Interactions between transportation capacity, economic systems, and land use

This research report is based on 100 detailed case studies that document the long-term, before and after economic impacts of a variety of highway capacity investments, mainly from around the United States. This project focused on long-term impacts on performance metrics such as employment, income, real estate values, and tax revenues. Temporary, construction-phase impacts were not considered in the report or the database of case studies. The report presents documentation on the background of the research project, an explanation of how the case studies were selected and developed, an introduction to the accompanying web-based tool, and a meta-analysis of the key relationships among factors such as project type, traffic volume, project location, and non-transportation policies put in place to help foster economic development. The findings from the meta-analysis can serve as a high-level guide for transportation agencies in selecting highway capacity projects that, with regard to long-term economic impacts, will provide a greater return on investment. For instance, the meta-analysis indicates that the type of project (e.g., an interchange versus a ring road) and the setting (e.g., in an area that is economically distressed versus non-distressed) matter considerably more than the amount of money spent to build the project. This report and the accompanying T-PICS (Transportation Project Impact Case Studies) website are intended to serve as a resource for transportation planners and others who are interested in better understanding the long-term economic impacts of highway capacity projects. Although highway projects are the primary focus, a number of intermodal projects (e.g., transit-oriented development projects with both a substantial highway component and freight terminals) are included in the database and web tool. The database and web tool were designed so that future highway case studies and economic impact case studies involving other modes of transportation can be added as they become available.