Relationship of Transportation Access and Connectivity to Local Economic Outcomes

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.