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[email protected] 250-508-5150 Generated Traffic and Induced Travel Implications for Transport Planning 22 April 2021 Todd Litman Victoria Transport Policy Institute Abstract Traffic congestion tends to maintain equilibrium; traffic volumes increase until congestion delays discourage additional peak-period trips. If road capacity expands, peak-period trips increase until congestion again limits further traffic growth. The additional travel is called “generated traffic.” Generated traffic consists of diverted traffic (trips shifted in time, route and destination), and induced vehicle travel (shifts from other modes, longer trips and new vehicle trips). Generated traffic often fills a significant portion of capacity added to congested urban road. Generated traffic has three implications for transport planning. First, it reduces the congestion reduction benefits of road capacity expansion. Second, it increases many external costs. Third, it provides relatively small user benefits because it consists of vehicle travel that consumers are most willing to forego when their costs increase. It is important to account for these factors in analysis. This paper defines types of generated traffic, discusses generated traffic impacts, recommends ways to incorporate generated traffic into evaluation, and describes alternatives to roadway capacity expansion. A version of this paper was published in the ITE Journal, Vol. 71, No. 4, Institute of Transportation Engineers (www.ite.org), April 2001, pp. 38-47. Todd Litman 1998-2021 You are welcome and encouraged to copy, distribute, share and excerpt this document and its ideas, provided the author is given attribution. Please send your corrections, comments and suggestions for improvement. Generated Traffic: Implications for Transport Planning Victoria Transport Policy Institute Contents Introduction ....................................................................................................................