General approach to payment adjustments for flexible pavements

The quest for developing a payment adjustment plan for contractors consider ing several distress indicators simultaneously is hindered by three issues: (1) different measurement units for the distress indicators; (2) possible correlation among those indicators; and (3) variation in each of the indica tors. In this study, three procedures are compiled together to cope with th e preceding issues. First, normalization of each distress indicator is empl oyed to create a dimensionless indicator. Second, principal components anal ysis, a multivariate statistical technique, is applied to eliminate the pos sible correlation among the distress indicators. Finally, through a propose d reliability analysis procedure, the pay factor is determined by the ratio of the reliability of the uncorrelated principal components of the as-buil t pavement over that of the as-designed pavement. Reliability refers to the level of confidence that exists in the distress indicators, not to exceed a certain limit. The results showed that pay factors based on multiple dist ress indicators are usually lower than those based on one single indicator when the variation in influencing factors such as asphalt concrete thicknes s is large.