Usage-Based Highway Cost Allocation Among User Groups

Highway construction cost allocation for highway projects has been a controversial topic because of the equity issues of cost responsibilities and user fee charges. One of the major difficulties associated with highway cost allocation comes from the estimation of pavement damage by various vehicle classes. In the existing procedures, pavement damage is assessed using the Equivalent Single Axle Load (ESAL) concept, which was empirically developed after the AASHTO Road Test about half a century ago. The deficiencies with the ESAL concept have led to the estimation of pavement damage due to vehicle classes quite inaccurate. In this study, a more rational highway construction cost allocation approach is developed based on the recent progress in the Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National Cooperative Highway Research Program (NCHRP) Project 1-37A. With the MEPDG software, pavement deterioration under varying traffic loading and environment conditions can be simulated, and pavement damage due to different vehicle classes can be more realistically computed and compared, based on which the load-related cost allocation analysis can be more rationally performed. In a case study, actual traffic data collected at a weigh-in-motion station in Texas are used to set up for the simulation scenarios. Two cost allocators based on vehicle-miles-travel (VMT), i.e., VMT-Axle and VMT-Damage, proxy for vehicle size and weight respectively, are used to allocate the highway construction cost to three cost components in right of way (ROW) acquisition, load-related cost, and non-load-related cost for each of the vehicle classes.