How Does it Work? TREDIS is comprised of four modules" that work together to determine the full economic impact of transportation projects. Any single module or combination of modules may be used independently of the others.

Travel Cost Module (TC). The first module translates changes in traffic volumes, travel times and accidents into direct cost savings that accrue to households and businesses.

Market Access Module (MA). The second module translates changes in regional accessibility and intermodal connectivity into effects on productivity and business relocation.

Economic Adjustment Module (EA). The third module incorporates a dynamic regional economic impact model to estimate total impacts on growth of the study area economy over time.

Benefit-Cost Module (BC). The fourth module of TREDIS calculates the net present value of project benefits and costs from the differing perspectives of federal, state and local agencies.

The TREDIS modeling framework is designed as a seamless tool to analyze the economic impact of transportation projects “from scratch.” However, it can also be “broken apart” so that each of the four modules may be used individually, in any combination with one another, or in conjunction with a user’s in-house substitute. For example, a user may already have estimated the direct effects of a transportation policy, and is only interested in the market access effects and secondary impacts. In this case, TREDIS’ Travel Cost Response and Benefit/Cost Accounting module may be circumvented.