Various maintenance and rehabilitation options are employed by highway agencies to restore pavement condition and extend pavement life. For specific climate conditions and traffic levels, the performance of the restored pavement will depend not only on the type of maintenance or rehabilitation option, but also on the existing-pavement condition when these measures are applied. However, these relationships are not well documented. Without this information, the selection of appropriate maintenance or rehabilitation options that will ensure long-term performance is a difficult task. The data available from the Long Term Pavement Performance (LTPP) studies are expected to provide such information.
Research is needed to identify the existing-pavement conditions that influence the effectiveness of the different maintenance and rehabilitation options and to determine the relative performance of these options. The findings of this research will provide guidance for identifying appropriate maintenance and rehabilitation strategies of pavements.
The objectives of this research are (1) to identify, based on the data available from the LTPP studies, the pre-maintenance and pre-rehabilitation conditions that influence the performance (as measured by distress) of each maintenance or rehabilitation option and (2) to determine, based on LTPP data, the relative performance of the different maintenance and rehabilitation options. The research shall be limited to using the data available in the LTPP Information Management System (IMS) database classified as "Level E". It will deal with rehabilitation of flexible and rigid pavements and maintenance of flexible pavements and will give special consideration to the existing-pavement condition prior to the application of the maintenance or rehabilitation option; it will not address maintenance of rigid pavements.
Accomplishing these objectives will require at least the following tasks.
Phase I: (1) Collect and review reports relative to the LTPP studies on maintenance of flexible pavements and rehabilitation of flexible and rigid pavements to obtain the information needed to accomplish the project objectives. From the data elements available in the LTPP database, identify the elements needed to conduct this research and determine the extent of availability for each. Acquire the needed data and develop a database that includes the data proposed for use in the project. (2) Based on the information obtained in Task 1, refine the data analysis plan presented in the proposal for determining the relative performance of the different maintenance and rehabilitation options. The analysis plan shall address the performance of the pavement sections included in the General Pavement Studies (GPS) and the Specific Pavement Studies (SPS) experiments dealing with maintenance of flexible pavements (SPS-3), rehabilitation of flexible pavements (GPS-6B and SPS-5), and rehabilitation of rigid pavements (GPS-7B and SPS-6). The plan shall also address maintenance and rehabilitation activities as well as pavement type (flexible and rigid) independently and assess the impact of pre-rehabilitation and pre-maintenance conditions on pavement performance. (3) Prepare and submit an interim report that documents the research performed in Phase I and includes the details of the work planned for Phase II of the project. Following review of the interim report by the NCHRP, the research team will be required to make a presentation to the project panel. Work on Phase II of the project will not begin until the interim report is approved and the Phase II work plan is authorized by the NCHRP.
Phase II: (4) Execute the plan approved in Task 3. (5) Submit a final report that documents the entire research effort. The report shall be prepared in four separate volumes: a summary report, a report on maintenance of flexible pavements, a report on rehabilitation of flexible pavements, and a report on rehabilitation of rigid pavements.
The revised final report was submitted after additions and revisions to address panel comments.
The final report is available as NCHRP Web Document 47