Using TREDIS for Public Transportation Assessment

TREDIS has a series of features designed to facilitate the analysis of public transportation investment and service options. These include the following elements:

• Travel Time and Cost Savings - TREDIS incorporates all of the basic elements of economic impact and benefit, including those associated with changes in travel time cost and reliability for users of bus, train, and car modes. TREDIS incorporates a particularly sophisticated benefit assignment routine that allocates the savings in terms of money flows (for employers and for households) and non-money flows (that can be reflected in land or building values). It draws on research findings to show how both businesses and travelers share the benefit of commuter travel improvements.


• Intermodal Impacts - TREDIS is the only economic impact analysis system that is inherently multi-modal, and features unprecedented capabilities for tracking mode switching and cross-modal impacts (as featured in a recent TRB paper). This is particularly important for public transportation because many of the benefits of public transportation enhancement come from switching riders from cars to buses (mode switching impacts), and from additional benefits of reducing congestion growth on existing roadways (cross-modal impacts). TREDIS captures the economic benefits of both effects. 


• Access Impacts - TREDIS is the only economic impact analysis system that can calculate impacts of public transportation on labor markets, by affecting job opportunities for workers and workforce depth for employers. It uses findings from recent research to capture the threshold effects that public transportation improvements can have on labor markets, productivity and the attractiveness of a region for different industries.


• Customization - TREDIS is unique in its flexibility, allowing users to distinguish differences in driver/staff and vehicle occupancy for different combinations of vehicle types, trip purposes and peak/off-peak times. This customization is exploited in the TREDIS setup which can distinguish impacts on bus, commuter rail and intercity rail options. The ability to focus on peak periods also allows TREDIS to show economic larger impacts from public transportation than would otherwise occur from relying on 24-hour daily averages.


• Income Subgroups - A forthcoming feature of TREDIS will extend the economic impact analysis by utilizing a "social accounting matrix" developed by Minnesota IMPLAN Group, to assess how economic impacts are felt by households in different income categories. That can be particularly useful in showing how all elements of society, but particularly vulnerable low income households, can gain from public transportation enhancement.

Applications: Chicago RTA (bus, rail rapid transit), Toronto Metrolinx (bus, subway, light rail, commuter rail), Portland Metro (light rail/multi-modal), Massachusetts (commuter rail), Chicago METRA (commuter rail). See Case Studies.