Development of a Fuel Consumption and Mileage Allocation Model to Support Mileage-Based User Fee Research in Washington State

In 2012, concerned with a stagnating transportation revenue stream, policy makers in Washington State began exploring a per mile road usage charge (RUC) to replace the current fuel tax. In 2014, the legislature directed the development of a concept of operations for a RUC, including a long-term financial analysis. This directive required determination of a regional estimate of the effective fuel economy of the light-duty fleet. At the same time, the legislature called for an evaluation of the distributional impacts of the RUC, specifically for urban and rural drivers. To respond, a model for allocation of fuel consumption and the number of vehicle miles traveled (VMT) was developed. Information from national data sets on fuel economy and on numbers of VMT was assigned to state vehicle licensing records by use of a statistical matching process. After calculation of the fuel consumption of individual vehicles, the model was calibrated with institutionally reported estimates of statewide fuel consumption and numbers of VMT. The completed model estimated the fuel economy for the statewide light-duty fleet for calendar year 2014 to be 19.5 mpg, more than 10% less than corresponding national estimates. Application of the completed model to the distributional analysis results showed that drivers would tend to pay more in user fees than fuel taxes for classes of vehicles that are more fuel efficient than the statewide average. Virtually no differences in impacts to urban and rural drivers as classes statewide were found; however, a county-level analysis revealed that certain rural counties benefit from a change to a RUC.