Getting Trip Generation Right: Eliminating the Bias Against Mixed Use Development

PAS Memo — May-June 2013

By Jerry Walters, Brian Bochner, Reid Ewing


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When planners, developers, or traffic engineers conduct traffic impact analyses for proposed developments, they typically use the trip-generation data and analysis methods published by the Institute of Transportation Engineers (ITE) in its Trip Generation report and Trip Generation Handbook. However, these conventional methods fail to account for the benefits of mixed use and other forms of lower-impact development; they exaggerate estimates of impacts and result in excessive development costs, skewed public perceptions, and decision-maker resistance.

This PAS Memo article explains the MXD+ method of traffic generation analysis for mixed use developments, which combines the advantages of two major studies' methodologies to increase accuracy, allowing for more appropriate on-site design features and off-site mitigation measures.


Page Count
Date Published
May 1, 2013
Adobe PDF
American Planning Association

About the Authors

Jerry Walters

Brian Bochner

Reid Ewing
Reid Ewing is a Distinguished Professor of City and Metropolitan Planning at the University of Utah, associate editor of the Journal of the American Planning Association, and columnist for Planning magazine. His 10 books include Pedestrian and Transit Oriented Design, co-published by the Urban Land Institute and American Planning Association; and Best Development Practices, listed by the American Planning Association (APA) as one of the 100 “essential” books in planning over the past 100 years. His 100 peer reviewed articles include “Travel and the Built Environment: A Meta-Analysis,” given the Best Article of 2010 Award by the American Planning Association. A recent citation analysis by Virginia Tech found that Ewing’s work is the 5th most highly cited among 1,100 planning academics in the U.S. and Canada.