Rebuilding the Distress Thresholds for Pavement Warranty Program in Mississippi

Abstract

Pavement warranty is an innovative contracting procedure increasingly adopted by state transportation agencies to protect investment in pavement construction and maintenance. In Mississippi, the pavement warranty program was initiated in 2000 and the pavement distress thresholds were set based on the deduct points calculated by conversion equations from distress measurements of unacceptable pavement conditions. The conversion of distress measurements into deduct points using empirically regressed conversion equations has been questioned, however, on the grounds that it actually reduces the accuracy of the objective distress measurements by adding subjective and random errors. Moreover, the validity and applicability of continual use of these conversion equations has become problematic with time, because the equations were empirically developed in the 1990s, reflecting the data, experience, and technologies at that time. This research aims to develop analytically new distress thresholds based on direct measurements of pavement distresses for the pavement warranty program in Mississippi. The bootstrapping method was employed to process the skewed historical distress measurement data into normal distributions. The upper bound of confidence interval or standard deviations of the normalized distress measurement data was determined as an alternative method to rebuild the threshold for each distress type. The confusion matrix was employed to consider a smooth transition of updating the thresholds from the current deduct point based system to a new measurement based system. This study provides a practical procedure for developing a set of measurement based thresholds to renew the pavement warranty program using the available pavement management system data.