New Report: Cities "Driven Apart" by Sprawl
Highway traffic outside of Chicago.

A new report examines the real reason behind traffic congestion in large American cities, like Chicago. Photo by Steven Vance.

A new report by CEOs for Cities analyzes transportation in 51 major U.S. cities, with an emphasis on land use patterns and community design, calling into question the highway-oriented industry standard for measuring congestion created by the Texas Transportation Institute’s annual Urban Mobility Report (UMR).

In large U.S. cities, peak hour travel times average 200 hours per year. But data from the new report show that time spent stuck in traffic can be reduced by following the lead of cities like Chicago, Portland and Sacramento, which have land use patterns and transportation systems that allow residents to take shorter trips. The conclusion? Traffic jams aren’t caused by more cars and fewer highways; it’s sprawl. (See this infographic to learn more.)

The report, titled “Driven Apart: How Sprawl Is Lengthening Our Commutes and Why Misleading Mobility Measures Are Making Things Worse,” reevaluates the justification for spending billions of dollars on new roads to deal with congestion. According to the report, policy making should instead center on how cities are structured and built, not roads themselves. The key is that compact, multi-use development brings many benefits, including savings in time (spent in traffic) and money (spent on highways.) Unlike the UMR, “Driven Apart” includes metrics that focus on trip distances and total travel times, revealing drastically different findings:

Driven Apart ranks how long residents in the nation’s largest 51 metropolitan areas spend in peak hour traffic, and in some cases the rankings are almost the opposite of those listed in the 2009 Urban Mobility Report. For instance, the UMR depicts Chicago as having some of the worst travel delays, when it actually has the shortest time spent in peak hour traffic of any major US metro area. In contrast, Nashville jumped from 31st to first on the list of those with the longest peak travel times.

The divergent findings of the two reports means  Texas Transportation Institute’s analysis of congestion and the road needs of U.S. cities is skewed, according to CEOs for Cities. The UMR ranks the five worst U.S. cities for congestion as follows:

  1. Los Angeles – Long Beach, CA
  2. Washington DC-VA-MD
  3. Atlanta, GA
  4. Houston, TX
  5. San Francisco- Oakland, CA.

In contrast, “Driven Apart” finds these to be the worst cities for peak period travel:

  1. Nashville-Davidson, TN
  2. Oklahoma City, OK
  3. Birmingham, OK
  4. Richmond, VA
  5. Raleigh-Durham, NC.

The problem is that the UMR does not take into account travel distances but instead “rewards cities that are spread out as opposed to compact urban areas.”  CEOs for Cities says UMR’s central analytical tool, Travel Time Index (TTI), is an outdated mode of analyzing travel time – it looks at the ratio between average peak hour travel time and average free flowing travel time. Given the variation in city land use patterns and densities, this analysis does not tell a complete picture. The UMR focuses on a single aspect of urban transportation: the number of additional hours travelers spend during peak hours due to congestion.  One example the author points out is San Francisco versus Kansas City.

..if one looks only at delay, one would assume that peak travel was much more onerous in San Francisco than in Kansas City: the average San Francisco commuter faces, according to the UMR, 40 more hours of delay annually than that of her Kansas City counterpart (55 hours versus 15). But the total travel time picture appears to be the opposite, when working with the UMR’s summary statistics.  The Kansas City commuter spends 229 hours per year in peak hour traffic, compared to just 186 hours for her San Francisco counterpart…

In fact, in many metropolitan areas, the effects of congestion have been offset by shorter travel distances.Driven Apart” says UMR’s findings are not consistent with other measures of travel and observed changes across cities in the U.S.  The UMR targets car-based congestion as a waste of tens of billions of dollars but does not look at accessibility, trip distances and land use patterns.

Considering that transportation is the second highest expense for many working families, it is important that cities address transportation in relevant ways by continually refining methodologies for shaping policy, not simply focusing on vehicle speeds and highways. Thus, as CEOs for Cities Senior Policy Advisor Joseph Cortwright summarizes in “Driven Apart,” the U.S. Department of Transportation needs appropriate standards for designing and selecting metrics for urban transportation systems. Useful measures should do more than draw attention to a problem. They should, instead, “…shed light on the nature and causes of these problems and help send clear signals about which policies and investments are likely to have the greatest efficacy in addressing those problems.”

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