Testing the Effectiveness of Bicycle and Pedestrian Access Improvements in Reducing Commute Vehicle Trips

DKS Associates has led the development of the tool called the TDM Effectiveness Evaluation Model (TEEM) to help the Washington State Department of Transportation evaluate transportation demand management (TDM) strategies. DKS has included in TEEM a method for evaluating the effect of improving bicycle and pedestrian access to employment sites through physical improvements. The tool was based on research conducted by DKS and OTAK on the existing level of bicycle and pedestrian accessibility for all employers in King County that are participating in the State’s Commute Trip Reduction program. The research team developed an index of accessibility for both bicycle access and pedestrian access based on the extent of physical infrastructure to accommodate commuting by the two modes. Data on commute mode to work for all of the employees in the CTR database for King County was then correlated with the index values to produce a functional relation between the two. Estimates were also developed for the costs per acre of raising an index value one unit for an area. With these research results, it is possible to estimate the change in walk and bicycle commute mode shares that would result from a specified percentage increase in the index values and the cost of doing that. The new tool has been used to test the cost-effectiveness of bicycle and pedestrian improvements relative to other TDM options in the I-405 corridor of the Central Puget Sound region.