Measuring the Regional Economic Impact of Transportation Access Improvements in the Context of a Large Metropolitan Region

Abstract

Transportation planners are increasingly recognizing the importance of access in enabling employment growth and better paying job opportunities for residents. Although regional economic impact analysis is often an important element of transportation investment evaluation by state departments of transportation, it can be particularly challenging for metropolitan area planners because existing economic modeling methods do not fully account for the multifaceted roles that transportation links play in affecting access within large, polycentric metropolitan areas. This article examines these issues and presents information from a study of the Chicago region, to evaluate statistical relationships of employment cluster size and wage levels to zonal differences in business-to-business connectivity and population connectivity. It presents elasticities of employment and wage impact associated with various access measures for different sectors of the economy. These findings point to the importance of transportation planners considering the impacts on connectivity to both population markets and employment centers when evaluating the potential economic implications of proposed transportation system improvements in large, polycentric metropolitan areas. The article then lays out directions for future research and practice to improve transportation project evaluation and planning.

Relationship of Regional, Freight, and Intermodal Market Access to Industry Location and Productivity

“…Graham ( 1 ) developed the concept of “effective density” to capture the combined effects of a zonal concentration of industry activity and a gravity model function that captures industry concentration in surrounding zones weighted by travel time proximity. Studies have shown that zones with a higher effective density of employment in specific industries have relatively higher levels of value added and wages per capita ( 37 – 39 ).…”

“…Some economic research studies have sought to isolate the differing industry-level incidence and causal roles of localization, urbanization, and knowledge economies ( 40 ). Others have attempted to distinguish differing roles of physical density, residential market access, and employment proximity within an urban area ( 39 ). The previously discussed business location literature can carry us further in providing insight into causal effects and limiting effects that apply to passenger movement, freight movement, and intermodal connectivity at different spatial scales.…”

“…However, it would take a much larger effort to extend this kind of data to also cover regional freight delivery and intermodal terminal access, and also extend the study to all other areas of the U.S. As the technology of transportation network modeling and geographic information systems is still evolving, such data will likely be developed in the future. For now, it is not surprising to find that the cross-sectional study approach is dominant in the published literature on connections between access, business location, and productivity (e.g., see [35][36][37][38][39][40]).…”