REVISION REQUEST 4191

902.4.1 General (MUTCD Section 4D.01)

Support. The features of traffic control signals of interest to road users are the location, design, and meaning of the signal indications. Uniformity in the design features that affect the traffic to be controlled, as set forth in this Manual, is especially important for the safety and efficiency of operations.

Traffic control signals can be operated in pretimed, semi-actuated, or full-actuated modes. For isolated (non-interconnected) signalized locations on rural high-speed highways, full-actuated mode with advance vehicle detection on the high-speed approaches is typically used. These features are designed to reduce the frequency with which the onset of the yellow change interval is displayed when high-speed approaching vehicles are in the “dilemma zone” such that the drivers of these high-speed vehicles find it difficult to decide whether to stop or proceed.

EPG 902.23.1 contains information regarding traffic control signal operation.

Standard. The design and operation of traffic control signals shall take into consideration the needs of all modes of traffic including access and safety.

When a traffic control signal is not in operation, such as before it is placed in service, during seasonal shutdowns, or when it is not desirable to operate the traffic control signal, the signal heads shall be covered, turned, or taken down to clearly indicate that the traffic control signal is not in operation.

If a traffic control signal head is not in operation and has a yellow retroreflective strip along the perimeter of its signal backplate (see the fifth option paragraph of EPG 902.4.6), the signal head, shall be covered. If a cover is placed over a traffic control signal head that is not in operation, the entire signal head, including the signal faces and backplate shall be covered.

Standard. A traffic control signal shall control traffic only at the intersection or midblock location where the signal faces are placed.

Guidance. Midblock crosswalks should not be signalized if they are located within 1,000 feet from the nearest traffic control signal, unless supported by an engineering study or engineering judgment that indicates safe and efficient operation of the closely-spaced traffic control signals can be achieved.

Midblock crosswalks should not be signalized if they are located within 100 feet from side streets or driveways that are controlled by STOP signs or YIELD signs, unless supported by an engineering study or engineering judgment that considers restricting turning movements from the side street or driveway to eliminate conflicts with pedestrian and bicyclist movements.

Engineering judgment should be used to determine the proper phasing and timing for a traffic control signal. Since traffic flows and patterns change, phasing and timing should be reevaluated regularly and updated if needed.

Traffic control signals within ½ mile of one another along a major route or in a network of intersecting major routes should be coordinated, preferably with interconnected controller units. Where traffic control signals that are within ½ mile of one another along a major route have a jurisdictional boundary or a boundary between different signal systems between them, coordination across the boundary should be considered.

Support. Signal coordination need not be maintained between control sections that operate on different cycle lengths.

EPG 902.6.19 and EPG 913.4.9 contain information about coordination of traffic control signals with grade crossing signals.

REVISION REQUEST 4202

236.5.29 License Plate Readers

Automated License Plate Readers (LPRs) and Pan-Tilt-Zoom cameras (PTZs) are an increasingly popular way for law enforcement to better locate vehicles associated with criminal activity. The deployment of these devices on Commission right of way require FHWA approval and shall not create a safety risk for the traveling public or interfere with MoDOT’s ability to maintain and operate the transportation system.

The general process for LPR and PTZ requests is outlined in EPG 941.10.

It is the requesting law enforcement agency’s responsibility to contact MoDOT’s local traffic permit specialist to initiate the permitting process, after approval from Department of Public Safety (DPS) has been received. The local district traffic representative will work with the applicant through the permitting process.

Once the district traffic staff determine the LPRs or PTZs are eligible to be deployed on Commission right of way, the district traffic staff will forward the drafted permit via the permit database to Central Office Right of Way (COROW). CO ROW will then gather the following items to seek FHWA approval:

Cost estimate including the device and pole, and fair market value of the device location
Environmental clearance - categorical exclusion approval

Once COROW gathers the items listed above, they will include the following items in their submittal to FHWA for approval:

FHWA LPR Nonhighway Use Request Letter
DPS approval letter
Roles and Responsibilities document
Plans including type and location of equipment to be installed

Upon receiving FHWA approval, COROW will upload the FHWA approval documentation in the permit database and notify the district traffic staff they may proceed with issuing the permit. If FHWA does not approve, the permit cannot be issued.

941.10 Automated License Plate Readers and Pan-Tilt-Zoom Cameras

Additional Resources

License Plate Readers SharePoint Site (MoDOT Access Only)

LPR Flowchart and Installation Locations

General LPR Typical Details

Flock LPR Typical Details.

Automated License Plate Readers (LPRs) and Pan-Tilt-Zoom cameras (PTZs) are an increasingly popular way for law enforcement to better locate vehicles associated with criminal activity. These high-tech devices allow law enforcement agencies to compare plate numbers against those of stolen vehicles and vehicles driven by individuals with expired licenses, an active warrant, or involved with terrorist activities.

The deployment of these devices on Commission right of way shall not create a safety risk for the traveling public or interfere with MoDOT’s ability to maintain and operate the transportation system. All costs associated with the installation and maintenance of the LPRs and PTZs will be the responsibility of the applicant. The following guidance applies to any LPR or PTZ installed on Commission right of way.

941.10.1 Approval Process

The general process for LPR and PTZ requests are outlined in the LPR Flowchart. Law enforcement agencies must request approval, in writing, for deploying LPRs and PTZs from the Director of the Department of Public Safety. Requests are to be on the law enforcement agency letterhead and emailed to the Department of Public Safety at dpsinfo@dps.mo.gov.

The Department of Public Safety (DPS) provides approval for the use of LPR and PTZ devices. MoDOT only facilitates the administration of work by others on Commission right of way. MoDOT’s permitting process will be followed for the constructability and maintenance of the devices to ensure the safety of the traveling public. If an issue is identified through our normal permitting process and cannot be resolved, a permit for this work will not be issued.

It is the requesting law enforcement agency’s responsibility to contact MoDOT’s local permit specialist to initiate the permitting process, after approval from DPS has been received. Contact information for MoDOT’s local permit specialists can be found using the District Permit Maps.

The local district traffic representative will work with the applicant through the permitting process. The permit request submittal must include:

An aerial image, or map, depicting all the individual LPR locations included in the submittal.
An aerial image for each LPR location included in the submittal clearly showing where the proposed installation with respect to the roadway and other structures on the right of way.
A set of drawings, or plans, showing the hardware and their installation details proposed on the right of way, which must be signed and sealed by a Missouri Professional Engineer (P.E.).
This applies to stand alone installations as well as installations on approved existing structures on right of way, such as signal and sign truss uprights.
Executing a Roles and Responsibilities document to specifically address the expectations of maintaining the devices being installed.
A plan to provide electricity to the equipment as well as retrieving data from the equipment.
A traffic control plan for any proposed work on the right of way to notify and guide motorists safely through the activity area.
A surety deposit or performance bond to insure satisfactory work, accepted by MoDOT.

A separate permit may be provided for the applicant, or their consultant, to access the right of way to collect information needed to develop a set of plans for installing the devices.

941.10.2 Location

When receiving a request, the district traffic staff will work with the law enforcement agency to determine if there are acceptable locations for the proposed installations off MoDOT right of way. If there are no appropriate locations off of right of way, the district traffic staff will work with the agency to determine if the LPRs and PTZs requested can be deployed on Commission right of way.

LPR and PTZ installations on Commission right of way shall only monitor traffic on MoDOT roadways and shall not be used to monitor off system roadways, such as county, city, or private facilities.

Once the district traffic staff determine the LPRs or PTZs are eligible to be deployed on Commission right of way, the district traffic staff will forward the drafted permit via the permit database to Central Office Right of Way (COROW). See section 236.5.29 for COROW’s review and process for requesting FHWA’s approval.

Upon receiving FHWA approval, COROW will upload the FHWA approval documentation in the permit database and notify the district traffic staff they may proceed with issuing the permit. If FHWA does not approve, the permit cannot be issued.

941.10.2.1 LPR and PTZ Non-Permanent Installations - Speed Enforcement Trailers

The only form of non-permanent structure that LPR and PTZ devices may be deployed on, when placed on Commission right of way, are speed trailers. However, speed trailers shall only be deployed for the primary purpose of speed enforcement and not for the primary purpose of deploying LPR and PTZ devices. When speed trailers are deployed, the electronic speed message must be active and the unit deployed and delineated in accordance with EPG 907.8 Speed Trailers Deployed by Others.

941.10.2.2 LPR and PTZ Permanent Installations

To ensure LPR and PTZ devices do not represent an added risk to the traveling public, there are defined installation locations which are acceptable on Commission right of way. Acceptable installation locations include:

Only deployed on the right side of the roadway outside of the shoulder.
On MoDOT traffic signal upright poles, except in instances where deployment will interfere with other devices already attached to the pole.
On MoDOT overhead sign truss upright poles.
On any non-breakaway structure owned by a third party, with the written permission of the third party.
On independent support behind barrier (installed and maintained by requesting agency or their LPR vendor) in accordance with the guidance in EPG 941.10.2.2.3.
On independent breakaway support that has been crash tested by the LPR vendor and approved by MoDOT. See EPG 941.10.2.2.3 for approved systems.

Locations where LPR and PTZ devices shall not be installed include, but are not limited to:

Any installation in the median / left side of a divided highway.
Any overhead location.
On any existing structure on right of way which has a breakaway design, whether it is owned by the Commission or a third party.
Any bridge structure.
Any location that already has a device installed.
Any location that may interfere with MoDOT's ability to manage the transportation system.

MoDOT does not allow the deployment of LPR and PTZ devices overhead or in the median as these locations would result in increased impact on the safety and mobility of the traveling public when performing installation and maintenance activities. LPR and PTZ devices are not permitted on any existing structure which is designed as a breakaway device on Commission right of way, regardless of ownership, as the addition of these devices could negatively impact the performance and safety of the breakaway structure.

There are three methods identified for deploying LPR and PTZ devices on Commission right of way, all of which must be approved by MoDOT and installed under a MoDOT permit:

LPRs and PTZs installed on MoDOT structures.
LPRs and PTZs installed on non-MoDOT structures.
LPRs and PTZs installed on new stand-alone structures.

941.10.2.2.1 LPRs and PTZs Installed on MoDOT Structures

LPRs and PTZs can be attached to MoDOT’s existing traffic signal upright poles and existing sign truss upright poles upon review and approval by MoDOT.

Green Box Indicates Acceptable Mounting Location on a
Traffic Signal, Red Boxes are Unacceptable Mounting Locations

Green Box Indicates Acceptable Mounting Location on an Overhead Sign Truss,
Red Boxes are Unacceptable Mounting Locations

941.10.2.2.2 LPRs and PTZs Installed on non-MoDOT Structures

There are some structures that have been permitted on Commission right of way which are owned by other entities, such as structures for weigh station bypass equipment or utility poles. Law enforcement agencies have the option to acquire approval from the owners of the structures to utilize them as supports for their LPR and PTZ devices if they meet the following criteria:

The structure must be reviewed and approved by MoDOT for use.
Written permission from the owner of the structure must be acquired and supplied to MoDOT.
Any structure which is of a breakaway design, such as roadway lighting poles or highway signs, are not acceptable support structures.
Installation location criteria listed in EPG 941.10.2.2 also apply to these structures.

941.10.2.2.3 LPRs and PTZs Installed on New Stand-Alone Structures

To limit the number of structures on Commission right of way, opportunities to locate the LPRs and PTZs off of right of way is the preferred option, followed by an installation location on an existing structure already on right of way. If it is determined a new stand-alone structure is required to facilitate the LPR and PTZ deployment, the following guidance shall be followed:

The district traffic shall work with the local agency to find a location which meets the requirements outlined on the General LPR Typical Details or Flock LPR Typical Details.
Stand-Alone LPR and PTZ structures shall be properly spaced away from other traffic control devices, which can include but are not limited to highway signs, traffic signal, roadway lighting poles, etc.:

○ No closer than 200 feet upstream of a traffic control device.

○ No closer than 50 feet downstream of a traffic control device.

Installation and maintenance access should be via adjacent private property or secondary roadways for divided highway, unless physically impossible.

REVISION REQUEST 4213

109.12 only

The primary purpose of a change order is to document a supplemental change to the contract. The official definition, as stated in Sec 101, is as follows:

Change Order - A written order from the engineer to the contractor, as authorized by the contract, directing changes in the work as made necessary or desirable by unforeseen conditions or events discovered or occurring during the progress of the work.

The second most primary purpose of the change order process is to ensure proper authority has been granted before proceeding with revisions in quantities or changes in scope of work, design concept, time or specifications. Changes in scope should be limited to the original intent, purpose and limits (length and width) of the job. In instances where proposed changes in scope go beyond these original job parameters, the change order shall be considered a major change order (Sequence 4). Significant scope changes require the State Construction and Materials Engineer to discuss the requested changes with the Asst. Chief Engineer prior to granting approval.

Change orders must have approval at all required levels before the work proceeds. Exceptions are granted for routine or minor changes, or emergency revisions for which verbal approval has been granted. In rare cases it may be necessary to proceed with emergency measures without prior approval. In such cases, verbal approval should be sought as soon as practicable. Indicate in the DWR remarks the name of the individual who provided verbal approval. For change orders that provide payment for additional work, all attempts should be made to complete the process promptly so that the contractor can be compensated at the end of the pay period in which the work was performed.

Design Changes - When the change order is a result of a design change, all appropriate design criteria should be reviewed in coordination with the Transportation Project Manager. If the design criteria cannot be met, a Design Exception is required. See EPG 131.1.4.

Environmental Change Orders - Any design changes that include disturbance of new areas on the project, or that include any other unplanned environmental impacts, should be reviewed by the Project Manager to determine if a request for environmental services is necessary prior to implementation.

Job Order Contract Change Orders - Job Order Contracts have unique contract terms that limit spending to a budgeted amount and often include pre-approved time extensions. Reference EPG 147.3.9 Change Order Approvals for additional guidance on administration of change orders for Job Order Contracts.

131.1.1 When to Complete a Design Exception

Forms

● Design Exception Information Form

● Vertical Clearance Design Exception Coordination with SDDCTEA

A design exception documents design elements of an improvement that vary from general guidance on engineering policy. In most cases, the need for an exception results from an inability to reasonably meet the design criteria. The determination to approve a project design that does not conform to the minimum criteria is to be made only after due consideration is given to all project conditions such as maximum service and safety benefits for the dollar invested, compatibility with adjacent sections of roadway and the probable time before reconstruction of the section due to increased traffic demands or changed conditions.

An approved exception documents the engineering-based determination that variance from MoDOT’s published 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.

When there is doubt whether a design exception is required, the Assistant State Design Engineers, Assistant State Bridge Engineer, Structural Liaison Engineer (SLE), or the Design Liaison Engineer (DLE) for the district should be consulted.

A design exception is encouraged whenever it is feasibly or technically impossible to reasonably meet the minimum 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.

An approved exception is not a request for permission; rather, it simply documents deliberate variances from general engineering policy.

The Federal Highway Administration (FHWA) Design Decision Documentation and Mitigation Strategies for Design Exceptions may be used in the development of the design exception.

131.1.2 The 10 Controlling Criteria

There are 10 controlling criteria that the FHWA has identified as the most important or critical elements for the design of projects on the National Highway System (NHS). FHWA only approves design exceptions for the controlling criteria listed in Table 131.1.2 when it has determined that a project is a Project of Division Interest (PODI) with Design Exception selected.

The controlling criteria, which vary based upon the type of route and design speed, are described below:

**Table 131.1.2 Controlling Criteria**
NHS with Design Speed > 50 mph	NHS with Design Speed < 50 mph	Non-NHS
Design Speed	Design Speed	(No Controlling Criteria)
Design Loading Structural Capacity	Design Loading Structural Capacity
Lane Width
Shoulder Width
Horizontal Curve Radius
Superelevation Rate
Stopping Sight Distance
Maximum Profile Grade
Cross Slope
Vertical Clearance

A design exception approved only by MoDOT is required for all other non-complying design elements on projects which are designated for federal involvement for design exceptions and for all non-complying design elements on all other projects not designated for federal involvement for design exceptions.

131.1.3 Approval Requirements

Table 131.1.3 Design Exception Required Approvals
Category	PODI Designated	Controlling Criteria*	FHWA	MoDOT
NHS	Yes	Yes	✓	✓
	Yes	No		✓
	No	Yes or No		✓
Non-NHS	Yes or No	N/A		✓
* Applicable Controlling Criteria as indicated in EPG 131.1.2.

131.1.3.1 Projects of Division Interest (PODI)

See EPG 123.1.1 FHWA Oversight - National Highway System for information on federal involvement on projects and for the PODI matrix.

131.1.4 The Design Exception Process

Requests for design exceptions are submitted when the need first arises; however, they may be submitted at any time and specifically along with the conceptual study, preliminary plan, right of way certification, or final plans. All design exceptions should be approved prior to and submitted with the plans, specifications, and estimate (PS&E). In general, it is best to identify, consider, and execute the design exception as early as practical in the design process. When a design change is required during construction, the Resident Engineer should contact the Transportation Project Manager (TPM). If that design change has elements that do not meet design standards, a design exception is required. The normal design exception process is followed.

When the need for a design exception has been identified, the TPM, Structural Project Manager (SPM), or consultant representative is responsible for completing the standard 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. 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.

Project managers (consultant, transportation or structural) 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 current policies. Since engineering policy is established through a collaborative effort, it is critical to engage all appropriate staff when making the decision not to meet policy. While completing the form, communication with the appropriate staff, including the DLE, 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.

Central Office staff should be consulted and provide review of the draft design exception prior to district approval. Design exceptions involving safety related items (see EPG 131.1.5) should be reviewed by the District Traffic Engineer and/or Highway Safety and Traffic Division prior to district approval. For design-bid-build projects, a final copy of the design exception is saved in eProjects using the appropriate content type: DE Design Exceptions, with all necessary checkboxes for Type of Exception checked. Staff should include any pertinent information in the Comments Section within the eProjects metadata. For design-build projects, approved design exceptions incorporated into the project are saved in the design-build projects SharePoint site in an Approved Design Exceptions folder.

PODI design exceptions are processed through the DLE for the State Design Engineer and FHWA signatures of approval. The DLE provides the electronic copy of the fully approved design exception back to the TPM for placement in eProjects.

FHWA reserves the right to audit the design exceptions of any federal aid project regardless of level of oversight.

131.1.4.1 The Development, Concurrence and Approval Process

In addition to the applicable process requirements described below, vertical clearance design exceptions on the interstate must also follow the additional requirement described in EPG 131.1.7 Deficient Vertical Clearances on Interstates.

131.1.4.1.1 Roadway Design Exceptions

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:

Conceptual Approval:

The TPM working with the Consultant Project Manager, if applicable, submits the design exception information form and supporting information to the DLE, the District Design Engineer (DDE), FHWA (if applicable) and any other pertinent district and division staff.
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.
The TPM works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.
The TPM submits the design exception including all supporting documentation in a single pdf file for signature according to the flowchart below.

Formal Approval:

Signatures for approval should be obtained in accordance with the following flowchart:

alt=Flowchart Start - Need for design exception (DE) identified - Go to Process 1 Process 1 MoDOT TPM (and consultant PM, if applicable) obtain conceptual approval of DE – confer with District, Divisions, and FHWA (if applicable) - Go to Process 2 Process 2 - DE revised based on conceptual approval comments - Go to process 3 Process 3 - DE reviewed by DLE - Go to Decision 1 Decision 1 - Is the project designed by a consultant? - If yes, go to Process 4, If no, go to Process 5 Process 4 - Consultant PM signs DE - Go to Process 5 Process 5 - TPM signs DE - Go to Process 6 Process 6 - DLE signs DE - Go to Process 7 Process 7 - TPM obtains District Engineer Signature - Go to Decision 2 Decision 2 - Is FHWA approval required by EPG 131.1.4? If yes, go to Process 8. If no, go to End. Process 8 - TPM sends DE to DLE - Go to Process 11 Process 9 - DLE obtains State Design Engineer signature - Go to Process 10 Process 10 - DLE obtains FHWA signature - Go to Process 10 Process 11 - DLE returns DE to TPM - Go to End End - TPM stores DE in eProjects

131.1.4.1.2 Bridge Design Exceptions

The following process should be used for design exception submittals relating to bridge items:

Conceptual Approval:

The SPM, or the SLE working with the Consultant Project Manager submits the design exception form to the Assistant State Bridge Engineer, the DLE, the Transportation Project Manager, FHWA (if applicable) and any other pertinent district and division staff.
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).
The SPM/SLE works with staff to appropriately address or resolve comments, concerns or objections and finalizes the design exception.
The SPM/SLE submits the design exception including all supporting documentation in a single pdf file for signature according to the flowchart below.

Formal Approval:

Signatures for approval should be obtained in accordance with the following flowchart:

131.1.4.1.3 Both Roadway and Bridge Item Related Design Exceptions

Occasionally, both roadway and bridge items will need to be included. In these instances, the TPM and the SLE/SPM 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.

131.1.4.2 Issue Resolution

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/SPM will remain the primary contact to address any request for additional information or consideration.

131.1.5 Completing the Design Exception Information Form

Whenever engineering policy cannot be met, data for only those non-standard items is listed on the form. 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 location (limits) associated with the solution, the existing condition (if applicable), the standard design criteria for that feature, and the proposed design solution. The column shown for the existing condition is not applicable to new construction. The appropriate values for desired design criteria are shown in the third 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 EPG 200 Geometrics articles. Design criteria for 3R and 4R projects are discussed in EPG 128 Conceptual Studies. The criteria for proper access management can be found in EPG 940 Access Management.

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 Section 4(f) or 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.

In general all design exceptions should include the following:

Specific design criteria that will not be met.
Existing roadway characteristics.
Alternatives considered.
Comparison of the safety and operational performance of the roadway and other impacts such as right-of-way, community, environmental, cost, and usability by all modes of transportation.
Proposed mitigation measures.
Compatibility with adjacent sections of roadway.

Note: The level of analysis should be commensurate with the complexity of the project.

In addition to the information above, exceptions for the Design Speed and Design Loading Structural Capacity criteria should include the following information;

Design Speed exceptions:

Length of section with reduced design speed compared to overall length of project
Measures used in transitions to adjacent sections with higher or lower design or operating speeds.

Design Loading Structural Capacity exceptions:

Verification of safe load-carrying capacity (load rating) for all state unrestricted legal loads or routine permit loads, and in the case of bridges and tunnels on the interstate, all federal legal loads.

For design exceptions related to existing conditions, a review of the existing condition crash history is required. The review should focus on crash types to which the design element may relate with a special consideration to fatal and injury crashes. A summary report of the crash information is acceptable if the volume of the data is excessive. Specific attention should be paid to design elements that have a direct impact on safety. Examples of such design elements include, but are not limited to, the following: design speed, stopping sight distance, passing sight distance, lane width, shoulder width, shoulder type, rumble strips, turn lanes, access management requirements, bridge approach rail, horizontal alignment, vertical alignment, grade, horizontal clearance, vertical clearance, guardrail, etc.

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:

Calculate the expected change in crashes from existing conditions to standard design conditions.
Calculate the expected change in crashes from existing conditions to the proposed design.

The proposed design should take into account any design exceptions as well as any additional safety features above and beyond the standard design.

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 every facility type. If a feature is not addressed in the manual, a statement should be included on the design exception stating that fact. For features not addressed in the HSM, a qualitative discussion may be included.

131.1.6 Revising an Approved Design Exception

Changes in project scope or design criteria can result in changes to design exceptions that have previously been approved. In these cases, a revised design exception must be completed and approved (as described above). The reasoning on revised design exceptions should address the changes and an explanation of the circumstances leading to the revision. The original design exception should accompany the revised information in order to illustrate the changes.

131.1.7 Deficient Vertical Clearances on Interstates

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 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 FHWA has agreed that all exceptions to a 16 foot (16') vertical clearance standard for the rural Interstate routes or on a single routhe through urban areas must be coordinated with the 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:

For a vertical clearance over any interstate highway that will be less than 16 ft. meeting the above criteria, the district submits to the Design Division a completed SDDCTEA Interstate Vertical Clearance Coordination Form along with a Design Exception for vertical clearance.
The DLE emails the Bridge Inventory Analysts and requests the Structure NBI number for box 2 on the Vertical Clearance Design Exception Coordination with SDDCTEA Form.
Concurrent with the submission or routing of the Design Exception, the DLE submits the SDDCTEA Form to the SDDCTEA and copies FHWA. This may be done electronically using the contact information on the Vertical Clearance Design Exception Coordination with SDDCTEA.
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, fax, or email. 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.
The DLE informs FHWA as to the final outcome of the SDDCTEA request.

REMOVED CAT LINK!!!!

UPDATING LINKS!!!!

Forms Box EPG 139 from d1 https://epg.modot.mo.org/forms/general_files/DE/DB-202a_Design_Exception_Summary.xlsx form d2 https://epg.modot.mo.org/forms/general_files/DE/DB-202b_Design_Exception_Form.docx

Forms Box EPG 136.7.2.7 Design Exception Information form[ https://epg.modot.mo.org/forms/general_files/DE/DesignExceptionInformationForm.docx

REVISION REQUEST 4220

751.8.1.5 Precast Culvert

General

All MoDOT cast-in-place (CIP) concrete box culverts are allowed to be constructed using alternate precast concrete box culvert sections in accordance with Sec 733, unless specified otherwise. Requirements for submitting special or modified designs are described in Sec 1049. Precast split-box designs in accordance with ASTM C1786 with or without modification are not an acceptable precast alternative.The converse is not true and precast concrete box culverts may be specified only. Pay items and quantities shall remain unchanged from those typically used for CIP concrete box culverts. When a box culvert is required to be constructed using precast concrete box culvert sections because of an accelerated timeline for construction, pay item and quantity of the precast box culvert shall be based on the length of the precast culvert to the nearest foot measured along the geometrical center of the culvert floor.

Pedestrian Box

Where a precast concrete box culvert could be used as a pedestrian (or “people”) box for walk-through or bicycle path, having multiple joints typically spaced at not greater than 6 ft. may be unacceptable due to tripping hazards, ponding/freezing (settlement of many smaller length sections) or uncomfortable riding surface. Consideration should also be given to special waterproofing or non-corrosive water stops for watertight construction joints.

Multi-Cells

In multi-cell precast construction the staggered placement of units should be avoided. Staggering units results in an irregular end section that loses continuity over the interior wall(s).

Culvert Ties

Precast box culvert ties in accordance with Sec 733 and Std. Plan 733.00 shall be required for the same reasons as concrete collars are required for CIP concrete box culverts. Typically the regular strength connections details should be used. The extra strength connection details shall be used for special cases requiring higher strengths or greater durability, for example when connecting energy dissipating baffles rings or when under low fills and a roadway. If a precast box culvert is required because of an accelerated timeline and collar beams would otherwise be required then culvert ties shall be specified with the cost of ties being considered completely covered by the contract unit price for the precast box culvert.

1049.2 Procedure

Inspection and reporting of coarse aggregate, fine aggregate, cement, fly ash shall be as appropriate for those materials.

Prior to concrete being poured, confirm the amount and placement of reinforcement. The amount and placement of welded wire fabric is to be as specified in ASTM C 1577 as applicable.

Compressive tests may be made on either concrete cylinders or cores drilled from the wall of the sections at the option of the manufacturer. If the manufacturer chooses to take cylinders and they fail, the manufacturer then has the option to core sections for possible acceptance.

Cylinders must be made in accordance with AASHTO T 280 and must be capped.

Acceptance cylinders are the responsibility of the manufacturer. An inspector’s job is to review the results for adequacy. It is good procedure to randomly validate the manufacturer results by making cylinders for comparison.

Cores in accordance with AASHTO T 280 must be both capped and lime cured.

The finished sections are to be examined for conformance to dimensions, workmanship and marking. All permissible variations are specified in ASTM C 1577.

Each section shall be marked as follows by the manufacturer by indenting into the concrete or with waterproof paint:

(a) Box section span, rise, table number, design earth cover and specification designation.

(b) Date of manufacture.

(c) Name or trademark of the manufacturer.

(d) Each section shall be clearly marked by indentation on either the inner or outer surface during the process of manufacturer so that the location of the top will be evident immediately after the forms are stripped. In addition, the word "top" shall be lettered with waterproof paint on the inside top surface.

(e) If the manufacturer is allowed to produce under an approved QC program, each section considered by the manufacturer to be specification compliant will be marked by the manufacturer with the indicator required by the QC program. Sections rejected by the manufacturer may be marked or handled in accordance with the QC program but the rejection must be clearly indicated.

(f) If the manufacturer is allowed to produce under an approved QC program, each section to be shipped will be marked by the manufacturer with the Sample ID number provided by the district. If the producer has marked a piece with a Sample ID number, and the section is found to be unacceptable during an audit, the Sample ID number must be neatly obliterated.

Sections accepted by MoDOT inspection are to be marked with "OK-MoDOT" by the inspector. Rejected sections are to be marked with a single vertical mark, near the manufacturers marking and shall be made with weather resistant marking material.

Any modification of a unit, other than constructing a box unit exactly as described in the specifications, is considered a special design, including any pipe cutouts or drainage holes to be made in the unit for any reason, whether prior to, during, or after final placement on site. Any special or modified designs submitted for approval must have been reviewed and sealed by a professional engineer, registered in Missouri, and representing the contractor or producer. Requirements for submitting special or modified designs are described in Sec 1049. Precast split-box designs in accordance with ASTM C1786 with or without modification are not an acceptable precast alternative. Approval of a special design for one job does not constitute approval for any other job.

Submittal of special designs is discussed further in EPG 106.16 Special Designs. Special and modified design units, at the discretion of the district, may not be accepted under a QC program.

If reinforcing bars are proposed in lieu of the welded wire fabric listed in AASHTO, it is considered to be a special design.

If end sections are proposed to be constructed other than by the MoDOT Standard Plans for cast-in-place culverts, it is considered to be a special design. Calculations and other proof of equal or better design must be submitted with the request.

REVISION REQUEST 4223

New Test Method

106.3.2.100 TM-100, Procedure to Calculate the Slope Ratio (SR) and Stripping Inflection Point (SIP) using the Hamburg Wheel-Track (HWT) Test

1. Run the HWT test in accordance with AASHTO T 324 at 50 +/- 1 º C for 20,000 passes (regardless of the mix type and contract binder grade).

Record rut depth at each cycle or at regular cycle intervals during the test.

2. Plot the average rut depth versus number of cycles up to the 20,000 passes.

Create a graph using Hamburg Test Data Analysis form that is available at MoDOT’s “Forms for Contractor Use” page on MoDOT’s website.

X-axis: number of wheel passes or cycles.
Y-axis: rut depth in millimeters.
Report the average rut depth at 20,000 passes for all asphalt mixtures:

Binder Contract Grade	Minimum Wheel Passes	Maximum Rut Depth (mm)
58-28H / 64-22	20,000	20,000 4 mm
64-22H / 70-22
64-22V / 76-22

If the average rut depth at 20,000 passes is 4 mm or less, the mixture passes the HWT stripping test and no further analysis is needed. If the rut depth exceeds 4mm, continue with Steps 3 through 5.

3. Identify the two linear portions of the curve.

Determine the two best-fit straight-line sections using a linear regression equation from excel spreadsheet or other graphing tools:

First portion: steady-state rutting region before stripping begins.
Second portion: post-stripping region where rutting increases more rapidly.

4. Calculate the slope of each portion.

Use linear regression for each section:

Slope 1 = slope of the first portion – Creep Slope (M1) from linear regression equation – y = M₁x+ b₁.
Slope 2 = slope of the second portion – Striping Slope (M2) from linear regression equation – y₂ = M₂x + b₂.

5. Calculate the slope ratio.

Slope Ratio = M₂ ÷ M₁

Where:

M₁ = slope of the steady-state rutting portion.
M₂ = slope of the stripping portion.

If slope ration (M₂ / M₁) is less than 2.0 from the two linear equations from the creep slope and stripping slope for 20,000 passes using HWT test, the mixture passes the HWT stripping test and no further analysis is needed. If the slope ration (M₂ / M₁) is 2.0 or greater, continue with Step 6.

6. Calculate the stripping inflection point.

Find the intersection of the two best-fit lines using linear regression equations determined from Steps 3 through 5.

If the first line is:
y = M₁x + b1

and the second line is:
y = M₂x + b2

then:
SIP = (b2 - b1) ÷ (M₁ - M₂)

Where:

b1 = intercept of the first portion.
b2 = intercept of the second portion.
M₁ = slope of the first portion.
M₂ = slope of the second portion.

If the stripping inflection point (SIP) is greater than 15,000 wheel passes, then the mixture passes the HWT stripping test and no further analysis is needed.

7. Interpret the Combined HWT Stripping Results.

A higher SIP generally indicates better resistance to moisture damage.
A lower slope ratio usually indicates less acceleration in rutting after stripping begins.
If no second slope is evident, the mix may not have shown stripping during the test.
If the SIP is 15,000 wheel passes or less, did not pass the 4 mm rut depth in Step 2, and did not pass the slope ratio (SR) of less than 2.0 in Steps 3 through 5, the mixture is unacceptable.

EXAMPLE HWT Report:

Rut depth at 20,000 Passes = 16.3 mm

Slope Ratio = M2/M1 = -0.0014893 / -0.00015636 = 9.52

SIP = = (b2 - b1) ÷ (M₁ - M₂) =

b2 = ((-0.0014893*-17849))+(-13.5956) = 12.9869157
b1 = ((0.00015636*-3067))+(-1.8183) = -1.33874388

SIP = ((12.9869157 – (-1.33874388)) / ((-0.00015636) – (-0.0014893)) = 10,747

With rutting greater than 4 mm, Slope Ratio greater than 2.0, and SIP less than 15,000, this mixture did not pass the HWT stripping criteria and is rutting susceptible.

8. Report the results.

Include the following in the final report:

Contract ID, Project Number, Mix Identification.
Confirm HWT Equipment meets AASHTO T 324.
Confirm Test temperature = 50ºC.
Confirm Number of cycles completed = 20,000 Passes.
Report Total Average Rut Depth at 20,000 Passes.
Establish Rut depth curves.
Provide equations for Creep Slope Best Fit Line and Stripping Slope Best Fit Line using Linear regression methods in excel or other programs.
Report the Slope Ratio.
Report the Stripping Inflection Point.
Report the parameters that the asphalt mixture meets using the table below. When one parameter passes, the other parameters may be omitted.

Parameter	Stripping Criteria	Pass or Fail?
Total Rut Depth	Less Than or Equal to 4 mm
Slope Ratio (SR)	Less Than 2.0
Stripping Inflection Point (SIP)	Greater Than 15,000 Passes

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REVISION REQUEST 4224

This test method establishes the procedures for identifying potential alkali carbonate reactivity (expansion) and acceptance of aggregate used in concrete pavements and masonry. This test method applies to new quarries, new ledges (and combinations of ledges), existing quarries and ledges.

106.3.2.93.1 Means of Evaluating Aggregate Alkali Carbonate Reactivity

1. Chemical Analysis

The chemical analysis of aggregate reactivity is an objective, quantifiable and repeatable test. MoDOT will perform the chemical analysis per the process identified in ASTM C 25 for determining the aggregate composition. The analysis determines the calcium oxide (CaO), magnesium oxide (MgO), and aluminum oxide (Al₂O₃) content of the aggregate. The chemical compositions are then plotted on a chart with the CaO/MgO ratio on the y-axis and Al₂O₃ percentage on the x-axis per Fig. 2 in AASHTO R 80. Aggregates are considered potentially reactive if the Al₂O₃ content is greater than or equal to 1.0% and the CaO/MgO ratio is either greater than or equal to 3.0 or less than or equal to 10.0 (see chart below). See flow charts in 106.3.2.93.2 for approval process.

* MoDOT’s upper and lower limits of potentially reactive (shaded area) aggregates.

2. Petrographic Examination

A petrographic examination is another means of determining alkali carbonate reactivity. The sample aggregate for petrographic analysis will be obtained at the same time as the source sample. MoDOT personnel shall be present at the time of sample. The petrographic sample shall be placed in an approved tamper-evident container (provided by the quarry) for shipment to petrographer. Per ASTM C 295, a petrographic examination is to be performed by a petrographer with at least 5 years of experience in petrographic examinations of concrete aggregate including, but not limited to, identification of minerals in aggregate, classification of rock types, and categorizing physical and chemical properties of rocks and minerals. The petrographer will have completed college level course work in mineralogy, petrography, or optical mineralogy. MoDOT does not accept on-the-job training by a non-degreed petrographer as qualified to perform petrographic examinations. MoDOT may request petrographer’s qualifications in addition to the petrographic report. The procedures in C 295 shall be used to perform the petrographic examination. The petrographic examination report to MoDOT shall include at a minimum:

Quarry name and ledge name; all ledges if used in combination
MoDOT District where quarry resides
Date sample was obtained; date petrographic analysis was completed
Name of petrographer and company/organization affiliated
Lithographic descriptions with photographs of the sample(s) examined
Microphotographs of aggregate indicating carbonate particles and/or other reactive materials
Results of the examination
All conclusions related to the examination

See flow charts in EPG 106.3.2.93.2 for the approval process. See EPG 106.3.2.93.3 for petrographic examination submittals. No direct payment will be made by the Commission for shipping the petrographic analysis sample to petrographer, or for the petrographic analysis performed by the petrographer.

3. Concrete Prism/Beam Test

ASTM C 1105 is yet another means for determining the potential expansion of alkali carbonate reactivity in concrete aggregate. MoDOT will perform this test per C 1105 at its Central Laboratory. Concrete specimen expansion will be measured at 3, 6, 9, and 12 months. The test specimens will be considered alkali carbonate reactive (expansive) if the specimens expand greater than 0.030% at 12 months. See flow chart in EPG 106.3.2.93.2 for the approval process.

106.3.2.93.2 Approval Process for Potential Alkali Carbonate Reactive Aggregate

1. Process for New Ledges and New Quarries The flowchart shown in Figure 1 shows the process for determining alkali carbonate reactivity (expansiveness) in new ledges and quarries. It is important to note TM-93 is only for determining whether or not aggregate is potentially expansive. All other requirements of Sec. 1005 shall be met for the ledge(s) to be approved for use in pavement or masonry concrete.

Should ASTM C 1105 test method need to be performed on the aggregate, the quarry will be notified by District personnel that this test method requires 12 months to complete, and approval of aggregate during those 12 months will be provisionally granted based on physical test results. Final approval will be determined upon completion of ASTM C 1105. Aggregate that fails to meet the expansion limit of 0.030% cannot be approved for use in pavement or masonry concrete. The aggregate however, can be considered for other uses based on meeting required specifications.

Figure 1. Process for determining alkali carbonate reactivity for new ledges and quarries.

2. Process for Existing Ledges and Existing Quarries

The flowchart shown in Figure 2 shows the process for determining alkali carbonate reactivity (expansiveness) in existing ledges and quarries. It is important to note TM-93 is only for determining whether or not aggregate is potentially expansive. All other requirements of Sec. 1005 shall be met before the ledge(s) are approved for use in pavement or masonry concrete.

Should ASTM C 1105 test method need to be performed on the aggregate, the quarry will be notified by District personnel that this test method requires 12 months to complete, and approval of aggregate during those 12 months will be provisionally granted based on physical test results. Final approval will be determined upon completion of ASTM C 1105. Aggregate that fails to meet the expansion limit of 0.030% cannot be approved for use in pavement or masonry concrete. The aggregate however, can be considered for other uses based on meeting required specifications.

Figure 2. Process for determining alkali carbonate reactivity for existing ledges and quarries.

106.3.2.93.3 Submitting Petrographic Examinations Reports to MoDOT

1. Petrographic Examination Reports

Petrographic examination reports can be used in the process to determine the alkali carbonate reactivity (expansiveness) of aggregate. See petrographer requirements in Section 109.3.2.93.1. When a quarry obtains a petrographic examination report, the report shall be submitted to the District Construction and Materials Department of the district the quarry resides. The submittal can be made electronically or can be an original hard copy mailed/delivered to the district. Hard copy reports will be scanned/digitized for easier file storage. Regardless of whether or not the petrographic examination report shows the aggregate is potentially expansive, MoDOT will retain the report. The district will forward the report to Central Office Construction and Materials Division for document retention. This will allow time to prepare for ASTM C 1105 testing if necessary.

All petrographic reports will be digitally stored by Central Office Construction and Materials Division.

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