The study, "Implementable Strategies for Shifting to Direct Usage-Based Charges for Transportation Funding," was commissioned by AASHTO through the National Cooperative Highway Research Program. Senate Environment and Public Works Committee Chairwoman Barbara Boxer, D-CA, has expressed strong interest in examining the potential for implementing in the near term a fee based on vehicle miles traveled.

"We think this report does an excellent job of examining the issues that surround a shift from a motor-fuel tax to a direct user charge based on miles driven," said John Horsley, AASHTO executive director. "As the nation's vehicle fleet changes to hybrid or electric cars, at some point in the future fuel taxes will no longer be an accurate reflection of highway usage -- the principle on which our highway funding has been based. This report highlights possible options, and the work that must be done to identify the right choices."

In its introduction, the report states: "For close to a century, motor-vehicle fuel taxes have been the primary source of funds supporting construction and operation of the nation's highways. Adopted as a means to charge road users for the costs of the system, these taxes are levied on a cents-per-gallon basis and must periodically be raised to offset the effects of inflation. The reluctance of many elected officials to make such increases, combined with improvements in fuel economy, fluctuations in travel, and the prospect of increasing reliance on alternative energy sources, have undermined the effectiveness of fuel taxes as a reliable revenue source. VMT fees are seen by many analysts and policymakers as a potentially viable way to generate revenues while maintaining the idea that users should pay for the system, an idea that originally gave rise to our current fuel taxes."

The report continues, "Directly charging road users based on their VMT or other indicators of their system usage has long been applied to travelers on toll roads. New electronics and communication technologies are making the idea increasingly attractive as a more broadly applicable revenue-raising tool. Many proponents envision that implementing direct charging will also enable more efficient management of the highway system, for example through pricing that varies by time of day and location to reduce congestion."

The report examined nine potential VMT systems ranging from self-reporting of odometer readings to various on-board recording units. It analyzed each from the standpoint of ability to capture mileage across the entire road system, cost, enforceability, and level of burden on state administrators and users.

Three options emerged as most promising. Those include mileage estimates based on fuel consumption, onboard units using cellular tracking, and on-board units utilizing GPS technology. The report examines the risks and benefits of each and also identifies strategies that can be implemented now to position the country for a phased-in transition beginning in 2015. These include planning investment, analytic studies, research and development, multi-state VMT system trials, and public education and outreach.

The 150-page report is available at tinyurl.com/TRB-VMT.