Case Studies of Pavement Forensic Investigation in California

A critical tool for pavement evaluation, forensic analysis, helps to identify the causes or mechanisms that may have led to a pavement’s premature distress or failure. This paper recounts two recent pavement forensic investigations conducted by the California Department of Transportation (Caltrans) in the interest of sharing the process and experience. The first investigation is on the California state route 99 in Merced County where a section of Asphalt Concrete Pavement (ACP) showed severe water pumping, potholes, and random reflective cracking. The forensic investigation began in the summer 2002 and included several activities: records review, field survey, deflection testing, field sampling and laboratory testing, and structural evaluation. These measures helped to isolate the causes of the premature pavement failure and facilitate an effective rehabilitation strategy. The second investigation is on the California state route 82 in San Mateo County. The prematurely failed ACP exhibited various pavement distresses including rutting, shoving, depression, bleeding, and potholes at random locations. Pavement samples were obtained from the project site and tested in the laboratory for relevant material properties. These tests helped to determine the causes of the pavement premature failure and facilitate the formulation of an effective strategy for repair and rehabilitation.