A forensic study was conducted in May 2008 on two test sections that are a part of the Federal Highway Administration (FHWA) Long Term Pavement Performance (LTPP) 20-year program. It was decided to investigate the causes and mechanisms of decreased pavement performance and determine what may have contributed to the differences in performance of two rural pavement sections on the Lake Ontario State Parkway in New York State. An extensive amount of distress, deflection, environmental, construction, traffic and profile data was analyzed to establish trends as part of these investigations. Projected life cycles were calculated and compared using Empirical and Mechanistic-Empirical design methods. Issues with the pavement structure at the pavement terminal point were fully diagnosed through the use of non-destructive testing equipment coupled with validation coring and laboratory testing. The tools and methods found most useful will also be described together with examples from the forensic study. These sections failed prematurely due to a design unable to withstand environmental effects and due to lack of maintenance. The main focus of this paper is to illustrate how routine and systematic collection of quality data combined with a forensic pavement investigation can identify changes that need to be made to materials, design and construction practices or specifications which would eliminate similar problems in the future. Optimistically, this paper will identify the methods and analysis needed to help create more efficient and cost-effective practices in the reconstruction or rehabilitation of roads in these difficult economic times.
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