Since the Texas Transportation Institute released its 2015 “Urban Mobility Report,” urban transportation experts and advocates have unleashed thousands and thousands of words poking holes at its methodology, assumptions, and political agenda. (We’ve pitched in our fair share of those words, and perhaps more.)

Not a kind of urban mobility you'll find in the Urban Mobility Report. Credit: Chad Kainz, Flickr
Not a kind of urban mobility you’ll find in the Urban Mobility Report. Credit: Chad Kainz, Flickr


As one last entry to this conversation, we wanted to put together a sort of Cliffs Notes version of the problems with the UMR, skimmable by people who just want a quick overview of the issues, without all the background. So without any further ado, the top ten reasons to be skeptical of the “Urban Mobility Report”:

  1. Both TTI and media outlets claim that the UMR proves traffic is worse than at any time since 1982—but a major methodological change in 2009 makes comparisons before that date completely invalid.
  2. The UMR, in the words of Victoria Transportation Policy Institute executive director Todd Litman, “ignores basic research principles,” including failing to allow other experts to review its data and findings—the sort of “peer review” that is foundational to social science investigations.
  3. As the Brookings Institution’s Rob Puentes notes, the UMR measures mobility, not access. That is, cities get high scores if you can drive really fast—not if you can actually reach jobs or amenities in less time.
  4. In many cases, the UMR counts an inability to drive faster than the speed limit as “congestion.”
  5. Since 2009, the UMR has used traffic data from Inrix—but their reports tell a very different story than the numbers that Inrix reports publicly, which suggest that congestion has actually decreased, while the UMR claims that congestion has increased. TTI hasn’t explained how it reached the opposite conclusion as the organization that provides its data.
  6. Despite claims that they favor a mix of measures including transit and more density, the TTI’s travel time index actually penalizes cities that undertake measures that shorten work trips. The TTI scorecard perversely incentivizes sprawl and ignores the costs associated with longer trips.
  7. The UMR’s prediction that traffic will get much worse in the coming years is based on a model that simply pretends the last decade didn’t happen.
  8. In fact, the US reached “peak driving” in 2005, and the average number of miles driven per day has fallen by nearly 7 percent since then.
  9. The UMR says that adding road capacity will reduce congestion—but 92 of the top 99 places where congestion increased according to the UMR increased their roadway miles per capita. Building more roads won’t reduce congestion or improve access without land use changes and other transportation investments.
  10. The “Urban Mobility Report” is in fact a report just about driving. Public transit, walking, and biking—essential parts of the transportation network in any city—are almost entirely left out. If you walk, bike or take transit you simply don’t exist in the eyes of TTI.