Algorithm for Determining Weight Factors of Pavement Distress Index

Distress is one of the primary measurements of pavement condition. Thus, in a pavement evaluation program, distress type, severity, and extent should be properly identified. A pavement distress index (PDI) may be calculated by mathematically combining the effects of distresses on pavement conditions. Before the calculation of PDI, each distress attribute must be assigned a weight factor and a severity factor. An analytical algorithm that converts the subjective rating values of distress attributes to a rational weighting scale that provides quantified measurements of the effects of each distress on pavement damage and riding quality is presented. A case study for applying this procedure to the pavements of roadway samples from the Highway Bureau and the National Freeway Bureau in Taiwan also is presented. Through the analysis procedure, it was found that pothole has the largest weight factor (100) and that longitudinal crack has the lowest (49). The severity factors vary from 0.24 to 1.00, depending on the distress type and severity level.