The effects of a transportation project can be estimated either by benefit/cost accounting or by economic development impact analysis, both of which are regularly used by government agencies to plan and justify investments. While these approaches differ in methodology, both rely on the estimation of direct user impacts those arising from changes in the quantity and quality of travel. However, a survey of published analyses and guides reveals, first, that there is considerable confusion between an economic benefit (as used in benefit/cost accounting) and an economic impact (as used in impact analysis), and second, that user impacts are frequently estimated too narrowly by ignoring intermodal effects and impacts to freight shippers. To address these issues, we present a framework for estimating direct user impacts that (1) is generalized to accommodate multiple travel modes in a way that avoids double-counting, (2) gives a full treatment of freight shippers and carriers, and (3) differentiates between benefits and impacts for use in either type of analysis.
Abstract