Past research has shown that transportation system improvements can affect economic growth and productivity by changing access to markets and connectivity to intermodal terminals. However, most past research has adopted singular measures of market access and business productivity. This study demonstrates how various transportation projects can have larger or smaller impacts on business concentration and productivity by affecting different aspects of market access in areas with different business mixes. The study demonstrates these relationships through a two-step process. First, it defines seven types of access and connectivity measures, including access to labor markets, truck delivery markets, and intermodal terminals. The process then develops econometric models of the relationship between access and connectivity characteristics of local areas and relative levels of business productivity, job concentration, and export base. These relationships are estimated with simultaneous, nonlinear equations that allow access threshold effects to be recognized and for different relationships to apply for 54 industry sectors. The results confirm that different types of access are relevant to different industry sectors. As a consequence, the productivity and agglomeration of a given industry in a given area can be related to more than one dimension of accessibility. These results can have important implications for estimating the wider economic benefits of transportation investment and suggest the need to consider both industry detail and forms of accessibility in order to calculate accurately the relative impact of specific project proposals.

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.

This study explores how different asset management, traffic forecasting, performance, and economic models can be integrated to show the national economic implications of transportation funding and performance gaps under different scenarios. Asset management models have often been utilized to assess and forecast the condition and performance of current infrastructure. Travel demand models have been used to anticipate how traffic volumes are likely to develop over time depending on capacity improvements. User-cost models have been used for cost–benefit analysis and the management of trade-offs, and economic impact models have been used to characterize transportation choices in terms of earnings, output, and employment. This study explores how a sequence of these models when applied to a consistent data set with consistent assumptions can address the overall relationship between physical transportation system conditions and performance, traffic patterns, transportation costs, and economic impacts. The results point to a vertically integrated and economically defensible approach to needs-based planning with an understanding of the national economic significance of transportation investment choices.

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Benefit–cost analysis (BCA) is widely used for airport investment analysis, for both ranking of alternatives and funding decisions. Although the technique is theoretically straightforward, its application can become complicated by a series of factors that are particularly problematic for aviation applications. For one, the requirement for ground access makes air travel intrinsically multimodal. In addition, the speed of air travel attracts classes of users and dependent parties with particular speed sensitivities and delay consequences. When BCA is applied to airport project proposals, it can raise issues of how to handle competing modes and intermodal interactions, and the definition of the real users and beneficiaries of airport improvements. To examine these issues, the authors compared benefit–cost guidance for airports with counterpart guidance for other travel modes and conducted a review of the current state of practice of benefit–cost studies for airport improvements. The findings point to challenges for improving methods of airport BCA.