This research was funded by the National Institute for Transportation and Communities, or NITC, a program of TREC at Portland State University.
Trip generation -- United States, Traffic surveys -- United States, Transportation -- Planning -- Statistical methods
Trip generation refers to the number of vehicle trips that are predicted to originate in a given zone. The Institute of Transportation Engineers (ITE) publishes standard trip generation rates for various land use types, but these rates are primarily measured in low-density suburban areas. There is national interest in building data that expands upon the existing ITE trip generation rates to include sites located in a multi-modal context.
In areas that have a more compact urban form, better access to transit and a greater mix of land uses, fewer vehicle trips may be generated there than ITE rates indicate. However, there is a strong industry bias toward using ITE-published rates, so that when local governments are evaluating transportation impacts and calculating transportation system development charges, they are often compelled to use ITE rates instead of local data, especially in the absence of an empirically tested methodology for adjusting the ITE standard rates.
An OTREC project headed by Kelly Clifton, of Portland State University, examines the ways in which urban context affects vehicle trip-generation rates across a variety of land uses. In the study, Clifton developed a model to adjust ITE’s trip generation rates for urban contexts
Clifton, Kelly J. More Urban Form, Fewer Auto Trips. 2011-407. Portland, OR: Transportation Research and Education Center (TREC), 2014.