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The city of Portland is using research and expertise from TREC researchers to change how it calculates fees for new development. Developers pay the fees, called transportation system development charges, to offset some of the costs of providing transportation infrastructure.
 
The foundation for those fees has been cars: that is, how many car trips a development will generate. In December, the Portland City Council voted to instead use “person trips” as the basis for those fees.
 
Researchers Kelly Clifton and Kristina Currans have assembled an impressive portfolio of research projects on trip generation. Their research caught the attention of city officials, who brought Clifton and Currans in as consultants to help them rethink the way they assess new fees for development.
 
Their work found a receptive audience of practitioners at TREC’s flagship conference, the Transportation and Communities Summit, last fall. Clifton and Currans held a workshop on improving trip generation methods to better represent the mix of modes found in livable communities. That led to a collaboration with transportation consultants...

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OTREC research has taken steps toward developing trip generation rates for sites in a multimodal context.
Trip generation refers to the number of vehicle trips that are predicted to originate in a particular zone. The Institute of Transportation Engineers (ITE) provides standard trip generation rates, but these rates are primarily measured in low-density suburban areas.
In areas that have a more compact urban form, better access to transit and a greater mix of land uses, fewer (and shorter) vehicle trips might actually be generated there than the current ITE rates indicate.
A 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.
 
Results from this study reveal a trend: For all land uses tested, vehicle-trip rates decrease as neighborhood types become more urban.
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 the ITE rates...
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