Estimating economic impacts from transportation investments using the Texas Statewide Analysis Model and TREDIS

Abstract

Economic analyses of transportation investments are a common component of transportation planning. The profile of economic analyses has continued to rise due to increasing budget constraints and increasing emphasis on infrastructure's role in spurring economic development. One tool that has been developed specifically for transportation economic impact evaluation is the Transportation Economic Development Impact System (TREDIS). Common inputs for TREDIS are changes in travel characteristics caused by network improvements. Another commonly used planning tool is a travel demand model. Since 2003, the Texas Department of Transportation (TXDOT) has worked on the development of the Statewide Analysis Model (SAM) which estimates travel characteristics for passenger and freight modes. Together, the models have the potential to improve project evaluation and to highlight the roles that certain projects have in creating economic development. The hypothesis explored for this study is that SAM and TREDIS can be feasibly used together to help TXDOT evaluate the economic impacts of investments in freight corridors and other transportation investments. This report begins with general discussions of transportation economic analyses and the two models used. Then, the current SAM is evaluated using TREDIS followed by a discussion of the results and ways that this type of integrated planning can be incorporated by agencies. Through this study, key results include: the process of incorporating results from the SAM for use in TREDIS is feasible, an overall benefit-cost ratio of 4 for the entire set of long range roadway projects included in the SAM and 8 for only the interstate projects included in the SAM, rail and other transportation analyses are feasible using SAM and TREDIS.