TRB¿s National Cooperative Highway Research Program (NCHRP) Report 623: Identifying and Quantifying Rates of State Motor Fuel Tax Evasion explores a methodological approach to examine and reliably quantify state motor fuel tax evasion rates and support agency efforts to reduce differences between total fuel tax liability and actual tax collections.

Conference participants sought to identify gaps in the data and analytic tools needed to support economic analysis as related to transportation investment and to develop research proposals designed to fill those gaps. The opening day of the conference featured presentations by economists, transportation analysts, and policy makers on the theory and practice of economic analysis and its usefulness to decision makers. The second and third days of the conference revolved around participatory workshops. Six separate working groups deliberated over three questions: (1) What is the appropriate level of investment in transportation to encourage economic health? (2) How should projects be prioritized within a multimodal transportation program? (3) How much revenue is likely to flow from user charges, tolls, and other sources? At the conclusion of its deliberations, each working group developed a list of research proposals, which it then presented to the conference as a whole.