Performance-Based Pay Factors for Asphalt Concrete Construction; Comparison with a Currently Used Experience-Based Approa ch

摘要

The paper briefly summarizes a procedure to quantitatively establishpay factors for asphalt concrete pavement construction usingperformance models for fatigue and rutting based on the analysis ofaccelerated pavement tests from the Caltrans Heavy Vehicle Simulator(HVS) and the WesTrack accelerated pavement performance testprogram. For rutting, the influence of asphalt content, airvoid content,and aggregate gradation are considered. For fatigue, airvoid content,asphalt content, and asphalt concrete thickness are included. Costs areestablished using a cost model considering only agency costconsequences of delaying or accelerating the time to the nextrehabilitation. For the as-constructed mix, the relative performance(RP)—the ratio of off-target ESALs to target ESALs—is determined forboth fatigue and rutting. The shortest RP for the combined RP’s for mixand pavement characteristics considered for a specific distress modepermits determination of the pay factor from the cost model.Pay factors determined by this methodology are compared with thosethat have been used by the California Department of Transportation(Caltrans), termed an experience-based approach. This set of pay factorshas been in use since 1997 for Quality Control/Quality Assuranceprojects. Comparisons are included for approximately 80 projectsconstructed in the period January 1997 to June 2000. Only a limitednumber of these contained measured rutting and fatigue cracking datathat had been incorporated in the Caltrans Pavement ManagementSystem. Comparisons of pay factors for these projects determined by thetwo methodologies are also included. An analysis is presented whichcompares pay factors calculated at the end of the project based on thetotal tonnage to the average of the pay factors based on the daily totaltonnage.A computer application using the performance based approach isalso included.