AN ASPHALT PAVEMENT RATING SYSTEM BASED ON HIGHWAY MAINTENANCE ENGINEERS' EXPERIENCE

Research was conducted at The University of Alabama for the State of Alabama Highway Department (AHD) to define the relationship between asphaltic pavement distress and the opinions of experienced highway maintenance engineers. Seasoned maintenance engineers evaluated a series of sites across the state to determine the required level of maintenance. Thirty-one inspectors rated 1,086 sites in terms of minor maintenance and overlays of structural rehabilitation. The ratings were based on a linear scale calibrated to maintenance needs through a Delphi study. Following the inspections, the engineers' ratings were correlated to distress measurements at each site. An extensive regression study produced a model that was strong, with an R-square value of 0.74 and a small standard error. The research staff and highway department engineers were quite pleased with the strength of this model. The AHD now measures pavement distress for a test section of each lane-mile, and applies the predictor model to yield a numerical score equivalent to the rating of maintenance engineers. This is the key to the required level of maintenance. It allows prompt tabulation of the required statewide maintenance, and development of a priority listing for completing the work.