Category:402 Bituminous Surface Leveling
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402.1 Design of Contract Leveling Course Projects
402.1.1 Plan Preparation
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.
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:
- 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 into future projects.
- Each project should have, as a minimum, the following:
- 1. Location Sketch - with north arrow pointing to the top of the sheet, if possible.
- 2. Length of Project - should include "exceptions".
- 3. Typical Section - should include "estimate factors".
- 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.
- Contract Leveling Course (CLC) Plan Templates are available in ProjectWise.
- 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.
- Districts need to supply at time of submittal conflict of interest documentation (see Submission of Plans and Supporting Documents).
- 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 Work Funded by Maintenance.
402.1.2 Mix and Quantities
Tack quantities are based on tacking the entire roadway surface at an estimated minimum rate of 0.08 gallons/yd2. The asphalt binder for the contract leveling course mixture (surface leveling) should typically be PG 64-22. Asphalt lift thickness and estimate factors used for calculating mix quantities should be shown on the typical section sheets for the project. Minimum thicknesses are 1 in. for Plant Mix Bituminous Surface mixtures, 1 1/2 in. for BP-2 mixtures and 2 in. for BP-1 mixtures. Additional asphalt quantities should be included with single lift overlays to account for surface irregularities. The additional asphalt quantities added should be in accordance with the average rutting depth measurements from the roadway as provided in the following table:
| Average Rut Depth* (inches) |
Additional Asphalt Quantities (Tons per Lane Mile) |
|---|---|
| ≤ 1/16 inch | None Required |
| > 1/16 to 1/8 inch | 16 tons per lane mile |
| > 1/8 to ¼ inch | 32 tons per lane mile |
| > ¼ to 3/8 inch | 48 tons per lane mile |
| > 3/8 to ½ inch | 64 tons per lane mile |
| > ½ inch | Profile mill or additional lifts required |
| * The average rut depths can be estimated by one of the following methods: Method 1 – Field measurements using a 4-ft straight edge across the wheel path. An average of rut depths should be taken that encompass a well representation of the roadway profile (curves, tangents, superelevations, etc…). Field measurements should be taken with the appropriate traffic control in place to provide a safe working environment. | |
The Bituminous 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 Design Exception Information Form should be provided for the State Design Engineer.
| Corridor Designation | Traffic | Recommended Mix and Thickness |
|---|---|---|
| Light Duty | AADT < 1750 | 1 in. Sec 402 Mixture1 |
| Light Duty | 1750 < AADT < 3500 | 1 1/2 in. BP-22 (Sec 401) |
| 1 For structurally sound pavements, 3/4 in. Sec 402 mixture meeting BP-3 requirements may be substituted. | ||
| 2 A 2 in. BP-1 (Sec 401) mixture may be substituted for this application if, in the district's judgment, this substitution is warranted. | ||
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.
402.1.3 Traffic Control, Pavement Marking and Signing
Traffic control plans and job special provisions should be prepared and submitted by the districts. Traffic control plan templates are available in ProjectWise. Sample job special provisions are also available from the Design Division. The quantity of "No Center Line" 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, General (MUTCD Chapter 3A) - Permanent Pavement Markings provide guidance for selection of pavement marking material.
402.2 Construction Inspection for Sec 402
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.
402.2.1 Material (Sec 402.2)
Reclaimed Asphalt Pavement (Sec 402.2.3)
See Reclaimed Asphalt Pavement (RAP) in Plant Inspection.
402.2.2 Composition of Mixture (Sec 402.3)
Gradation of Combined Aggregates (Sec 402.3.1)
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 Standard Specification Section 402.3.1.
Alternate Gradation (Sec 402.3.2)
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.
Reclaimed Asphalt Pavement (Sec 402.3.3)
See Reclaimed Asphalt Pavement (RAP) in Plant Inspection.
402.2.3 Job Mix Formula (Sec 402.4)
The requirements of Standard Specification Section 401.4 apply.
402.2.4 Gradation Control (Sec 402.5)
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 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.
| Property | Tolerance |
|---|---|
| #200 | ±2.0% |
| Binder Content | ±0.5% |
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.
402.2.5 Sample Location (Sec 402.6)
See "Reclaimed Asphalt Pavement (RAP)" and "Sieve Analysis" in Plant Inspection. When sampling for the binder content of the mix, see also "Asphalt Binder Content."
402.2.6 Moisture Content (Sec 402.7)
See Asphalt Binder Content. When sampling for the binder content, also determine the moisture content of the mix.
402.2.7 Contamination (Sec 402.8
See Material Acceptance.
402.2.8 Field Laboratory (Sec 402.9)
See Field Laboratory.
402.2.9 Construction Requirements (Sec 402.10)
Weather Limitations (Sec 402.10.1)
See Weather Conditions. SL mixes shall not be placed if the ambient air temperature or the existing surface temperature is below 50°F.
Bituminous Mixing Plants (Sec 402.10.2)
Subgrade Preparation (Sec 402.10.3) 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.
Hauling Equipment (Sec 402.10.4)
See Haul Trucks.
Spreading (Sec 402.10.5)
See Spreading and Hand Spreading in Paving Operations.
- Irregularities (Sec 402.10.5.1)
See Spreading in Paving Operations.
Joints (Sec 402.10.6)
See Transverse Joints and Longitudinal Joints in Paving Operations.
Compaction (Sec 402.10.7)
See Rollers in Paving Equipment and 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.
Surface Condition (Sec 402.10.8)
See Material Acceptance.
402.2.10 Method of Measurement
The total tonnage accepted will be measured to the nearest 0.1 ton.
402.2.11 Basis of Payment
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).
402.3 Materials Inspection for Sec 402
402.3.1 Scope
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 EPG 1001 General Requirements for Material. Plant calibrations, if requested, shall be performed in accordance with EPG 106.4 Plant Inspections.
402.3.2 Procedure
Mix design procedures are identical to those shown in 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 EPG 403.3 Laboratory Procedures for Sec 403.
402.4 Laboratory Procedures for Sec 402
This establishes procedures for Laboratory testing and reporting of plant mix bituminous surface leveling trial mixtures.
402.4.1 Procedure
Trial mixture test results and calculations required for plant mix bituminous surface leveling will be determined as shown in Laboratory Procedures for Sec 403. No field compacted density samples are required.
402.4.2 Sample Record
The sample record shall be completed in AASHTOWARE Project (AWP), as described in AWP MA Sample Record, General. Test results shall be reported on the appropriate templates under the Tests tab.
402.5 Maintenance Operations Following Contract Level Course Projects
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.
Work items to be completed by MoDOT:
- 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.
- 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.
- 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 Temporary Raised Pavement Markers (TRPMs) and 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.
- 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.