Selection Procedures for Pavement Warranties
"How to establish criteria and how to select projects."
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The Federal Highway Administration (FHWA) intends to continue supporting and encouraging the use of pavement warranties throughout the United States. This is the second in a series of documents intended to provide guidance on the use of pavement warranties. It is arranged to address various highpoints that should be considered in all warranty programs, independent of the source of funding or system. The first document was intended to provide agencies the information to gain an understanding of what warranties are and insight on why they should be used. This second document will discuss the selection procedures for pavement warranties and will include specification development, bonding or guarantee issues, project selection, acceptance, and verification procedures for warranty projects. In addition, warranty experiences from various states will also be presented.
Implementing a Warranty Program
While there are several choices in the types of warranties that can be used for pavements, the most benefit can be gained through the use of long-term performance warranties. Performance type warranty specifications have been documented to reduce the life cycle costs of the facility by improving the performance of the pavements.[5,6,10,11] To continue the trend toward improved pavement performance it is important to examine and to implement the best practices and lessons learned by agencies in the United States and abroad. The successful use of pavement warranties is dependent upon the understanding of the contracting as well as the support of the parties involved.
There are a number of issues that need to be considered when implementing a warranty program. While there are many potential benefits such as improved performance, there are also adjustments that will need to be made within the highway construction industry, the agency, and in the bonding requirements. The agency and contractors risk also has to be minimized to achieve a good warranty program.
Pavement warranty projects require specifications that will be substantially different than the specifications most agencies use on most other types of projects. This section will identify issues an agency needs to consider in developing specifications for projects pavement warranties.
Independent of the type of warranty specification is the need for buy-in by both agency and industry representatives. Bringing the representatives together develops a better understanding of the specifications and the meaning behind the specifications. Discussions with the bonding companies upfront may provide critical information to what the bond actually covers, the responsibilities of all parties, and the remediation process. Industry and agency concerns need to be discussed fully.
The agency needs to provide the design year traffic or Equivalent Single Axle Loads (ESALs) for all warranty projects. The agency needs to identify the number of Class 5 and above vehicles for a traffic level threshold. The contractor needs some maximum volumes to establish the risk. It is recommended that if the number of Class 5 truck ESALs exceeds 150% of the design levels, the contractor should be released from the warranty. In order to obtain this type of information accurately, it may be necessary to install Automatic Vehicle Classification (AVC) devices in the vicinity of the warranty project, or rely on a nearby weigh station, for the warranty period. Holding the contractor to unlimited increases of traffic is beyond the contractor's control and is not recommended.
Key elements that need to be discussed include the utilization of the agency's existing quality assurance procedures used in other non-warranty contracts. Acceptance of materials and construction activities is dependent on the quality control/quality assurance (QC/QA) procedures, and acceptance of the warranty activities is dependent on the field measurement and evaluation procedures to be utilized for the warranty projects. If an agency does not have QC/QA processes in place for a particular warranted program, it is not recommended that warranties be considered for use by the agency. The warranty specifications should include areas as described below.
- Materials and Workmanship Warranties
Materials and workmanship type warranties require the contractor to correct defects in the pavement caused by elements within their control and assume no contractor responsibility for the design. Materials and workmanship warranties follow an agency's current standard specifications for the specific treatment. Acceptance of these warranted projects is in accordance with an agency's normal practices. The only difference is the contractor carries the additional risk of premature failures and subsequent repairs beyond the normal bonding contract requirements of the agency.
- Short-Term and Long-Term Performance Warranties
The development of specifications for short-term and long-term performance warranties is dependent on the agency's contracting procedures with the differences being primarily in length of warranty, bonding/guarantees, roadway design requirements, magnitude of the project, risk, and acceptance criteria. The core elements for both types of performance warranties that should be included in the specifications are:
- Warranty Bond/Guarantee Requirements
- Conflict Resolution Team
- Permit Requirements
- Pavement Distress Indicators, Thresholds, and Remedial Action
- Elective/Preventive Actions
- Agency Maintenance Responsibilities
- Method of Measurement
- Basis of Payment
- Quality Control Plans
- Verification and Evaluation
- Final Warranty Acceptance
The specification development process is the same for both Hot Mix Asphalt (HMA) and Portland Cement Concrete (PCC) pavements. The differences are which distresses are warranted and their respective remediation.
- Description: The specification needs to establish what work is being warranted. Mainline pavement is typically targeted as the warranted item, but if auxiliary lanes, shoulders, or other work, such as subgrade, base or roadway hardware items, are included it needs to be clearly spelled out. In addition, the date or time when the construction activities end and the warranty period begins should be clearly defined. This is very critical when considering a multi-year contract or a multi-phased construction as part of the warranty project. Typically, the warranty begins when the construction project is completed and opened up to unrestricted traffic regardless of the phasing or the length of the construction time of the project.
Short-term warranties: it is recommended that the agency establish the minimum materials requirements for HMA pavements regarding binders and aggregates; for PCC pavements the minimum requirements for aggregates and other pavement items such as dowel bars, etc. when required by the design.
Long-term warranties: the contractor is responsible for all quality control activities and should be responsible for the minimum materials requirements as applicable.
- Warranty Bond/Guarantee Requirements: The bonding requirements to assure the resolution of any noted deficiencies during the warranty period are defined as the warranty bond. Warranty bonds can be developed with various elements such as constant level, straight-line depreciation, stepped depreciation, or a variable depreciation over the length of the warranty. Determining what is included in the warranty bond is also critical.
Short-term warranties: agency bonding requirements for initial construction activities are typically the same as for non-warranty projects. For full depth HMA, the warranty bond typically includes only the replacing of the surface materials. If the warranty includes the subgrade, the warranty bond may include all the pavement materials. The warranty bond for PCC projects generally includes the placement of HMA or PCC overlays.
Long-term warranties: bonding is more difficult but generally includes all the paving materials. A bonding/guarantee program in conjunction with pre-qualification, best value bidding is recommended in lieu of straight bonding. The bonding/guarantee issue is very critical to the agency's and industry warranty program. Discussions with bonding representatives during the development of the warranty specifications are recommended. Warranty bonding is further discussed in the next section of this guidance document.
- Conflict Resolution Team: Warranty specifications define what the agency is requiring and the method of payment for such activities. Disputes on warranty projects are generally fewer than on non-warranty projects due to collaborative attitudes between the parties, but questions and/or conflicts still occur that need an alternate means of resolution. Projects with warranty specifications generally are not handled as typical agency projects due to the increased responsibilities of the contractor in the project, and therefore the specification needs to include provisions to address disputes. A conflict resolution team should be assembled to address these disputes and consists of two representatives selected by the agency, two representatives selected by the contractor, and a fifth independent representative jointly agreed to by both parties. All members of the resolution team need to be knowledgeable with general materials, construction requirements and programs, as well as the terms and conditions of the warranty specifications. The conflict resolution team members need to be identified in writing at the pre-construction meeting.
The scope of the conflict resolution team responsibilities needs to be included in the warranty specifications and should address all issues concerning the warranted pavement relative to: material selection, contractors construction activities and quality control plan, warranted pavement distress rate, measurement and calculation of pavement distresses, and evaluation and remediation of pavement distresses. Provisions should also be provided to address impasses within the team. Team decisions are based on consensus or majority votes with the recommendations submitted to the head of the agency for the final decision, when required by state laws regarding dispute resolution. Independent of the duties of the team, the specifications need to be clear that the team's function is to review the warranted items during the warranty period as well as the construction activities.
Caution is needed when establishing conflict resolution teams, in particular to the legality of the team. Agency laws and regulations need to be evaluated and complied with during the development of the specifications. Some agencies require all final decisions to be made by the head of the public agency, or its public designee, when public monies are involved.
- Permit Requirements: During the warranty period remedial work may be performed at no cost to the agency and should be based on the results of pavement distress surveys. The contractor and the agency should make a joint decision on the remedial work to be performed, and the specifications and materials to be used. The warranty specifications need to include procedures for remedial actions that address the contractor's responsibilities and the agency's needs. Depending on agency requirements, general roadway permits may be necessary to allow the contractor to work on the roadway after the initial construction activities are completed. For example, if the contractor proposes to conduct remedial work in advance of the pavement distress surveys, work permits may need to be obtained from the agency. The agency requirements for roadway permits should include any specific additional details regarding lane closures, testing protocols, and traffic control requirements. In addition, prior to proceeding with any remedial actions or monitoring activities, the contractor may also need to obtain other permits from the relevant agencies.
The following are examples of these additional requirements:
- Lane Closure Periods. Lane closures are the same as lane rentals. A minimum of two mainline lanes in each direction shall be open to unrestricted traffic during any closure period when warranty work is performed. Costs for closure periods may be applied using the following closure period rates:
Peak Hour: $2,000.00/lane/hour
Non - Peak Hour: $ 400.00/lane/hour
Weekday and weekend peak hours are from 6:00 AM to 8:00 PM, and non-peak hours are from 8:00 PM to 6:00 AM.
- Testing Protocols. During the warranty period the contractor may monitor the warranted pavement using nondestructive procedures. All proposed remedial action(s) should be coordinated with the agency.
- Traffic Control. Traffic control in accordance with agency requirements is required to ensure the safety of the traveling public. Agency advance signing and lane closure procedures shall be utilized and coordinated with the agency prior to initiating the activities.
- Pavement Evaluation. The contractor, without prior consent of the agency, may not perform coring, milling, grinding, or other destructive procedures to evaluate the pavement. If the contractor elects to conduct any independent testing, both destructive and non-destructive, the equipment shall be calibrated and correlated with the agency's equipment. The contractor shall not be responsible for damages to the pavement as a result of coring, milling or other destructive procedures conducted by the agency.
- Remedial Work. The contractor should have the first option to perform remedial work. If, in the opinion of the agency, the problem requires immediate attention for the safety of the traveling public and the contractor cannot perform the remedial work within twenty-four (24) hours, the agency has the option to have the remedial work performed by other forces. The contractor is responsible to pay for all the direct costs incurred. Remedial work performed by other forces shall not alter the requirements, responsibilities, or obligations of the warranty.
Pavement Distress Indicators, Thresholds, and Remedial Action: When developing a warranty specification, the agency needs to consider several factors to establish pavement distresses, thresholds, and remedial actions. The agency first needs to consider the length of the warranty period, the type of project being considered (i.e., new construction, rehabilitation, resurface, or preventive maintenance), the highway system being considered (i.e., Interstate, two or four lane high volume facility, etc.), and the condition of the pavement management data for all the above considerations. Utilizing warranties does not change the agency's responsibility to the public to maintain a high level of pavement condition that is safe to use and to minimize any future delays or congestion due to the premature pavement deterioration. Warranty criteria should be based on the properties routinely collected by the agency as part of their Pavement Management System (PMS) and should be measured objectively using current technology to the maximum extent possible. Additionally, the frequency of the PMS evaluations needs to be factored into the process, as this will be utilized in the warranty pavement evaluations. The use of subjective distress evaluations should be minimized. It is recommended that warranties can be used for mainline, auxiliary lanes, and shoulders. Ramps, turn lanes, and other miscellaneous pavement elements are considered incidental to the mainline pavement and are generally not included in the warranted pavement.
Analyzing the PMS project data based on age and highway system will establish a baseline for determining the thresholds. Typically, PMS data systems are based on 1.0 mile (1.6 km) segments, which is not appropriate for warranty projects. It is recommended that a further reduction of the segments to 0.1 mile (0.16 km) or less will provide the degree of pavement variations to objectively evaluate the condition of the pavement over the warranty period.
For HMA warranty projects, it is recommended that the pavement condition indicators be friction, International Roughness Index (IRI), longitudinal cracking, rutting, and transverse cracking. For PCC warranty projects, it is recommended that the pavement condition indicators be friction, IRI, joint sealant condition, longitudinal cracking, scaling, and transverse cracking. These pavement condition indicators are recommended based on the assumption that the operations are under the control of the contractor.
Depending upon the completeness of the agency's PMS data, additional indicators may be included. It is recommended that only those objective indicators that directly affect the safety of the facility and the performance of the pavement be utilized. For example, segregation and block cracking of HMA pavements does affect the performance of the pavement but it is a subjective evaluation and is already included in the rideability, or IRI, of the facility as well as in longitudinal cracking indicators.
Establishing the threshold criteria for the pavement distresses is dependent on the availability of the data and should be realistic and attainable based on historical PMS data. Setting extreme limits may cause the contracting industry to unbalance the bids to account for unreasonable quality limits for the project. For example, the local rates of rutting in HMA pavements over time are typically known by the agency and there should be a good understanding of the rutting issues. To determine the warranty distress indicators, the agency can use the average rutting experienced on different types of pavements based on age and highway system. Then by calculating the standard deviation of the segments the agency can establish the initial thresholds. The warranty distress indicators for rutting should be two standard deviations from the mean of the segments. The same process can be repeated for smoothness and friction. After the initial thresholds are established, further evaluation of the PMS database should be made to identify outliers and determine their effects on the results.
Distresses such as transverse or longitudinal cracking on HMA and joint sealing on PCC pavements probably will not have sufficient data to evaluate the pavement performance. In that instance, best engineering judgment has to be utilized to determine what is not acceptable.
Remedial actions for addressing pavement distress should be acceptable to the agency. The agency will be assuming liability for the roadway at some point following the initial construction activities and warranty period, and agency assurance of continued pavement performance is needed.
Using objective methods to establish the pavement warranty distress indicators provides a better understanding of the intent of the warranty specifications to contracting, bonding and industry representatives.
- Elective/Preventive Actions: Elective/preventive actions should be the contractor's option and should have agency concurrence. Maintenance operations (by the contractor) to keep the pavement within the limits of the distress indicators are the responsibility and the judgment of the contractor. Typical preventive maintenance operations for HMA pavements could be crack sealing, patching, or surface replacement or treatments; for PCC pavements, it could include crack sealing, patching, or joint material replacement. For elective/preventive actions closure periods for assessments are not normally charged to the contractor.
- Agency Maintenance Responsibilities: The warranty specifications need to clearly state the roles and the responsibilities of both the contractor and the agency regarding maintenance responsibilities. The contractor is responsible for the performance of the pavement for the warranty period but generally not the entire project. The agency should assume normal routine maintenance responsibilities during the warranty period such as snow plowing and applying de-icing chemicals, repairs to safety appurtenances, pavement markings, mowing, and sign maintenance. The warranty specifications need to clearly state that during the warranty period, the agency will not perform routine pavement maintenance activities. Contractor and agency responsibilities will vary by the type of warranty. Long-term or pavement performance contracts especially need clarity regarding the pavement maintenance responsibilities and the safety related roadway items such as pavement marking, roadside signs and guardrails, etc.
- Method of Measurement: The agency needs to consider various methods to address the measurement and payment for the warranted pavement. Short or long-term risk for pavement performance is the contractor's responsibility but it is generally included in the construction costs. Agencies need to consider if the cost for the pavement warranty itself will be included in the cost of the bid item (either by the unit measurement or lump sum value) or as a separate lump sum pay item. Warranty expenses generally include the costs for additional bonding for the specified warranty period, additional testing of materials, anticipated preventive maintenance activities, and possible remediation activities. To facilitate the documentation of the costs of warranties, it is recommended that agencies utilize their standard measurement procedures for the pavement items for the warranted HMA or PCC pavements and use a separate lump sum pay item for the pavement warranty cost.
Basis of Payment: The basis of payment for construction activities is dependent upon the method of measurement for the warranted pavement. It is recommended that the following be made clear and be included in the cost of the warranted pavement: Payment will be full compensation for furnishing, preparing, hauling, mixing and placing all materials. The warranty bond, warranty work, mixture designs, quality control plan and all testing, recordkeeping, sampling and traffic control for remedial or elective/preventive actions are included in the pavement warranty cost.
In the case of HMA warranted pavement, construction of the mixtures should be included as well as the liquid binder. For PCC warranted pavement, finishing and curing of the concrete and providing and placing of the pavement joints, if required by the agency, should be included.
Typically warranty projects should not include price adjustments for various pavement elements such as the initial smoothness of the pavement or degrees of compliance with the targeted material elements. Price adjustments for material cost during construction (i.e., liquid binders, fuel, cement, etc.) are an agency decision. Some agencies do include incentive payment procedures for significant compliance with the warranty elements. Including incentives as part of the construction project is basically paying for the incentives once for the construction work and another for the same work but as part of the warranty and as such, it is not recommended.
The initial warranty specifications need to include the details in the contract if incentive payments will be made during the warranty period. For long-term performance warranties, increased payment for construction activities or the warranty are not recommended.
- Quality Control Plans: The contractor's quality control plan (QCP) is a critical element to the success of a pavement warranty program. The contractor's QCP should be provided to the agency, maintained in a timely manner, and followed to assure the agency that all materials furnished and placed are in accordance with the warranty. The QCP should not be approved by the agency, as this assumes ownership and responsibility of the contents. The agency may disagree with elements in the QCP and has the option to refer their comments to the conflict resolution team for disposition. The QCP should note as a minimum the following:
- The procedures to be used for design, sampling and testing of all materials, and methods and frequency of calibration of all testing equipment.
- Contract specific details for placement activities and anticipated testing frequencies.
- Names and qualifications of the contractor's personnel who will be conducting sampling and testing of materials.
- Mixture design methodologies to be used on HMA or PCC projects.
- List of all materials proposed to be used in HMA or PCC projects, including specific properties of each. The contractor should also supply sufficient documentation to demonstrate that all materials meet standard quality requirements for the application. The contractor should be responsible for certifying to the agency that all products used during HMA or PCC production meet the quality requirements as established by the contractor in the QCP.
- Mixing plant requirements, including the calibration of all meters, scales and other measuring or recording devices.
- Proposed sampling procedures and size of samples necessary for testing and controlling HMA or PCC mixtures. The test methods and minimum frequencies of the quality control tests should be stated.
- Quality control charting needs to include the limits for quality control activities to meet the agency established thresholds.
- Compliance with the agency's independent assurance program procedures.
- Procedures for documenting all material certifications, production test reports, quality control charts, test equipment certifications and calibrations, and any other material and/or design or production related records. Should be maintained for a period that includes the terms of the warranty.
- Records, either electronic or paper, should be maintained in a readily accessible location for access by the agency at any time. Upon completion of the placement and the opening of the warranted HMA or PCC pavements to traffic, the contractor is responsible for providing copies of all QC records to the agency.
- Verification and Evaluation: The agency is responsible for routine evaluations of the warranted pavement during the warranty period. The agency needs to clearly indicate how the pavement condition will be verified for each of the warranted pavement indicators and who will be conducting the evaluation during the warranty period. The agency will evaluate the findings from the field verification and will report the conditions to the contractor during (annually, biannually, etc.), and at the end of, the warranty period. During the warranty period, the contractor has the right, with the agency concurrence, to independently review the condition of the warranted pavements for their use and information.
To minimize discussions regarding the accuracy of the evaluations, the agency needs to make the evaluation process as objective as possible. The agency's Highway Performance Monitoring System (HPMS) and PMS programs are objective and repeatable and are recommended to address the warranted pavement distresses. Pavement indicators such as friction that are not part of the HPMS program can still be objectively evaluated by utilizing the agency's existing pavement friction evaluation program.
During the course of the evaluations the agency should also note any general pavement distresses. Most of the pavement indicators are not reviewed continuously throughout the warranted project and are typically only in the driving lane. If any values exceed the thresholds more detailed testing and inspection may be conducted to determine the extent and limits of the deficiency. Any area outside the tested lanes, or sample sections observed, that shows deficiencies may also be tested and used to determine the pavement warranty acceptability and to verify the uniformity of the quality of the project.
Roughness measurements may be used to monitor the performance of the pavement in lieu of distress surveys. Pavement distresses such as various types of cracking, corrugations, or distortions are not measured or rated directly, but they may affect the ride measurement and may need correction to provide satisfactory warranty values. The ride measurement does not indicate why the ride may be unsatisfactory. Detailed inspection and testing to examine individual distress mechanisms will be required to determine the remediation to provide the quality necessary for the expected service life of the pavement.
- Final Warranty Acceptance: The agency needs to specify what will constitute final warranty acceptance. As a minimum, this section in the specifications needs to consist of a field evaluation that addresses each of the warranted pavement indicators and written documentation that transfers pavement maintenance responsibilities back to the agency.
Bonding Requirements or Guarantee Issues
The purpose of bonding or guarantee is to provide the agency the assurance that any noted deficiencies will be resolved during the warranty period. Most agencies currently require a construction bond that covers the actual construction period, which typically includes one additional year beyond construction for general workmanship issues.
Warranty bonds have been developed using various methods to reduce the outstanding bonding requirements for contractors that includes a constant level, straight-line deprecation stepped depreciation, or a variable depreciation over the length of the warranty. For pavement warranties, the Florida DOT (FDOT) is in the process of moving away from bonding altogether and replacing it with a contractors pre-qualification program that is heavily weighted towards performance. The FDOT intends to limit the bidders on warranted pavement performance projects to only those that have a high performance rating.
Materials and workmanship warranties typically utilize the constant level bonding method for the warranty period. The bonding is typically just an extension of the initial construction bond.
Performance warranties are dependent on which type of warranty is being developed since short-term and long-term warranties have significantly different requirements.
Short-term warranties: typically utilize the constant level or straight-line depreciation methods. With the warranty periods less than 10 years, the agency's options are generally limited.
Long-term warranties: agencies have more options to address the contractor's responsibilities and liabilities. Discussions with the local bonding representatives early in the development of the warranty programs are critical to establish knowledge of the programs. Experience has shown that in agencies with multiple warranty projects, the bonding costs have been reduced over time. Initial resistance by bonding representatives can be addressed with clarity in the warranty specifications, knowledge of the contractors completing the warranty work, and knowledge of the agency's warranty program.
There are several bonding requirements related to the implementation of warranties that include the length of the warranty period, the mitigation plan for observed distresses, and the timeframe for repairs, in addition to the contractor's experience and qualifications to perform the work. Various agencies have utilized alternate methods to determine the value of the pavement warranty bond and accompanying payment procedures. Regardless of how the agency determines the program, the bonding requirements need to be clearly detailed in the specifications. The following is a sampling of methods for determining the bonding level for warranted projects.
|State||Product||Payment Methods / Bond|
|Alabama||Hot Mix Asphalt||Bond for specified % of contract amount; also retainage of 10% of contract paid over 8 years|
|California||Rubberized Hot Mix Asphalt||Bond for 10% of contract amount; also retainage of 10% of contract paid over 5 years|
|Colorado||Hot Mix Asphalt||Bond to cover cost of 2.0 inch (50 mm) overlay, restriping, traffic control, rounded up to nearest $25,000|
|Florida||Hot Mix Asphalt||Bond to cover cost of 1.0 inch (25 mm) overlay|
|Indiana||Hot Mix Asphalt||Bond to cover 1.0 inch (25 mm) removal and overlay|
|Portland Cement||Bond is based on 30 % of the warranted pavement item|
|Microsurfacing||Bond for 100% of contract amount for microsurfacing work|
|Michigan||Hot Mix Asphalt||Bond for 10% of contract amount|
|Hot Mix Asphalt Overlay||Bond for 100% of contract amount|
|Chip Seal / Microsurfacing / Crack Treatment||Bond for 100% of contract amount|
|Ohio||Hot Mix Asphalt||Bond for cost of removal and overlay at five years considering inflation. Includes traffic control, markings, etc.|
|Microsurfacing||Bond for 75% of contract amount|
|Wisconsin||Hot Mix Asphalt||Bond to cover cost of replacement overlay, re-grade shoulders, rounded to next $100,000|
As the lessons learned from our European counterparts indicate, not all projects lend themselves to the use of pavement performance warranties. There are other contracting mechanisms that may be more appropriate to consider, however, this section describes how to select the type of warranty to meet project conditions. Warranties are just one innovative contracting alternative to select from to meet project and agency requirements.
Project selection for warranties is just as critical as the development of the specifications and depending on the type of warranty, only certain types of projects will be good candidates for warranties. Key points in the selection process include:
Material and workmanship warranties are generally limited only to preventive maintenance surface treatments, making project selection generally easier. Exceptions to this are microsurfacing. Care has to be taken not to select a facility that has excessive surface deteriorations that are beyond the ability of the microsurfacing to address in one application, or in the case of minor rutting, two applications. Material and workmanship warranties (3 years) have also been applied successfully to HMA resurfacing/rehabilitation projects.
Short-term performance warranties are very adaptable to rehabilitation or resurface type projects, and they are also very applicable to new construction. For rehabilitation type projects, the contractor is only responsible for new overlay and cannot be responsible for the roadways subbase. New construction takes into account the entire roadway pavement and shoulders and typically includes the subgrade.
Long-term performance warranties are typically limited to major new construction projects that are significant in nature and will include the pavement, shoulder, and subgrades, and may also include other roadway items as a complete package.
In selecting projects, the PMS data needs to be evaluated to consider any particular project. For example, if PMS data shows a particular project has a high degree of surface defects, it is normally not a good project for a preventive maintenance single overlay, since more work is needed to rehabilitate the facility. The same holds true with warranties, since the contractor cannot be held responsible for elements of the pavement that were not under their control. This does not mean that only very good projects can be selected for warranties, but it should rule out very poor projects if minor resurfacing is proposed. Coordinating the selection of projects with the PMS program is recommended, in consideration of the type of project (rehabilitation, reconstruction, etc.).
Acceptance Procedures for Warranty Projects:
Acceptance procedures for warranty projects have to incorporate not only the construction activities, but also the verification process. An agency warranty verification process differs depending upon the type of warranties.
Materials and workmanship warranties, acceptance of the construction activities is in accordance with agency standard specifications. The agency is also responsible for reviewing the completed project following the completion of the warranty period to document the condition of the pavement. It is recommended that the agency then prepare documentation that formally releases the contractor from further responsibilities under the contract.
Short-term performance warranties, acceptance of the roadway and other elements of the project are important to ensure that the basic scope of the work was completed in accordance with the plans. Material acceptance of the pavement items is through the verification process. The agency is responsible for reviewing the project during and following the completion of the warranty period to document the condition of the pavement. It is recommended that the agency then prepare documentation that formally releases the contractor from further responsibilities under the contract. Verification of the warranty's pavement condition should be tied to the same PMS program to objectively rate the condition of the pavement. Depending on the length of the warranty, the pavement may be reviewed annually or biannually up to the end of the warranty period when a final condition survey is completed. The pavement ratings need to document each of the warranted distresses throughout the life of the warranty. If any distress exceeds the limits as stated in the specifications, the contractor is responsible for providing a remedy to bring the pavement back into acceptable levels.
Long-term performance warranties are similar to short-term warranties in that the initial construction activities have to be reviewed and the pavement condition is verified over the life of the warranty period. The pavement condition verification reviews by the agency are less frequent than in the field evaluation. It is recommended that an initial, or baseline, evaluation be completed following construction and intermediate evaluations be completed during the warranty period. A final evaluation is completed following the completion of the warranty period.
For warranted HMA pavements distress indicators can use PMS data to determine threshold values for the following recommended performance indicators:
|Pavement Performance Indicators||Evaluation Section||Threshold Values||Notes|
|Friction Number||Three Consecutive Sites||< 25|| |
|Entire Contract per lane||< 35 Average of all tests|
|International Roughness Index (IRI)||100 m|
|Longitudinal Cracking||100 m|
|Rut Depth||100 m|
|Transverse Cracking||100 m|
For warranted PCC pavements distress indicators can use PMS data to determine threshold values for the following recommended performance indicators:
|Pavement Performance Indicators||Evaluation Section||Threshold Values||Notes|
|Friction Number||Three Consecutive Sites||< 25|| |
|Entire Contract per lane||< 35 Average of all tests|
|International Roughness Index (IRI)||100 m|
|Joint Sealant Condition||150 m|
|Beginning at each Reference Marker||4.0 m|
|Longitudinal Cracking||100 m|
|Beginning at each Reference Marker||20 m2|
|Transverse Cracking||100 m|
The World Bank provides examples of the service level criteria for pavements, shoulders, and right-of-way as follows:
|Item||Service quality||Measurement/Detection||Time allowed for repairs or Tolerance permitted|
|Pavement width||Pavement width must be at least as wide as specified in the contract.||Manual measurement using a metallic measuring tape.||No tolerance allowed.|
|Potholes||No potholes allowed.||Visual inspection.||Potholes must be repaired within three (3) days after detection.|
|Patching||Patches (i) shall be square or rectangular, (ii) shall be level with surrounding pavement, (iii) shall be made using materials similar to those used for the surrounding pavement, and (iv) shall not have cracks wider than three (3) mm.|
- Visual inspection (for detection of shape and material used)
- Ruler (to check if patch is level with surrounding pavement)
- Small transparent ruler (for cracks)
|Non-complying patches must be repaired within three (3) days after detection.|
|Cracking in pavement|
(a crack is a linear opening in pavement with a width of more than 3 mm.)
|There shall not be cracks more than 3 mm wide.|
For any 50m section of the pavement, the cracked area cannot be more than ten (10) percent of the pavement surface.
|Crack widths measured with small transparent ruler.|
For isolated cracks, the "cracked area" includes 0,5 m on each side of the crack, multiplied by the length of the crack plus 0,5 m at each end.
For multiple cracks and cracks crossing each other, the "cracked area" is equivalent to a square area, parallel to the lanes, which fully encloses the cracks, and where the closest crack is at least 0.25 m away from the sides of the square.
|Cracks more than 3 mm wide must be sealed within seven (7) days after detection.|
|Cleanliness of the pavement surface and shoulders.||The road surface must always be clean and free of soil, debris, trash and other objects.||Visual inspection||Dirt, debris and obstacles must be removed:|
- within 1 (one) hour if they pose a danger to traffic safety
- within 36 hours if they do not pose any danger to traffic safety.
|Pavement roughness||Average value for section must be below the threshold value given below (in IRI average)|
Section 1: .......... IRI
Section 2: .......... IRI
Section 3: .......... IRI
|Measured with calibrated equipment (Bump Integrator).||No tolerance allowed.|
|Deflection||Average of section must be below the threshold values indicated for each road section.||Measured with Benkelman beam every 50 meters. Threshold value is average for sections of .......... meters.||No tolerance allowed.|
|Rutting||There shall not be ruts deeper than 15 mm.|
Rutting of more than ten (10) mm shall not be present in more than 5 percent of any of the road sections defined in the contract.
|Measured with 2 rulers (horizontal ruler of three 3 m length placed perpendicularly across lane; rut depth measured as space between horizontal ruler and lowest point of rut, using a small ruler with scale in mm)||Rutting above threshold value must be eliminated within fifteen (15) days.|
|Raveling||Raveled areas must not exist.||Visual inspection.||Raveled areas must be sealed within thirty (30) days after their detection.|
|Loose Pavement edges (loose)||There shall not be loose pavement edges, or pieces of pavement breaking off at the edges.||Visual inspection||Repairs must be completed within seven (7) days after the detection of the defect.|
|Height of shoulders vs. height of pavement||Difference in height at edge of pavement shall not be more than 15 mm.||Measured with ruler, with scale in mm.||Repairs must be completed within seven (7) days after the detection of the defect.|
|Paved shoulders||Must always be|
- sealed to avoid water penetration
- without deformations and erosions
- free of potholes and erosions
|Visual inspection||Repairs must be completed within seven (7) days after the detection of the defect.|
|Right-of-way (outside pavement and shoulders).||Height of vegetation (except trees) must be:|
- less than 20 cm on slopes towards the road
- less than 1.0 m otherwise
- must not disturb drainage
|Visual inspection. Measurement with ruler.||Vegetation exceeding the threshold height must be cut back within seven (7) days after detection.|
|Trash, debris, etc.||Visual inspection.||Trash, debris and other objects must be removed within seven (7) days after detection.|
Agencies need to evaluate the data collected from the warranty projects to determine the effectiveness of the warranty programs. The data can also be utilized in the evaluation and establishment of subsequent warranty project thresholds.
Reports of warranty experiences throughout the country have produced mixed results on the use of pavement warranties and the type of the warranty. The Colorado DOT reported that the material and workmanship warranty program was not successful due to the lack of contractual controls in the specifications. The Michigan DOT, which utilizes material and workmanship warranties for a significant portion of their warranty program, also reports very little change in the quality of the initial construction by the contractors. If developed correctly, individual preventive maintenance programs utilizing material and workmanship warranties such as chip seals, etc. can benefit from the warranties due to the emphasis on the operations.
The Wisconsin and the Indiana DOT's have reported successes with short-term warranties in terms of pavement performance and cost effectiveness. Wisconsin utilizes warranties on all types of roadways, including entire pavement replacements. They found that when the contractor is responsible for the subgrade as well as the pavement structure, more attention was focused on all the pavement layers. The Indiana DOT reported the use of warranties on high volume Interstate utilizing single lay (surface course) preventive maintenance type projects, rehabilitation of existing roadways, and new full depth pavements. Data from Indiana shows that the HMA warranty program extends the life of the pavement an additional nine years when considering rutting and smoothness elements.
Long-term performance warranties in the United States are limited and benefits are still being evaluated. European experiences in long-term pavement warranties have shown positive results.
Referenced materials in this guidance information include the following documents: