U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
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Publication Number: FHWA-RD-06-067
Date: March 2006
Because all of the sections in the LTPP program are located on public roads, some form of modification to the pavement structure will likely be needed to keep the road in a safe and serviceable condition for the traveling public. The data collected will pertain to rehabilitation that has occurred after initiation of monitoring for the test section. Most rehabilitation procedures, such as recycling or overlay, produce a test section having a modified pavement structure, while other procedures, such as undersealing, may be considered to restore the existing pavement structure. Reworking shoulders and placement of edge drains are other examples of improvements that may be made without changing the primary pavement structure; however, any such rehabilitation converts the pavement from an original pavement to a rehabilitated pavement. In other words, rehabilitation activities change the structural response of the pavement test section.
When a test section is modified by application of a rehabilitation treatment, some minimum requirements must be met for it to continue to be monitored as part of the LTPP program. Chapter 7 of the DCG as identified by the following reference governs the collection of data with respect to rehabilitation of the test sections.
Chapter 7 of this document provides the forms and specific guidelines for collection of information about rehabilitation treatments on test sections. Each of the following versions of the DCG had updates to chapter 7 governing collection of rehabilitation data.
Data Collection Guide for Long-Term Pavement Performance Studies, Operational Guide No. SHRP-LTPP-OG-001, SHRP, National Research Council, Washington, DC, December 15, 1989.
Data Collection Guide for Long-Term Pavement Performance Studies, Operational Guide No. SHRP-LTPP-OG-001, FHWA, Pavement Performance Division, McLean, VA, October 28, 1993.
Data Collection Guide for Long-Term Pavement Performance Studies, Operational Guide No. SHRP-LTPP-OG-001, FHWA, Pavement Performance Division, McLean, VA, February 19, 2004.
Some of the rehabilitation treatment types cause a section to be removed from further study. Others will cause the test section to be moved to a new experiment. The following document provides guidelines for types of rehabilitation treatments that do not require that the test section be removed from future study.
The following two documents superseded the April 1993 document regarding when a section that has undergone rehabilitation will continue to be monitored as a part of the LTPP program. Both of these documents were effective, via directive, as of September 24, 1998. The policy on monitoring continuation was further modified by directive GO–28 on November 7, 2001 to remove test sections from further study for any rehabilitation construction activity performed after January 1, 2004.
Long-Term Pavement Performance Guidelines for Monitoring Continuation on Rehabilitated Test Sections, FHWA, Pavement Performance Division, McLean, VA, August 1998.
Long-Term Pavement Performance Guidelines for Classification of Rehabilitated Test Sections, FHWA, Pavement Performance Division, McLean, VA, August 1998.
As stated previously, chapter 7 of the original DCG in combination with DCG chapter 6 has been organized into a separate document. Chapter 7 of the DCG and the two policies identified above have been superseded by the following document.