing interval. Termination of right of way begins in an active phase when a call is received from an inactive phase in a full-actuated control; right of way termination must always include adequate clearance intervals. <br />
<br />
'''Tether Cable''' - Cable used to stabilize overhead signal heads in a span-wire <br />
installation. <br />
<br />
'''Threshold''' - A specific level or value of a parameter that above or below a change of activity will occur. <br />
<br />
'''Through Movement''' - A movement at an intersection that continues in a straight line and across the intersection; does not turn in any direction. <br />
<br />
'''Time Base Coordination''' - Coordinated operation in response to internally generated time clock commands selecting cycle, split and offset. <br />
<br />
'''Time Clock''' - A device for the automatic selection of modes of operation of traffic signals in a manner prescribed by a predetermined time schedule. <br />
<br />
'''Time Out''' - The state of an interval timer that was timed for the preset period and has produced a signal so indicating. At time out, the timing device ceases to be in control since another action is initiated by the timing out of the timer. <br />
<br />
'''Time/Space Diagram''' - A semi-pictorial presentation of two or more intersections being coordinated that shows the offset, cycle and distance relationships. <br />
<br />
'''Time Waiting''' - Related to cars waiting in volume-density control methods, but represents the time vehicles must wait in an opposing phase before termination of the phase having right of way begins. Imposing restrictive action upon the phase having the right of way to decrease delay in opposing phases. <br />
<br />
'''Timing''' - Values, usually in seconds, which give lengths of signal indications and other functions. <br />
<br />
'''Tone Interconnection''' - Inefficient interconnection method that transmits timing plans and offset breaks. <br />
<br />
'''Traffic Actuated''' - A type of traffic control signal where the intervals are varied according to the demands of traffic as registered by detector actuation. <br />
<br />
'''Traffic Adjusted''' - Term used in master supervisory systems where vehicle actuations and other data are fed to the master for effecting signalization changes at several intersections rather than at each intersection independently. <br />
<br />
'''Traffic Count''' - Summary of traffic volumes by approach and/or time period. <br />
<br />
'''Transfer Relay''' - Relay used to transfer control between normal signal operation and flashing operation. When the relay is energized, the signal operates off the load switches and when the relay is de-energized, the signal operates in a flash mode. <br />
<br />
'''Traffic Responsive System''' - A system where a master controller specifies cycle/split/offset on the real-time demands of traffic as sensed by vehicle detectors. <br />
<br />
'''Trailing Green''' - Usually an overlap phase coupled with a through phase that permits a turn movement to continue a fixed interval after the through movement has been stopped. <br />
<br />
'''TRB''' - Transportation Research Board. Research organization sponsored by AASHTO and the Federal Highway Administration. <br />
<br />
'''TTR''' - Time To Reduce. Time period by which the measured gap between vehicles is reduced from the passage time to a value equal to the minimum gap. A measured gap greater than the instantaneous calculated gap shall cause the phase to be terminated due to gap out. <br />
<br />
'''Turning Radius''' - Designed radius that allows for the turning of a certain type of vehicle through an intersection. <br />
<br />
'''Two-Way Stop''' - Two approaches at an intersection controlled by a STOP sign, with the major movements allowed to continue through. <br />
<br />
'''Type 170''' - Alternate signal controller design that stresses interchangeability and simplified maintenance by building all components to the same hardware specification. <br />
<br />
'''Ultrasonic Detector''' - Ultrasonic detectors use the same principle as the microwave detectors: a transducer transmits a beam of energy into an area and receives a reflected beam from a vehicle. The sonic detector transmits pulses of ultrasonic energy (20 to 50 kHz at 20 to 25 times/sec) through a transducer. The passage of a vehicle causes a beam to be reflected to the transducer at a different frequency. The transducer senses the change in frequency and converts it to electrical energy. This energy is relayed to a transceiver, that then sends an impulse to the controller unit to denote passage of a vehicle. <br />
<br />
'''Upstream''' - The direction from which traffic is flowing. Vehicles are to obey the red indication or STOP message. <br />
<br />
'''Visor''' - The part of a signal section that protects the lens face from direct ambient light. <br />
<br />
'''Voice Grade Lines''' - A channel suitable for transmission of speech, digital, analog or facsimile data, generally in the frequency range of 300 to 3000 Hz.<br />
<br />
'''Volume''' - The number of persons or vehicles passing a point on a lane, roadway, or other trafficway during some time interval, often taken to be 1 hour, expressed in vehicles or persons. <br />
[[image:902.12 Truck.jpg|right|150px]]<br />
'''Volume Classification''' - Summary of vehicle types (i.e. trucks, buses, cars) by percentage of volume. <br />
<br />
'''Volume Density''' - A process used with detectors located at, or at sufficient distance in advance of, the intersection that makes use of vehicle actuation quantities and time-of-waiting of the vehicles to vary green interval portions for increased capacity and minimized delays. <br />
<br />
'''VPH-''' Vehicles Per Hour, the total number of vehicles passing a given point per hour. <br />
<br />
'''Warrants''' - Criteria used to determine the need for traffic signals or other traffic control devices that presents quantitative procedures to solving many traffic engineering problems. <br />
<br />
'''Yellow Change Interval''' - The first interval following the green right-of-way interval in which the signal indication for that phase is yellow. <br />
<br />
'''Yielding Movement''' -Turn movement that is required to yield to conflicting movements that have higher priority.<br />
<br />
'''Zone of Detection''' - (Area of Detection, Effective Loop Area, Field of Influence, Sensing Zone) The area of the roadway within which a vehicle is to be detected by a vehicle detector system. <br />
<br />
<br />
[[Category:902 Signals]]</div>Jonesjbhttps://epg.modot.org/index.php?title=231.2_Clear_Zones&diff=27046231.2 Clear Zones2012-01-09T16:08:05Z<p>Jonesjb: /* 231.2.1 Introduction */ Clarified the difference between a deliberate 'Clear Zone' and an incidental 'Clear Area.'</p>
<hr />
<div>[[image:231.2 Clear Zone.jpg|left|400px]]<br />
<br />
===231.2.1 Introduction===<br />
<br />
The [[media:231.2 Examples of a Parallel Foreslope Design.pdf|clear zone]] is an unobstructed, traversable area provided beyond the edge of the through traveled way for the recovery of errant vehicles. The provision of a clear zone is only applicable to new construction and re-construction projects pursuant to guidance outlined in the Roadside Design Guide. On existing roads, primarily those of an older or lower-order nature, a clear area has been established through maintenance activities. While this practice is strongly encouraged, these areas should not be construed as providing the same safety benefit as clear zones.<br />
<br />
In general, the clear zone, or forgiving roadside concept is the preferred method of achieving roadside safety. The four methods of establishing a clear zone are listed here in order of preference:<br />
<br />
:1) Eliminate obstacles.<br />
:2) Redesign obstacles so they can be safely traversed.<br />
:3) Relocate obstacles to a location where they're less likely to be struck.<br />
:4) Reduce the impact severity of obstacles by using appropriate breakaway devices.<br />
{|style="padding: 0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right"<br />
|-<br />
|'''Figures'''<br />
|-<br />
|[[:Category:231 Typical Section Elements for Roadways|Roadway Typical Sections]]<br />
|-<br />
|[[media:231.2 Clear Zone Distance Curves.pdf|RDG Figure 3.1 "Clear-Zone Distance curves"]]<br />
|-<br />
|[[media:231.2 Horizontal Curve Adjustments.pdf|RDG Table 3.2 "Horizontal Curve Adjustments"]]<br />
|-<br />
|[[media:231.2 Examples of a Parallel Foreslope Design.pdf|RDG Figure 3.2 "Example of a Parallel Foreslope Design"]]<br />
|-<br />
|[[media:231.2 Preferred Cross Sections for Channels with abrupt slope changes.pdf|RDG Figure 3.6 "Preferred Cross Sections for Channels with Abrupt Slope Changes"]]<br />
|}<br />
Clear zone widths are most affected by the traffic’s speed and volume and the slope of the area adjacent to the travelway. Appropriate clear zones are selected for projects using [[media:231.2 Clear Zone Distance Curves.pdf|Figure 3.1]] from the RDG after consulting the [[:Category:126 Location Study and Alternatives Analysis|location study report]].<br />
<br />
Clear zones are provided where the anticipated posted speed of the roadway is 45 mph or more. When the anticipated posted speed is less than 45 mph, clear zones are still beneficial but they are to be considered only if economically feasible. Non-traversable slopes or fixed objects are to be removed, relocated or shielded by a barrier if they are within the indicated minimum clear zone width and it is cost effective to do so. Higher speeds result in vehicles traveling farther off the travelway before control is recovered. Horizontal curvature increases the likelihood of a vehicle leaving the travelway and increases the distance it travels. The designer may choose to modify the clear zone distance obtained from RDG Figure 3.1 by using [[media:231.2 Horizontal Curve Adjustments.pdf|Table 3.2]] (adjusting the values for horizontal curvature as necessary). These modifications are normally only considered where accident histories indicate a need, or a specific site investigation shows a definite accident potential which could be significantly lessened by increasing the clear zone width and such increases are cost-effective. Steeper slopes adjacent to the travelway increases the distance the vehicle travels beyond the travelway. In the implementation of the clear zone concept it is important for clear zone distances to not be used as boundaries for introducing roadside hazards such as bridge piers or trees. These are to be as far from the travelway as practical.<br />
<br />
[[image:231.2.1 Cut Section.jpg|right|175px|thumb|<center>'''Cut Section'''</center>]]<br />
The clear zone width is to be applied with good judgment. If an obstacle lies just beyond the clear zone, it is to be removed or shielded if costs are reasonable. Conversely, the clear zone is not to be obtained at all costs. Limited right of way or high construction costs may lead to the installation of a barrier or possibly no protection at all. <br />
<br />
As may be noted, roadside slopes apply an important part in the clear zone width determination. Fill slopes of 1V:6H/1V:3H are preferred in areas of high fill, that is, a 1V:6H slope extending from the shoulder line out for a distance necessary to obtain the clear zone then break the slope to 1V:3H or flatter. If feasible, the flattening of slopes is preferable to installation of guardrail. In cut sections, the roadside ditch is likely to be located within the clear zone. Therefore, the configuration of the ditch and the type of [[:Category:806 Pollution, Erosion and Sediment Control|erosion control treatment]] used in the ditch must be viewed with respect to clear zone requirements. Namely, side slopes of the ditch and the method of erosion control used in the ditch must be traversable by vehicles that leave the roadway. [[media:231.2 Preferred Cross Sections for Channels with abrupt slope changes.pdf|Figure 3.6]] in the RDG is to be checked for preferred ditch cross-sections. Ditch sections must be within the shaded portions of the guides for use with clear zones. Background for this procedure is contained in Appendix A of the RDG. Any deviation from the preferred slope will be considered a special condition and is to be justified by costs or other considerations.<br />
<br />
===231.2.2 Clear Zone Perception Issues===<br />
<br />
In most cases, the use of the clear zone concept is preferable to the use of a shielding barrier. There is, however, a notable exception.<br />
<br />
Occasionally the public will poorly perceive the clear zone concept. In areas of very high fills, particularly those on the outside of a horizontal curve, the clear zone alone may give the impression of an unsafe situation. Even though the design may be completely safe within the guidance of the RDG the public will inevitably request the area be shielded, most often with guardrail. <br />
<br />
In these cases, the best practice is to initially specify shielding. By doing so, MoDOT can avoid the needless expense of eventually using both treatments in the same location.<br />
<br />
===231.2.3 For Bridges and Culverts===<br />
<br />
Clear zones, when used, shall extend full-width to bridge ends. Where the existing roadway is to be incorporated into the completed facility as part of the main roadway, the use of clear zones will be considered on individual projects.<br />
<br />
The use of [[:Category:231 Typical Section Elements for Roadways|clear zone typical sections]] is not applicable to small culvert replacement projects where the intent is to continue the service of the road without upgrading it. In such cases, the typical sections used in the original construction are to be used except that the roadbed width is not to be more narrow than 24 ft.<br />
<br />
In shallow fills and in cuts where box or pipe culvert normally require a headwall to be located in the clear zone, the structure should be extended to place the headwall at the outside of the clear zone or a safety appurtenance (guardrail or barrier) should be provided. The slope of the clear zone will then require modification over the entire surface.<br />
<br />
===231.2.4 On Ramps===<br />
<br />
Flattened slopes or clear zones are to be used on ramps to eliminate the use of guardrail. Use guardrail only to protect bridge ends within the interchange area.<br />
<br />
===231.2.5 In Unusual Conditions===<br />
<br />
When a standard clear zone width and slope will not properly terminate on the existing ground surface because of hilly conditions, steeper slopes must be used. In this case, the clear zone may be omitted and guardrail used at the shoulder line. The desirable minimum length for the elimination of clear zone is 500 ft. but in no case less than 250 ft. <br />
<br />
For long fill sections through a reservoir project, clear zones can be eliminated and guardrail used at the shoulder lines.<br />
<br />
Speed change lanes adjacent to main roadway are to be placed within main roadway's clear zone with no widening of clear zone. The clear zone is always located adjacent to and measured from the normal edge of the pavement of the main roadway including climbing or continuous auxiliary lanes.<br />
<br />
===231.2.6 Maintenance===<br />
<br />
District personnel shall be responsible for maintaining clear zones on highway improvement projects.<br />
<br />
[[category:231 Typical Section Elements for Roadways|231.02]]</div>Jonesjbhttps://epg.modot.org/index.php?title=Category:123_Federal-Aid_Highway_Program&diff=27029Category:123 Federal-Aid Highway Program2012-01-04T15:47:31Z<p>Jonesjb: /* 123.1.1 FHWA Oversight - National Highway System */ Clarified oversight parameters.</p>
<hr />
<div>{| style="padding:0.3em; margin-left:15px; border:1px solid #a9a9a9; text-align:center; font-size: 95%; background:#f5f5f5" width="160px" align="right"<br />
|-<br />
|'''Additional Information'''<br />
|-<br />
|[[:Category:136 Local Public Agency (LPA) Policy|Local Public Agency (LPA) Policy]]<br />
|-<br />
|[[Independent Assurance Samples and Tests|Independent Assurance Samples and Tests (IAS)]] <br />
|-<br />
|[[Federal-Aid Acceptance Sampling and Testing|Federal-Aid Acceptance Sampling and Testing (FAST)]]<br />
|-<br />
|[[Off-Systems Guide Schedule for Federal-Aid Acceptance Sampling and Testing (FAST)|Off-Systems Guide Schedule for Federal-Aid Acceptance Sampling and Testing (FAST)]]<br />
|}<br />
<br />
<br />
<br />
==123.1 Discussion==<br />
<br />
The Federal Highway Administration (FHWA) is one of the key partners with MoDOT in delivering the highway program in the State of Missouri. Federally controlled funding of highway projects is an essential part of planning, design, construction, and preventive maintenance activities undertaken by MoDOT. The FHWA is one of the agencies under the U.S. Department of Transportation and is responsible for administering the Federal-Aid Highway Program nationwide. In addition to the Washington Headquarters office and Resource Centers, the FHWA has a division office in each state to provide direct assistance and guidance to the individual state highway departments. The primary sources of guidance on the Federal-Aid Program are available in Title 23, United States Code - Highways, 23 Code of Federal Regulations (CFR), the [http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_public_laws&docid=f:publ059.109.pdf current federal highway act,]and the Federal-Aid Policy Guide (FAPG). These documents provide current regulations, policies and procedural guidance.<br />
[[image:123.1 Interstate history.jpg|right|425px|thumb|'''Six involved in one of the nation's first interstate projects pose in St. Charles at the Interstate 70 project site in 1956. From left to right are Dan Cane, superintendent, Cameron, Joyce & Company; Chick Sayles, salesman, Alpha Portland Cement; John Latham, District 6 engineer; Charles Tevis, District 6 assistant chief engineer; and Jack and Tinch Gammon, brothers who owned Cameron, Joyce & Company, the contractor on the project.''']]<br />
To ensure projects qualify for federal funding and obtain the maximum participation, compliance with federal laws, regulations and FHWA policies and procedures is necessary. This is accomplished through a close partnership arrangement with MoDOT and has included innovative methods and practices to enhance program implementation. FHWA and MoDOT have entered into an [[media:123 Stewardship-Oversight Agreement.pdf|oversight agreement]] that allows MoDOT to discharge some responsibilities traditionally performed by FHWA for projects not on the Interstate highway system. This agreement documents the roles and responsibilities of both FHWA and MoDOT in carrying out the Federal-Aid Highway Program. This includes identification of the type of projects that will require full oversight by FHWA, or are exempt from FHWA oversight. All Federal-Aid projects, regardless of whether MoDOT has responsibility for administration, must comply with all applicable federal regulations in order to receive federal-aid funding. Specific guidance and assistance in implementing the Federal-Aid Program is available from the FHWA Missouri Division office in Jefferson City.<br />
<br />
To further reinforce this close partnership, FHWA will be given the opportunity to participate in task forces and other quality improvement teams established to review existing processes and procedures to improve implementation of the MoDOT transportation program.<br />
<br />
===123.1.1 FHWA Oversight - National Highway System===<br />
<br />
The National Highway System (NHS) includes the entire interstate system and other urban and rural [[Image:123.1 Mo NHS Map.GIF|right|thumb|240px|[http://www.fhwa.dot.gov/planning/nhs/maps/mo/mo_Missouri.pdf '''Missouri Routes'''] in the National Highway System]] principal arterials along with major highway network connectors. The FHWA has the responsibility to ensure the safety, appropriate design, and national continuity of the NHS. This is accomplished through the [[media:123 Stewardship-Oversight Agreement.pdf|Stewardship/Oversight Agreement]]. The following briefly describes the oversight role of FHWA:<br />
Full Oversight Projects are individual projects that require approval by FHWA for all project actions. They are:<br />
<br />
* All Interstate projects, including bridges, with an estimated construction cost in the current STIP of greater than or equal to $5 million<br />
<br />
* All NHS projects, including bridges, with an estimated construction cost in the current STIP of greater than or equal to $20 million<br />
<br />
* All bridges with any span length of 500 feet or more or unusual features<br />
* Any project of special interest to FHWA.<br />
<br />
===123.1.2 Federal Appropriations===<br />
<br />
Current legislation provides for the appropriation of federally controlled funds from the Highway Trust Fund for the purposes of carrying out the provisions of Title 23, U.S.C. Funds are divided among the various states by an apportionment process. These funds are subject to mandatory limitations established by the U.S. Congress each fiscal year to help control spending and drawdown of the Highway Trust Fund. A certain percentage of the apportioned funds are directly allocated to urbanized areas with a population over 200,000 and are subject to the control of a metropolitan planning organization (MPO). In Missouri, the urbanized areas over 200,000 in population are St. Louis, Kansas City and Springfield. The cities of St. Joseph, Joplin, Columbia, and the City of Jefferson also have MPO's but do not receive a direct allocation of funds. Other major funding categories are:<br />
<br />
: '''Interstate Maintenance (IM)'''. IM funds can be used for resurfacing, restoration, and rehabilitation, but not for the construction of new travel lanes unless they are high occupancy vehicle (HOV) or auxiliary lanes.<br />
<br />
: '''National Highway System (NHS)'''. NHS funds may be used for a variety of projects on the NHS including construction, reconstruction, resurfacing, restoration, and rehabilitation, operational and safety improvements, start-up costs for traffic management and control systems, fringe and corridor parking facilities, carpool and vanpool projects, and bicycle and pedestrian facilities.<br />
<br />
: '''Surface Transportation Program (STP)'''. These funds may be used for any highways, including the NHS, that are not functionally classified as local or rural minor collectors. Eligible items of work are similar to those under the NHS. However, 10% must be used for transportation enhancements and 62.5% of the remaining funds are sub-allocated to areas of the state based on population.<br />
<br />
: '''Highway Bridge Replacement and Rehabilitation Program (HBRRP)'''. Eligible projects for HBRRP funding include replacement or rehabilitation of a structurally deficient or functionally obsolete highway bridge, replacement of ferryboat operations and low water crossings, bridge painting, calcium magnesium acetate applications, and seismic retrofitting. Additionally, not less than 15% will be spent on off-system bridges.<br />
<br />
===123.1.3 Programming===<br />
<br />
To ensure coordination of intergovernmental planning and before any federal-aid programs are approved by FHWA, all projects must be cleared under the Missouri State and Local Review System. Briefly, this is described as:<br />
<br />
:'''State Clearinghouse''' The State Clearinghouse, after notifying other state agencies, certifies to MoDOT that these agencies have been informed of the project and have indicated whether the proposed work conflicts with their programs.<br />
<br />
:'''Regional and Metropolitan Clearinghouses''' Similar clearance must be received from regional and metropolitan clearinghouses who notify appropriate local governments and other regional agencies in the area. These clearinghouses provide comments to the MoDOT on proposed projects. Any adverse comments received from the clearinghouses must be resolved. In order for any proposed project to be eligible for federal funding, it must be included on the Statewide Transportation Improvement Program (STIP). Before any work is performed for which federal reimbursement is expected, FHWA must provide approval. MoDOT district offices will notify the Design Division as soon as possible if any proposed work is identified that is not on the approved STIP. For projects to be constructed in stages, a separate item will be shown on the STIP for each stage.<br />
<br />
===123.1.4 Federal Authorization===<br />
<br />
Authorization to proceed with a federal-aid project can be given only after applicable requirements of federal laws and regulations have been satisfied, including the planning and programming items noted above. For construction projects, additional requirements must be completed such as an approved environmental document, right-of-way clearance, and submission of a request to FHWA by MoDOT to authorize construction with the obligation of funds. Authorization to proceed is considered a contractual obligation of the Federal Government under 23 U.S.C. 106 and federal funds will not participate in costs incurred prior to the date of authorization.<br />
<br />
==123.2 Construction Inspection Guidelines==<br />
<br />
===123.2.1 General Procedures===<br />
<br />
On Federal-Aid highway projects, the terms of federal participation are established by an [[media:123 Stewardship-Oversight Agreement.pdf|oversight agreement]] between the department and the FHWA. This agreement provides for the work to be done in accordance with predetermined criteria contained in the plans and specifications, in approved standard drawings, and in special provisions required by the nature of the project.<br />
<br />
The Missouri Highway and Transportation Commission will award a construction contract for the project with the concurrence of the FHWA. Supervision of construction is a function of the MoDOT’s engineers and inspectors. FHWA representatives may make periodic inspections of these projects and will complete a final inspection and final acceptance.<br />
<br />
===123.2.2 The FHWA - MoDOT Relationship===<br />
<br />
The relationship between the FHWA and MoDOT does not directly involve the contractor. FHWA representatives inspect the project to review MoDOT’s procedures for assuring the project is built according to commitments contained in project documents, MoDOT/FHWA agreements and to assure that the contractor follows proper construction practices. Any deficiencies noted by the FHWA representative shall be documented and conveyed to MoDOT’s engineer or inspector. MoDOT will work directly with the contractor to resolve these deficiencies.<br />
<br />
MoDOT employees are expected to cooperate with FHWA representatives in their inspections. Note their comments in the diary. Promptly refer to the resident engineer matters that require their attention. Should a FHWA representative give instructions to a MoDOT employee which appears to be in conflict with MoDOT policy, the FHWA representative should be courteously informed that the employee has no authority to carry out such instruction but will refer the matter to the appropriate supervisor.<br />
<br />
The MoDOT inspector, as directed by the [[:category:105 Control of Work#105.9 Authority and Duties of Resident Engineer (Sec 105.9)|resident engineer]], will inform FHWA representatives of necessary extra work and of any proposed changes on [[:Category:123 Federal-Aid Highway Program#123.1.1 FHWA Oversight - National Highway System|full oversight projects]]. All major changes must have concurrence of the FHWA before any of the work is started.<br />
<br />
An [[media:123 Stewardship-Oversight Agreement.pdf|oversight agreement]] signed by MoDOT and FHWA, outlines the specific procedures which the Construction and Materials Division together with the district must follow in the administration of a project. MoDOT will complete a final inspection and final acceptance on projects exempt from FHWA full oversight. The FHWA reserves the right to observe a project under MoDOT responsibility, including those conducted by a [[:Category:136 Local Public Agency (LPA) Policy|Local Public Agency (LPA)]] at any time.<br />
<br />
==123.3 Materials Requirements==<br />
<br />
===123.3.1 Independent Assurance Samples and Tests (IAS) System Based===<br />
<br />
====123.3.1.1 Scope====<br />
To establish procedures for sampling, testing and reporting Independent Assurance Samples (IAS) on all Federal-aid projects. Federal-aid projects are Interstate, Primary and Secondary projects let and administered by MoDOT, and Off-System and Federal-aid Urban projects let and administered by a county, city, or MoDOT.<br />
<br />
====123.3.1.2 General====<br />
These procedures apply to all projects, with an emphasis on Federal-aid projects. These procedures do not change normal job control procedures for any projects. <br />
<br />
The intent of the IAS process is to confirm that inspectors are knowledgeable in the specification governing the testing procedures and follow through with completing the tests correctly, and have equipment that is in good working condition and is properly calibrated, where applicable. This IAS process is considered system based and the audit of a given inspector does not have to take place on a Federal-aid project. The inspector should use the same diligence and attention to detail at all times, regardless whether the project has Federal-aid status. Inspectors on Off-System projects will be audited on the specific project, in most instances. (See [[:Category:123 Federal-Aid Highway Program#123.3.2 Independent Assurance Samples and Tests (IAS) Project Based Based|EPG 123.3.2]].)<br />
<br />
The individual performing the IAS audit on an inspector is herein referred to as the IAS Auditor. Any person can be assigned the duties of the IAS Auditor however each district must designate an individual or individuals who aggregately have Technician Certification in all areas covered by the IAS program. The individual(s) must have been reviewed and compared favorably to another Central Office auditor within the last calendar year, and should have significant experience in materials inspection.<br />
<br />
System Based IAS will not be limited to tests traditionally performed on certain materials, but will be extended to all tests of all materials. The process will include all project and non-project inspection. A prioritization process, described below, will be used to allocate resources so those inspectors responsible for Federal-aid projects are audited first. When resources allow, other inspectors will be audited using the procedures described here.<br />
<br />
====123.3.1.3 General Procedures====<br />
<br />
=====123.3.1.3.1 Report Review=====<br />
As an aid in the prioritization and completion of audits, the following reports, that are available in Cognos 8: Public Folders/SM Reporting/Headquarters/IAS Process Reports, may be used. <br />
<br />
'''IAS Auditors.''' This report lists the individuals from Central Office and the districts who have been designated as an IAS Auditor. Central Office maintains this list (by placing a “y” in Generic Indicator 3 of SM’s Material User window). The District Construction and Materials Engineer designates district auditors. The State Construction and Materials Engineer designates Central Office auditors. An auditor may only audit inspectors in the Technician Certification areas where his/her credentials are current. <br />
<br />
'''SiteManager User Review.''' This report lists SM users. Every person who inspects a project, a material, or has responsibility for related data should be in the list. The IAS Auditor will review the report at least quarterly and submit any necessary changes to Central Office. The following checks should be made:<br />
<br />
:All the individuals who need to be in the list for a district are listed.<br />
:The District column should match the M.U. District.<br />
:The User ID should match the User ID assigned by Information Systems. Typically this will be correct. If you discover otherwise, please advise HQ immediately.<br />
:The User Name may or may not contain “assigned” initials. Either is acceptable.<br />
:User Title should be correct. Abbreviations are acceptable.<br />
:UN Authority indicates the ability to unauthorize a sample record. “YES” means the user may unauthorize his/her own samples. “ALL” means the user can unauthorize any sample record. If the status of the individual changes such that this setting is no longer valid, notify Central Office.<br />
:Last Use SM indicates the date that the user last logged into SM. If the date is blank, the user has not logged on since the function was added to SM. A column indicates “Inactive” if the date is missing, or the date is more than one year old. If the user is indicated as Inactive, consider whether the user even needs access to SM. If not, notify Central Office and provide the justification for removing the person from the system.<br />
<br />
'''Inspector Run Target Tests.''' This report lists inspectors who have run one or more of the IAS specific tests in the target time period. Only the most recent instance of a given test is listed. Note that not all inspectors will be listed in this report. If an inspector has not run any of the target tests and is not shown by this report, the inspector may show in one or more of the other reports.<br />
<br />
'''Active Project Federal Aid.''' This report lists inspectors who have made Daily Work Reports in SM, which implies the acceptance of material. Note that not all users will be listed in this report. If an inspector has not completed a Daily Work Report in the target time frame, the inspector will not be listed. The purpose of this report is to identify inspectors who are accepting material on Federal-aid projects but who are not otherwise audited by the IAS process. If previous reports listed inspectors but did not trigger an audit of the inspector, then this report is used to confirm that the inspector has no interaction with Federal-aid projects. The inspector can still be audited, and should be if time and resources allow.<br />
<br />
:The inspector will be listed by User ID<br />
:The report may not return the desired inspector. This means the inspector has no activity within the criteria of this report.<br />
:The Contract ID may repeat in several columns. This is normal.<br />
:The Daily Work Report Create Date shows the most recent entry for the contract shown. It is used to validate whether the data is recent enough to be considered.<br />
<br />
'''Assigned Equipment.''' This report lists the equipment that has been indicated as assigned to the specific inspector or work group, or district. The report is used as a starting point during the audit of an inspector. If the inspector’s equipment is listed, then the data can be reviewed. If the equipment is not listed, the necessary data must be collected and entered into SM. See [[:Category:123 Federal-Aid Highway Program#123.3.1.4.9 Equipment Review|EPG 123.3.1.4.9]].<br />
<br />
=====123.3.1.3.2 Audit Procedure=====<br />
An IAS Audit should be performed on each inspector who meets the following criteria based on the previous calendar year plus the year to date. (For example, if today were May 8, 2010, look at the year starting January 1, 2009 through May 8, 2010.) Listed below are the audit criterion and instructions for the actions to be taken under various circumstances.<br />
<br />
The inspector was assigned to do, or did inspection of material on any project, or created documentation related to inspection. (Note that “inspection” includes allowing the material to be incorporated into the project.) If not, no further action is taken with this inspector at this time.<br />
<br />
At least one project the inspector inspected was a Federal-aid project. If not and when audit resources are severely limited, this inspector will be reconsidered after all Federal-aid inspectors have been audited.<br />
<br />
======<center>'''Table 123.3.1.3.2'''</center>======<br />
{| border="1" class="wikitable" style="margin: 1em auto 1em auto"<br />
|+ ''The individual performed one or more tests fitting the following designations"''<br />
! style="background:#BEBEBE"|Test Designation !! style="background:#BEBEBE"|General Description of Test !! style="background:#BEBEBE"|Material Source <br />
|-<br />
|[[106.3.2.71 TM-71, Deleterious Content of Aggregate|MoDOT TM-71]]|| Deleterious|| Aggregate<br />
|-<br />
|SAA001LA|| Deleterious || Aggregate<br />
|-<br />
|SAA002AC|| Gradation Aggregate|| Concrete<br />
|-<br />
|SAA002EC|| Gradation/PI|| Aggregate Base<br />
|-<br />
|SAA002GA|| Gradation || Aggregate Base<br />
|-<br />
|SAA002HA|| Gradation || Aggregate Base<br />
|-<br />
|SAA002IF|| Gradation/Deleterious Aggregate||Asphalt<br />
|-<br />
|SAA002JE|| Gradation/Deleterious Aggregate||Concrete<br />
|-<br />
|SAA002JF|| Gradation/Deleterious Aggregate ||Concrete<br />
|-<br />
|SAA002LD|| Gradation/Deleterious Aggregate||Concrete<br />
|-<br />
|SAA002MB|| Gradation Aggregate|| Concrete<br />
|-<br />
|SAA002UB|| Gradation/Deleterious/PI|| Aggregate Base<br />
|-<br />
|SAA002VB|| Gradation|| Aggregate Surfacing<br />
|-<br />
|SAA002WA|| Gradation/PI|| Base/Soil<br />
|-<br />
|SAA003AA|| Density – Nuclear|| Soil<br />
|-<br />
|SAA003CA|| Density|| Asphalt<br />
|-<br />
|SAA003DA|| Density – Nuclear|| Aggregate Base<br />
|-<br />
|SAA003ED|| Binder Content – Nuclear/Ignition|| Asphalt<br />
|-<br />
|SAA003GA|| Density ||Subgrade<br />
|-<br />
|SAA007EB|| Gradation/PI/Deleterious/Density|| Aggregate Base<br />
|-<br />
|SAA024AB|| Binder Content–Nuclear/Ignition ||Asphalt (Superpave)<br />
|-<br />
|SAA400AB|| Gradation/Binder Content/Density|| Asphalt<br />
|-<br />
|SAA502AA|| Thickness/Compressive Strength|| Concrete<br />
|-<br />
|SAA502BA|| Entrained Air Content/Slump|| Concrete<br />
|-<br />
|SAA550AB|| Entrained Air Content/Slump|| Concrete<br />
|-<br />
|SAA551AB|| Thickness/Compressive Strength|| Concrete<br />
|-<br />
|SAA553AE|| Gradation/Deleterious|| Aggregate<br />
|-<br />
|SAA599AB|| Compressive Strength|| Concrete<br />
|-<br />
|SAE005CA|| Entrained Air Content/Slump|| Concrete<br />
|-<br />
|SAM005CA|| Entrained Air Content/Slump|| Concrete<br />
|-<br />
|SLA037CB|| Gradation|| Aggregate<br />
|-<br />
|T11|| Gradation|| Aggregate<br />
|-<br />
|T22|| Compressive Strength|| Concrete<br />
|-<br />
|T27|| Gradation|| Aggregate<br />
|}<br />
<br />
If the inspector did not perform any of the tests listed above, skip to [[:Category:123 Federal-Aid Highway Program#123.3.1.3.2.3|EPG 123.3.1.3.2.3]] and continue the review of this inspector.<br />
<br />
======123.3.1.3.2.1======<br />
If the inspector ran one or more of these tests on a project but did NOT have the appropriate Technician Certifications to run the test(s) or some of the Technician Certifications were expired, notify the appropriate supervisor(s) that the inspector is not to perform testing without the required credentials. Create a record of the audit and indicate the inspector as not comparing favorably.<br />
<br />
======123.3.1.3.2.2======<br />
If the inspector ran one or more of these tests on a project and did have the appropriate Technician Certifications to run the test(s) and the Technician Certification was current at the time of the testing:<br />
:1. Review the inspector's sample records.<br />
:2. Schedule a meeting with the inspector.<br />
:3. Audit the equipment in accordance with [[:Category:123 Federal-Aid Highway Program #123.3.1.4.9 Equipment Review|EPG 123.3.1.4.9]]. If the equipment is not suitable for testing, alternate equipment should be used. Unsuitable equipment should not be used for any testing until repaired, calibrated or otherwise made worthy.<br />
:4. Audit the various tests the inspector is certified to run (Audit means the inspector runs the test while the IAS Auditor observes, and for some tests the IAS Auditor runs companion tests for comparison.).<br />
:5. Discuss the inspector's sample records with the inspector, with focus on clarity, completeness, and compliance of the record with manuals and specifications.<br />
:6. Discuss the test results. This may be done by phone if they compare favorably and the companion results were not yet determined at the time of the audit.<br />
:7. Create a record of the audit and indicate the inspector as comparing or not comparing favorably.<br />
::a. The record will include a list of each test run or observed, and the results for that test.<br />
::b. The supervisor will be notified of the inspector’s audit results, and of any restrictions that exist following the audit, or recommendations that the inspector not be allowed to run certain tests. <br />
::c. The inspector may not be allowed to perform material testing in any deficient area(s) until a follow-up audit finds that the deficiency has been resolved. It will be the inspector’s responsibility to contact Central Office and schedule the follow-up audit. Central Office personnel will perform any follow-up audits.<br />
::d. If a follow-up audit is required, and performed, and the inspector is still deficient on one or more of the designated tests, the applicable Technician Certification will be suspended pending retraining.<br />
::e. If a follow-up audit is required, and performed, and the inspector is still deficient in record keeping or general inspection practice, a recommendation of “not meeting expectations” will be forwarded to the supervisor for MAPS, with copies of the justification forwarded to the District Construction and Materials Engineer and the State Materials Engineer for potential additional action.<br />
<br />
======123.3.1.3.2.3======<br />
If the inspector did not run any of the designated tests but ran other tests or was responsible for the review of material in any other way, such as certification review, visual inspection, or acceptance by PAL, perform the following:<br />
<br />
:1. Review the inspector's sample records<br />
:2. Schedule a meeting with the inspector <br />
:3. Audit the various tests the inspector ran (Audit in this sense means the Auditor will take typical material as might be found on the inspector’s current project, or material brought to the meeting by the Auditor, and have the inspector perform the appropriate inspection.)<br />
:4. Audit the equipment in accordance with [[:Category:123 Federal-Aid Highway Program #123.3.1.4.9 Equipment Review|EPG 123.3.1.4.9]].<br />
:5. Discuss findings in the inspector's sample records with the inspector.<br />
:6. Create a record of the audit in accordance with Automation Section, and indicate the inspector as comparing or not comparing favorably.<br />
::a. The record will include a list of each test run or observed, and the results for that test. (Test means inspection process such as look-up of pre-approved material, or review of certification in accordance with the specification.<br />
::b. The supervisor will be notified of the inspector’s audit results, and of any restrictions that exist following the audit, or recommendations that the inspector not be allowed to run certain tests. <br />
::c. The inspector may not be allowed to perform material testing in any deficient area(s) until a follow-up audit finds that the deficiency has been resolved. It will be the inspector’s responsibility to contact Central Office and schedule the follow-up audit. Central Office personnel will perform any follow-up audits.<br />
::d. If a follow-up audit is required, and performed, and the inspector is still deficient in record keeping or general inspection practice, a recommendation of “not meeting expectations” will be forwarded to the supervisor for MAPS, with copies of the justification forwarded to the District Construction and Materials Engineer and the State Materials Engineer for potential additional action.<br />
<br />
======123.3.1.3.2.4======<br />
The auditor has responsibility for off-system and other Federal-aid projects as may not be managed or inspected by MoDOT personnel. In these instances, the targets tests indicated above and in [[:Category:123 Federal-Aid Highway Program#Table 123.3.1.3.2|Table 123.3.1.3.2]] will be the focus of the audit. The auditor will observe and/or run companion tests as necessary. <br />
<br />
The tester should have the appropriate Technician Certification credentials. Central Office has control over the status of the tester’s Technician Certification but cannot directly affect whether an inspector is sent to an off-system project. When there are issues with the testing performance or equipment of an off-system tester, the appropriate agency (off-system project owner) should be contacted.<br />
<br />
=====123.3.1.3.3 Frequency=====<br />
The frequency at which IAS audits are to be performed is a minimum of once per year per inspector who has performed inspection on a Federal-aid project in the last 12 months. Also considered is the inspector’s Technician Certification. A reasonable effort should be made to cover as many of the test methods the inspector has performed in the last 12 months as possible.<br />
<br />
=====123.3.1.3.4 Reasonable Effort=====<br />
It is not the intent that an IAS audit be performed at predetermined uniform intervals. A reasonable effort should be made to have the audits occur on a random basis while still meeting the requirements of [[:Category:123 Federal-Aid Highway Program#123.3.1.3.3|EPG 123.3.1.3.3]].<br />
<br />
=====123.3.1.3.5 Material from an Unrelated Source=====<br />
An inspector audit may involve material from a source that is unrelated to Federal-aid work. The goal is to determine whether the inspector is capable of running the test or performing appropriate inspection. When practical, the audit will take place on a Federal-aid project, but this is not a requirement of a valid IAS audit. The auditor may obtain “audit sample” material in advance of an audit for use in the audit process. Refer to [[:Category:123 Federal-Aid Highway Program#123.3.1.5.7 Prepared Audit Standard Samples|EPG 123.3.1.5.7]].<br />
<br />
=====123.3.1.3.6 Equipment=====<br />
Each inspector assigned to be an IAS Auditor is to be fully equipped or have ready access to the equipment necessary to perform all field tests listed in [[:Category:123 Federal-Aid Highway Program#Table 123.3.1.3.2|Table 123.3.1.3.2]], except nuclear density tests, asphalt binder content with a nuclear gauge, asphalt binder content with binder ignition oven, gyratory compactor and maximum specific gravity testing equipment. This equipment is to be used on a portion of the tests performed. As a guide, it is recommended that approximately 80% of each type of field test specified be performed by the IAS Auditor using equipment other than that assigned to project personnel, except when nuclear density testing, asphalt binder content by nuclear method, asphalt binder content by binder ignition method, gyratory compactor operation and maximum specific gravity testing are used. On the remaining tests to be made, the IAS Auditor may perform the test, or participate in the sampling and testing, or witness the sampling and testing. <br />
<br />
=====123.3.1.3.7 Immediate Supervisor=====<br />
When possible, the IAS Auditor and the inspector being reviewed should not report to the same immediate supervisor.<br />
<br />
====123.3.1.4 Auditing Specified Tests====<br />
The instructions for each of the specified tests is as follows:<br />
<br />
=====123.3.1.4.1 Nuclear Density=====<br />
When nuclear density testing methods are used for project job control, the IAS Auditor is not required to perform any of those tests. However, designation of the location for the test, witnessing the test, checking calculations, and reporting is required. As indicated above, it is acceptable for the test to be run on a non-Federal-aid project or at any location where a valid test could be completed. In addition, the IAS Auditor is to review the daily standardization check for the machine being used, if the checks are required by policy. The audit report needs to state whether the standardization check was examined. If the standardization check has not been performed as required, please note in the remarks.<br />
<br />
=====123.3.1.4.2 Asphalt Binder Content=====<br />
When asphalt binder content, for normal job control, is determined by nuclear gauge or binder ignition oven, the IAS Auditor is not required to perform any of those tests. However, observing the sample preparation, testing, checking calculations, and reporting are required. When the nuclear gauge is used, the IAS Auditor is to review the statistical stability test records and the daily background check for the nuclear gauge being used. The report is to state that the statistical stability test and the background check were reviewed and found current and satisfactory, or not. The asphalt content by nuclear gauge or binder ignition oven is to be reported on the appropriate test template in SiteManager.<br />
<br />
=====123.3.1.4.3 Gyratory Compactor=====<br />
When a gyratory compactor is used for normal job control, the IAS Auditor is not required to perform any of those tests. However, if a gyratory compactor other than the one being used by the inspector is available, a split sample should be obtained and compacted on the alternate machine. In lieu of compacting a sample on an alternate machine the auditor may observe the required sample preparation, testing, and reporting. When a gyratory compactor is used, the IAS Auditor is to review the calibration records for the gyratory compactor being used. The report is to state that the calibration records were reviewed and found current and satisfactory, or not. <br />
<br />
=====123.3.1.4.4 Suitable Locations=====<br />
Independent Assurance tests may be performed at any suitable location in the field, district laboratory, or Central Laboratory in Jefferson City as condition and need dictates, unless otherwise directed.<br />
<br />
=====123.3.1.4.5 Rounding Off=====<br />
Test results are to be rounded off for reporting in conformance with the procedures set out in [[106.20 Reporting|EPG 106.20 Reporting]].<br />
<br />
=====123.3.1.4.6 Sample Preparation=====<br />
All IAS aggregate gradation tests are to be “washed” and are to include each sieve specified. The size of sample and method of sieve analysis of fine and coarse aggregate is to be in accordance with [[:Category:1001 General Requirements for Material#1001.4.1.2 Sample Preparation|EPG 1001.4.1.2]], except: (1) the size of hot bin gradation samples for bituminous mixtures shall be as shown in [http://www.modot.mo.gov/business/standards_and_specs/DIV0400.pdf Division 400 of the specifications] and (2) for coarse aggregate, the nominal maximum size of particle is to be considered as the largest sieve size on which material is retained.<br />
<br />
=====123.3.1.4.7 Obtaining the Sample=====<br />
IAS requirements for gradation, PI, or liquid limit tests on aggregates and base materials are to be fulfilled by obtaining the sample by one of the following methods.<br />
<br />
(a) By the inspector taking a sample in the presence of the IAS Auditor and then furnishing one-half of the sample to the IAS Auditor. The inspector is to perform the required tests in the presence of the IAS Auditor and report the results to the IAS Auditor. The IAS Auditor will perform the required IAS tests on the other one-half sample, recording the results obtained by both the inspector and the IAS Auditor in SiteManager.<br />
<br />
(b) By the IAS Auditor taking or bringing a sample and furnishing one-half of the sample to the inspector currently assigned to that plant or location, who will then perform the required tests and report the results to the IAS Auditor. The IAS Auditor will perform or will have previously performed the required IAS tests on the other one-half sample.<br />
<br />
=====123.3.1.4.8 Samples sent to the Central Laboratory=====<br />
The IAS Auditor may designate samples to be sent to the Central Laboratory. These samples are to be designated “IAS” in the Sample Type field of SM. The sample record is to contain the prescribed information regarding the location and shall indicate the person designating the location and performing or witnessing the sampling. The IAS Auditor will record the Sample ID(s) of such samples sent to the Central Lab, review the results, and will make a final sample record regarding the results of the inspector audit.<br />
<br />
=====123.3.1.4.9 Equipment Review===== <br />
The test equipment used by the inspector must be reviewed for status of calibration, general condition, and appropriateness for the test performed. Equipment assigned to an individual may be reviewed with the query designated in [[:Category:123 Federal-Aid Highway Program#123.3.1.3.1 Report Review|EPG 123.3.1.3.1]]. Data will be edited or updated as necessary by individuals designated by the District Construction and Materials Engineer using the Calibrated Equipment window in SM (AS-3340). The inspector is to make the initial determination of condition/calibration of the equipment and the auditor is to confirm this information. If the inspector is in error, the nature of the error should be recorded as part of the audit of the inspector. The inspector is to confirm that the calibrated equipment records are kept current, including notation of equipment taken out of service.<br />
<br />
====123.3.1.5 Test Procedures====<br />
<br />
<br />
The following tests are described as though the IAS Auditor and inspector are working on a particular project. It is not necessary that the material be taken from, or for, a particular project. The inspector will describe appropriate site selection and sampling, on the basis of the material be tested. When possible, the sampling site will be typical of that to be selected for a Federal-aid project.<br />
<br />
=====123.3.1.5.1 Grading=====<br />
<br />
The location of tests, for both embankment and subgrade preparation are to be selected so as to be typical of that which might occur on a Federal-aid project.<br />
<br />
IAS Auditor performed density tests, other than nuclear, are to be located in the very near vicinity of the density test performed by the inspector and are to be performed by the same method used by the inspector.<br />
<br />
In areas of the state where it is routine to determine that the material is too rocky to test, the IAS Auditor should ask the inspector to identify a location that cannot be tested and a location where the test is to be performed. It may be necessary to move away from the roadway in order to find a location suitable for the test.<br />
<br />
=====123.3.1.5.2 Aggregate, Sand-Soil, Soil-Cement, or Soil-Lime Bases=====<br />
<br />
IAS Auditor performed density tests, other than nuclear, are to be located in the very near vicinity of the density test performed by the inspector and are to be performed by the same method used by the inspector.<br />
<br />
Care should be taken to show the location of IAS tests by roadway, station, distance right or left of centerline or of the edge of pavement, number and nominal thickness of the lift or lifts identified shall be shown. The purpose of this part of the process, with regard to system based IAS is to confirm that the inspector is capable of making such a determination.<br />
<br />
Samples of material for gradation or PI are to be obtained at a point just prior to use, i.e., stockpile, pug mill, spreader, belt feeder or bin discharge. The place of sampling and the approximate roadway station number where the material is laid is to be shown on the report. The samples are to be taken by one of the methods described [[:Category:123 Federal-Aid Highway Program#123.3.1.4.7 Obtaining the Sample|EPG 123.3.1.4.7]].<br />
<br />
=====123.3.1.5.3 Crushed Stone or Gravel Surfacing=====<br />
<br />
Samples for gradation are to be taken at a point just prior to use. The samples are to be taken by one of the methods described in [[:Category:123 Federal-Aid Highway Program#123.3.1.4.7 Obtaining the Sample|EPG 123.3.1.4.7]].<br />
<br />
The report is to show the roadway, approximate station number where the aggregate is placed and the place of sampling if this applies.<br />
<br />
=====123.3.1.5.4 Bituminous Mixtures=====<br />
<br />
The asphalt plant inspector may obtain the IAS samples for gradation provided the IAS Auditor observes the sampling. The sample is to be split and the IAS test performed on one-half the sample. The inspector would test the other one-half of the sample and the results may be for acceptance purposes. The IAS Auditor may perform the IAS test at the project using equipment other than project equipment, except, both inspectors may use the same scale if the scale has been calibrated within the immediate past 12 months, or the IAS test may be performed in the district laboratory.<br />
<br />
Road mix gradation samples of aggregate should be taken at a point just prior to use, however, for IAS, this is not a requirement.<br />
<br />
the inspector may obtain the IAS samples for maximum specific gravity provided the IAS Auditor observes the sampling. The sample is to be split and the IAS test performed on one-half the sample. The inspector would test the other one-half of the sample and the results may be used for acceptance purposes. The IAS Auditor may perform the IAS test at the project using project equipment. Both inspectors may use the same scale if the scale has been calibrated within the past 12 months. The IAS Auditor is to review calibration records for the maximum specific gravity testing equipment being used. The report is to state whether the calibration records were reviewed and found current and satisfactory, or not.<br />
<br />
'''Volumetrics''' (specific gravity of gyratory compacted specimens) should be determined on a set of specimens (pills) compacted by the inspector using a gyratory compactor. The IAS Auditor should review the inspector’s use of the gyratory compactor. The IAS Auditor may use the specimens produced by the inspector.<br />
<br />
IAS tests of compacted SuperPave asphaltic concrete pavement, plant mix bituminous pavement or plant mix bituminous base are to be performed on the same samples taken by the project inspector. The tests may be performed in the district laboratory or the Central Laboratory. When tests are performed in the district laboratory, the test report is to show the location by roadway, station, distance and direction from centerline, and the lift designation of the course. If submitted to the Central Laboratory for testing, the identification sheet is to also show this information.<br />
<br />
When performing IAS on bituminous mixes using RAP, the combined gradation will be calculated using the RAP gradation being determined daily by the project personnel and the aggregate gradation determined from the cold feeds or the hot bins. At some batch plants, the RAP may be added prior to the hot bins. In that case, the combined gradation will be determined from the hot bins only. Project personnel should be consulted, prior to testing, to determine where the RAP is being added.<br />
<br />
If the contractor elects to use the binder ignition method to determine the combined gradation for job control, the IAS Auditor shall witness the testing process to ensure proper testing procedures are being used. <br />
<br />
=====123.3.1.5.5 Portland Cement Concrete Pavement and Base=====<br />
<br />
Aggregates are to be obtained at the batching plant from the belt or the bin discharge as they are proportioned for use and are to be taken by one of the methods described in [[:Category:123 Federal-Aid Highway Program#123.3.1.4.7 Obtaining the Sample|EPG 123.3.1.4.7]]. The place of sampling and the approximate roadway station number where the aggregate is used is to be shown on the report. For coarse aggregate produced in more than one fraction, the gradation of each fraction, percent of each used and the combined gradation shall be shown.<br />
<br />
The concrete sample for IAS for air and slump is to be from the same concrete sample taken by the project inspector for an acceptance test.<br />
<br />
When a compression testing machine is used for normal job control, the IAS Auditor is not required to perform any of those tests. However, observing the sample preparation, testing, and reporting are required. When a compression testing machine is used, the IAS Auditor is to review the calibration records for the compression testing machine being used. The report is to state that the calibration records were reviewed and found current and satisfactory, or not. <br />
<br />
When a thickness measuring device is used for normal job control, the IAS Auditor is not required to perform any of those tests. However, observing the sample preparation, testing, and reporting are required.<br />
<br />
=====123.3.1.5.6 Concrete Masonry=====<br />
<br />
Aggregates are to be obtained at the batching plant from belt or bin discharge as they are proportioned for use and are to be taken by one of the methods described in [[:Category:123 Federal-Aid Highway Program#123.3.1.4.7 Obtaining the Sample|EPG 123.3.1.4.7]]. The place of sampling, class of concrete, structure and structure elements are to be shown on the report.<br />
<br />
The concrete sample for air, slump, and cylinders is to be from the same concrete sample taken by the inspector for the acceptance test.<br />
<br />
A compressive strength test shall consist of the molding and testing of a cylinder. Molding and testing need not be performed on the same specimen. The testing of IAS comparison cylinders is to be performed on a machine independent of the machine used by the inspector, or sent to the Central Laboratory at 28 days. IAS comparison cylinders are to represent routine compressive strength tests, not tests made for a specific operational control such as form removal, heat removal, etc.<br />
<br />
=====123.3.1.5.7 Prepared Audit Standard Samples=====<br />
<br />
To accommodate the process of auditing inspectors when no project is active, or when the active project work does not include the type of work being audited, the auditor may provide previously prepared and tested samples. The inspector is prompted to run the appropriate tests on the sample as though the sample had been obtained on the project by the inspector. It is not necessary that audit sample material be specification compliant however it should be reasonably representative of the target material such that a valid test can be completed.<br />
<br />
If possible, the inspector will actually obtain a sample of the target material as the auditor observes to confirm the use of correct sampling procedure. That sample may be discarded, or the inspector can use the sample for routine job control testing. The auditor may witness the inspector sample and test any sample taken for acceptance purposes. At a minimum, the inspector will explain to the auditor the correct procedure for obtaining the sample under normal inspection practice.<br />
<br />
====123.3.1.6 Comparison of Test Results====<br />
<br />
All test results obtained by the IAS Auditor, including those not meeting specifications and those from samples submitted to the Laboratory for testing, are to be compared with the companion results obtained by the inspector using [[Independent Assurance Samples and Tests|established guidelines]] as soon as possible and the results reported. The IAS Auditor’s test result and the inspector’s test result should compare within the limits shown in [[Independent Assurance Samples and Tests|established guidelines]]. If the two tests do not compare within those limits the inspector should be found as not comparing favorably and test procedures are to be reviewed, equipment checked, and if necessary, the test repeated to determine the reason(s). Results of the audit should be reported to the project's manager and owner.<br />
<br />
====123.3.1.7 Sample Record====<br />
<br />
Results of IAS are to be reported on the appropriate form in SM with complete information shown. The reports should be submitted promptly after tests are completed, within ten working days of the determination of the final test results, when multiple tests were involved. The sample record described in Automation Section is also required.<br />
<br />
IAS tests are not to be reported as “accepted” or “rejected”. The IAS test result is not to be used for purposes of acceptance or rejection of material. When IAS testing compares with acceptance testing or when IAS confirms equipment calibrations are current and proper testing procedures were utilized, the SM report will show the status as “Compared Favorably/Compliant (IAS only)”. When IAS testing does not compare with acceptance testing or when IAS finds equipment calibrations are not current or proper testing procedures were not utilized, the SM report will show the status as “Not Compared Favore/Not Comply (IAS only)”.<br />
<br />
The following information is also to be on the IAS report:<br />
<br />
:The report shall state that the calculations were checked and are on file in the district office. It will not be necessary for intermediate calculations to be shown on the report, since only the final result for the particular test is required, however all calculations shall be carefully checked for accuracy and maintained on file in the district office.<br />
[[image: 123.3.1.7.jpg|right|350px|thumb|'''<center>The report shall state that the calculations were checked and are on file in the district office.</center>''']]<br />
<br />
:The report shall state that test results of the IAS were compared with the inspector’s test results. The sample record number (when used), date performed and test results of the companion tests are to be shown on the report. In addition, the comparison difference between the tests is to be shown for each test result obtained. The report shall state whether the comparison was favorable or not favorable. If the comparison was not favorable, the probable reason(s) and any corrective action taken shall be shown on the report. If the acceptance test does not have a sample record number, other information shall be shown to identify the comparison test. When comparison testing is performed in whole or as part of an audit, the appropriate SM template should be used.<br />
<br />
:If the IAS Auditor witnessed a test, state what parts of the tests were observed and include the statement “location designated, procedure and computations checked by the IAS Auditor.” The name of the project inspector performing the test is to be shown.<br />
<br />
:The report shall state where the tests were performed (field, district laboratory, or Central Laboratory) and what equipment was used (district Material’s or belonging to field personnel), e.g. “The test was performed in the district Laboratory using Materials equipment”.<br />
<br />
:Each audit sample record is to be authorized by the IAS inspector or the District Construction and Materials Engineer.<br />
<br />
:The IAS Inspector must be the creator of the sample record.<br />
<br />
====123.3.1.8 Progress Report of Independent Assurance Process====<br />
<br />
A monthly progress report is submitted to the State Construction & Materials Engineer, The Assistant State Construction & Materials Engineer, The FHWA, District Construction & Materials Engineers and the IAS Audit Group. The report outlines the goals and progress of district and Central Office’s auditors. In addition this report is used to report the IAS Tracker Measure. The Construction and Materials Liaison Engineer or his/her designated person prepares the report.<br />
<br />
Any instances of non-compliance are reported to the subject’s supervisor, FHWA and the District Construction & Materials Engineer.<br />
<br />
===123.3.2 Independent Assurance Samples and Tests (IAS) Project Based===<br />
<br />
Refer to [[Independent Assurance Samples and Tests|EPG Independent Assurance Samples and Tests]].<br />
<br />
===123.3.3 Federal-Aid Acceptance Sampling and Testing (FAST)===<br />
<br />
The following information establishes procedures for Federal-Aid Acceptance Sampling and Testing (FAST) of aggregates for all Federal-Aid projects awarded and administered by MoDOT. They apply to aggregates on Federal-Aid projects on which the Department performs the acceptance sampling and testing. In addition, if a [[:Category:136 Local Public Agency (LPA) Policy|local public agency]] receives federal funds from MoDOT but does not specify MoDOT QC/QA practices, the guidelines in the [[Off-Systems Guide Schedule for Federal-Aid Acceptance Sampling and Testing (FAST)|Off-Systems Guide Schedule for Federal-Aid Acceptance Sampling and Testing (FAST) table]] should be followed. The acceptance sampling and testing procedures for other materials and construction processes are to be as shown in other articles in the Engineering Policy Guide. These procedures do not change the sampling and testing requirements for aggregates at the production source. <br />
<br />
====123.3.3.1 General Procedures====<br />
<br />
An inspector who takes Independent Assurance Samples (IAS) for these materials on a project is not to perform the FAST for the same material on the same project. The inspector may take a sample and furnish one-half the sample to the FAST inspector who will then perform the required tests and report the results as a FAST. Whenever possible, the IAS inspector and the FAST inspector of a particular sample should not report to the same immediate supervisor. <br />
<br />
An inspector performing [[:Category:1000 MATERIALS|process control tests]] (at quarry, source, etc.) may also perform FAST on the same aggregates. An IAS inspector may take FAST samples of aggregates on projects other than those on which he is taking IAS. <br />
<br />
The frequency at which FAST is to be performed should generally conform to the [[Federal-Aid Acceptance Sampling and Testing|guide schedule]].<br />
<br />
FAST of aggregates are to be obtained at the last point of handling prior to mixing with other materials or incorporation into the work. The district construction and materials engineer will determine if samples are taken from the pugmill or loaded truck at the pugmill, from the belt or bin discharge at the batch plant, from the roadway, or at other points. <br />
<br />
The FAST is to be performed as soon as practicable after sampling. The district may determine the frequency at which gradations will be performed as washed tests except that if a FAST is performed on one-half of an IAS, it is to be washed. The size of sample and method of sieve analysis of fine and coarse aggregate is to be in accordance with [[:Category:1002 Aggregate for Asphaltic Concrete|EPG 1002 Aggregate for Asphaltic Concrete]]. <br />
<br />
For coarse aggregate, the nominal maximum size of particle is to be considered as the largest sieve size on which material is retained. The sample size of fine aggregate may have to be adjusted in order to comply with the requirement in [[:Category:1002 Aggregate for Asphaltic Concrete|1002 Aggregate for Asphaltic Concrete]], i.e., the fraction retained on any sieve at the completion of the sieving operation shall not exceed 4 grams per square inch (6 kg/m<sup>2</sup>) of sieving surface. As a guide only, it is suggested approximately 400 grams be used as a sample size for fine aggregate for portland cement concrete ([http://modot.mo.gov/business/standards_and_specs/Sec1005.pdf Sec 1005.3]) and approximately 100-150 grams for all other fine aggregate gradations. <br />
<br />
Test results are to be rounded according to information contained in [[106.20 Reporting|EPG 106.20 Reporting]].<br />
<br />
====123.3.3.2 Report====<br />
<br />
Results of FAST are to be reported using SM and are to provide complete information. The sample record should be created and reports submitted promptly after tests are completed, within ten working days at the latest. <br />
<br />
The sample record should be created according to [http://contribute.modot.mo.gov/business/materials/pdf/vol_3/AS3510.pdf Automation Section 3510] with the following information provided as clarification of specific issues. <br />
<br />
The '''Status''', when the sample record is complete will be set to FAST Compliant or FAST Deviant. Any other status is incorrect. <br />
<br />
The '''Sample Type''' will be set to PJ (Proj. F.A.S.T.). <br />
<br />
The '''Acceptance Method''' will be SATE (Sample and Test). <br />
<br />
The '''Producer/Supplier''' shall be the original producer of the material. For example, the quarry, not the ready-mix plant, would be shown. <br />
<br />
'''Smpld From''' shall show the location of sampling, i.e., "stockpile, bin discharge or roadway". <br />
<br />
'''Smpl Origin''' shall show the origin of the sample, i.e., “project, Anytown Ready Mix”. <br />
<br />
The quantity may be shown on the contract tab when the FAST inspector knows the appropriate quantity to report and is able to confirm that the material complies with all appropriate specifications, not just those part of the FAST inspection process. Care must be taken to avoid duplicate reporting of quantity. This option is provided to allow more efficient use of SM, and the quantity data reported in this manner is not considered to have a direct relationship to the FAST process. <br />
<br />
When a FAST is one-half of an IAS, the report is to identify the IAS either by complete information as to project number, date sampled, and complete location of sampling including station number, all included in the Remarks or by an identification number. For example, the FAST report could carry an identifying note such as "Test performed on one-half of IAS 1-93-20" as part of the test template. <br />
<br />
The report shall state either “Accepted/Complete” which means the material complies with the specifications or ”Fail/Rejected” which means material deviates from specifications. If a specification deviation occurs, retests should be made as soon as possible. Any corrective action to be taken will be determined by the district. Reports showing specification deviations are to include full information including results of retests, if made, cause of deviation, if known, what corrective action was taken, and the amount and disposition of this material. <br />
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Where material is being used on more than one Federal-Aid project, such as at a ready mix concrete plant, the frequency of performing FAST may be determined by combining the tons of that type aggregate being used. An example of this would be a ready mix plant producing concrete for three Federal-Aid projects; FAST of coarse aggregate would be obtained when 1,000 tons (megagrams) of coarse aggregate had been used on all projects combined. A report of this test would then be issued for each of these projects. When FAST is performed on one-half of an IAS, only the test report issued to the project for which the IAS was taken is to contain remarks identifying the IAS. <br />
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Distribution of the report shall be as is normally appropriate for the material tested.</div>Jonesjb