This synthesis report will be of interest to transportation agency planners; design, construction, and maintenance engineers; and administrators, managers, economists, and other decisionmakers involved in programming highway pavement projects. This synthesis describes current practice with regard to road user and mitigation costs in highway pavement projects. Information for the synthesis was collected by surveying U.S. and Canadian transportation agencies and by conducting a literature search of both domestic and foreign publications. This report of the Transportation Research Board provides detailed information on the various methods employed by transportation agencies to estimate user costs. The advantages and disadvantages of each are reported. Information on the various components of user costs (that is, time related, vehicle operating, safety, and environmental costs) is also included. In addition, the study reports on the various mitigation strategies available to agencies to reduce user costs. Information is also provided on how user costs and mitigation strategies have been applied to evaluate different alternatives; and how uncertainties, political considerations, and quality control contribute to the decisionmaking process.