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Urban Mobility Report: Not Even the Title Gets it Right
Posted by Julia Klaiber on June 16, 2011 |
In a blog post highlighting the debate between Joe Cortright of CEOs for Cities and Tim Lomax of Texas Transportation Institute at the Congress for New Urbanism, Jarrett Walker discusses the flawed methodology found in the Urban Mobility Report. Agreeing with many of the points made in Driven Apart, Walker suggests much-needed updates to the Urban Mobility Report, starting with the name.
"Mobility is in the report title, but [it] is about congestion. ...The journalistic spin that TTI itself recommends is that non-car modes matter only if they reduce congestion, and that congestion remains the primary measure of urban mobility."
Walker specifically discusses a need to quantify the degree of freedom people have in moving about their city at will. This point resonates with Joe Cortright’s emphasis on the need to emphasize the accessibility of destinations when studying America’s traffic congestion.
Debating the True Cause of Congestion
Posted by Julia Klaiber on June 16, 2011 | News
At a Salon Session hosted by the Congress for New Urbanism on June 2, 2011, Joe Cortright, senior policy advisor for CEOs for Cities, debated Tim Lomax of the Texas Transportation Institute on the proper metrics for measuring traffic and congestion. The debate on congestion indices and urban accessibility focused on Driven Apart, CEOs for Cities’ critique of the Texas Transportation Institute’s Urban Mobility Report.
Driven Apart questions the methodology of the Urban Mobility Report. It specifically criticizes the Urban Mobility Report for using poor fuel estimates. In the debate, which you can view online, Lomax admits that that Texas Transportation Institute is “guilty of [poor fuel estimates]…[They] took an old model and tortured the hell out of it.” He offers no explanation for why TTI knowingly published the 2010 report despite this inaccuracy.
Driven Apart takes a look at what really causes traffic congestion in America. The report finds, contrary to the Urban Mobility Report, the 25 year-old industry standard for traffic assessment, that many metropolitan areas have actually seen reductions in average peak hour travel times. The reduced travel time reported in Driven Apart is reflective of shorter travel distances, improved land use patterns and personal choices about where to live and work. The importance of compact cities in reducing travel time points to major flaws in the national standard for measuring congestion and suggests new metrics are needed.
2010 UMR Remains a Flawed and Misleading Guide to Urban Transportation
Posted by Julia Klaiber on January 20, 2011 | News
Chicago, January 20, 2011 - The 2010 Urban Mobility Report released today by the Texas Transportation Institute does nothing to correct the problems identified in an independent analysis of the report released last year by Joe Cortright for CEOs for Cities. It continues to present an exaggerated and incorrect picture of the extent and causes of urban transportation problems and their solutions, and it fails to recognize the major contribution land use makes to time spent in traffic.
A detailed critique of the methodology and results of previous Urban Mobility Reports released by CEOs for Cities last October identified a series of flaws in the data and analysis in the UMR and outlined a series of improvements and alternative measures that can be used to assess urban transportation systems.
A first review of the 2010 UMR reveals the following concerns about its accuracy and usefulness:
Continues to rely on the Travel Time Index, which is built on the unrealistic baseline assumption that travel times should (and could) be no longer during peak periods as during non-peak periods and obscures the effect of land use patterns in creating longer travel distances.
Eliminates references to a misinterpreted 1981 study of fuel economy that was the basis of earlier fuel consumption estimates, but doesn’t explain how new numbers are generated and doesn’t allow for the fact that some speed reductions associated with traffic actually lower fuel consumption.
Replaces its inaccurate, model-based estimates of traffic levels with real world data from INRIX, but continues to rely on inaccurate speed volume models and has not corrected earlier over-estimated traffic congestion and associated economic costs.
Most importantly, by ignoring – and thereby concealing – the effects of longer travel distances in some cities, the UMR continues to get the ranking of cities with the worst travel problems wrong.
For example, consider Nashville and Portland. According to the UMR, Portland has a worse traffic problem than Nashville, with a Travel Time Index of 1.23. and 36 hours of delay per year per traveler, compared to Nashville, which has a Travel Time Index of 1.15 and 35 hours of delay. But these data also mean that the average peak traveler in Nashville has to spend a total of 268 hours per year commuting compared to the commuter in Portland who travels only 193 hours per year. So the commuter in Portland travels 75 fewer hours annually because of shorter travel distance, due in large part to less sprawling development patterns. Consistent with conclusions presented in Driven Apart, the UMR completely misses the importance of land use planning as a key to reducing the burden of peak period travel.
The Texas Transportation Institute has not yet released the documents showing the methodology used in the 2010 UMR. Nothing in the publicly released report indicates that the authors have rectified the problems identified in Driven Apart.
Click here for an official statement and longer summary of our initial review. CEOs for Cities will continue to examine the 2010 Urban Mobility Report and its supporting material and will report our findings at www.ceosforcities.org.
For an official comment by CEOs for Cities, please contact Julia Klaiber at 202-525-5627 or jklaiber@ceosforcities.org.
Driven Apart was generously supported by The Rockefeller Foundation.