Congestion costing critique

17 Jun 2013

The Urban Mobility Report (UMR) is a widely-cited study that quantifies and monetises (measures in monetary units) traffic congestion costs in U.S. metropolitan regions. This report critically examines the UMR’s assumptions and methods. The UMR reflects an older planning paradigm which assumes that “transportation” means automobile travel, and so evaluates transport system performance based primarily on automobile travel speeds; it ignores other modes, other planning objectives and other impacts. The UMR methodology overestimates congestion costs and roadway expansion benefits by using higher baseline speeds and travel time unit cost values than most experts recommend, by ignoring induced travel impacts, and using an inaccurate speed-emission curve. Its estimates represent upper-bound values and are two- to four times higher than result from more realistic assumptions. The UMR claims that congestion costs are “massive,” although they increase total travel time and fuel consumption by 2% at most. It exaggerates future congestion problems by ignoring evidence of peaking vehicle travel and changing travel demands. The UMR ignores basic research principles: it fails to identify best current practices, explain assumptions, document sources, incorporate peer review, or respond to criticisms.

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