| The development and maintenance of highway infrastructure in the US is becoming an important challenge due to increasing costs and revenues that are not adequate to meet the costs. Traditionally, fuel taxes have provided a significant portion of the revenues for the highway network. This research evaluates the impacts of changes in automobile and light truck fleet fuel economies, as well as hybrid and alternative fuel vehicles in the fleet, on gasoline tax based revenues. Vehicle sales, vehicle survivability, and fuel consumption data from 1980 to 2005 were used to estimate the fleet mix, Vehicle Miles Travel (VMT) by fleet mix, and revenue projections through the year 2025.;Six options were identified and evaluated to help address the revenue needs for highway financing: (1) gasoline tax as a fixed amount per gallon, (2) gasoline tax as a percent of the gasoline price, (3) toll based options, (4) user fee based on vehicle miles traveled (VMT), (5) tiered system of user fee based on VMT, and (6) user fees based on axle load and VMT. The results indicate that increasing the existing gasoline tax by 10 cents per gallon would not generate enough revenues to maintain the transportation infrastructure over time, unless they are indexed to the Producer Price Index (PPI). However in this scenario, hybrid vehicles and alternative fuel vehicles would not be paying their fair share for using the system. Tolling, when implemented for urban interstates at a rate of 10 cents per vehicle mile and indexed to the PPI, would generate enough revenues to maintain the system. A VMT based system, when implemented using the 1993 gasoline tax rate adjusted by the Consumer Price Index (CPI) would generate enough revenues to maintain the system. A tiered structure based on VMT, or an axle load and VMT based method would generate enough funds to maintain the system over the years provided the 2009 rate required to maintain the system is indexed to the CPI. Sensitivity analyses show that even with the revised user fee structures, there would be savings for the users of hybrid and alternative fuel vehicles.;The results indicate that the existing gasoline tax policy would not be able to generate revenues required to maintain and improve the US highway network in the years to come. Among the six options explored herein, the best alternative is a VMT based user fee. Further, it is important to index user fees based on either CPI or PPI. The implementation of the proposed options requires overcoming various challenges. Such challenges include political, behavioral, social, equity, economic, and technological considerations. In the meantime, it is important to continue with the existing gasoline tax policy and revise it to meet, at least partially, the increased need for revenues to maintain the highway system. |
