Since the 1980s, Texas A&M University’s Texas Transportation Institute (TTI) has periodically trotted out updated versions of its Urban Mobility Report, which purports to estimate the dollar cost of urban traffic congestion. The report has been repeatedly debunked, but after a four-year hiatus, it’s back, and it’s making the same false claims based on the same discredited premises.
There’s so much wrong with this report that it’s impossible to fit all the criticisms into a single article. But to quickly summarize the lengthy case against the Urban Mobility Report (UMR), we’ve pulled together a kind of CliffsNotes version, skimmable by people who just want a quick overview of the issues, with links to other resources where they can go deeper.
Here, then, are the top twenty reasons to be skeptical of the Urban Mobility Report:
1. TTI claims that the UMR proves traffic is worse than at any time since 1982—but major methodological changes make these 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. The 2019 iteration of the report simply ignores the multiple, widely published critiques of its methodology.
3. As the Eno Foundation’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.” The 2019 report counts any reduction of freeway speeds from 65 miles per hour as “time lost to congestion” even if the posted speed limit is 50 or 55 miles per hour. It’s indefensible that this report treats the inability to break the law as a “cost,” especially when speeding is proven to be a major contributor to road fatalities.
5. The report fails to acknowledge that there’s simply no feasible way to build enough road capacity that all vehicles could travel at free flow speeds (often in excess of speed limits) every hour of the day. The cost of building such capacity would be vastly greater than the supposed “cost” of congestion, meaning that in reality the net cost of congestion is zero (or less).
6. The UMR completely ignores the effects of induced demand: building more road capacity stimulates more sprawling development patterns, and more driving, which actually aggravate congestion and lead to more pollution and higher costs for the public and commuters. The phenomenon of induced demand is now so well-established that its referred to as “the fundamental law of road congestion.”
7. Practical experience with capacity expansion has shown that wider roads don’t reduce congestion. In TTI’s own backyard, the multiple widenings of Houston’s massive 23-lane Katy Freeway have only produced more traffic and even slower travel times. There’s simply no evidence than more capacity reduces congestion.
8. It’s remarkable that as traffic engineers, the authors of the UMR ignore the fact that freeways carry the highest amount of traffic at speeds of about 45 miles per hour. (At higher speeds, car spacing increases and roads can carry fewer cars). Building enough capacity to allow 55 or 65 mile per hour speeds is vastly more expensive and less efficient than designing to accommodate a speed that maximizes throughput. This is advocacy for waste.
9. The UMR has no solution for congestion because it lacks a credible explanation as to why congestion exists in the first place. While the report acknowledges (p. 12) the “imbalance” between demand and supply, it fails to consider that the fact that we charge a zero price for road use means that demand inevitably overwhelms supply in urban areas. As I’ve illustrated with the Ben and Jerry’s seminar on transportation economics, a zero price for a valuable commodity is the cause of congestion and queueing.
10. The UMR claims that congestion got worse every year between 2009 and 2014, but contemporaneously published data from Inrix (supposedly the source of the UMR estimates)—show that nationally congestion declined by about 30 percent during these years, due largely to a decline in vehicle miles traveled. Inrix has disappeared this data from its servers, and the Texas Transportation Institute has never explained the discrepancy.
11. Despite claims that they favor a mix of measures including transit and more density, the TTI’s travel time index actually penalizes compact cities and places that undertake measures that shorten work trips. The TTI scorecard perversely incentivizes sprawl and ignores the costs associated with longer trips.
12. The UMR purports to show that commuters in some areas are much worse off due to congestion, but survey data show that there’s simply no correlation (if not a reverse correlation) between the UMR’s key metric (the travel time index) and self-reported satisfaction with the urban transportation system. People who live in more congested places are not less happy with their urban transport systems than people who live in less congested places.
13. 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.
14. The report greatly exaggerates the value commuters attach to travel time savings. The report calculates the value of travel time at $15 per hour, but actual experience with High Occupancy Toll lanes, where people have the option in real-time to buy a faster trip, shows that the typical traveler values travel time at just $3 per hour; this single adjustment would lower the supposed value of time “lost” to congestion by 80 percent.
15. The UMR says that adding road capacity will reduce congestion — but 92 of the top 99 places where congestion increased according to the previous 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.
16. 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. The UMR actually notes (p. 15) that it excludes data on people walking: “The proprietary process filters inappropriate data (e.g., pedestrians walking next to a street)” This is the sole reference to “pedestrians” in the entire UMR; the word “bike” also appears just once. If you walk, bike or take transit you simply don’t exist in the eyes of TTI.
17. The UMR has just a single reference to safety, in a section dealing with autonomous vehicles. There’s no acknowledgement that higher road speeds and more VMT are strongly correlated with increased crashes and traffic deaths. More driving means more dying.
18. Here’s a list of words you won’t find in the Urban Mobility Report: sprawl, pollution, emissions, injuries, deaths, carbon, climate, VMT, induced demand, pricing, tolling. Trying to talk about urban transportation systems without considering their effects on these other pressing problems is a measure of how detached the UMR is from the reality of the 21st century.
19. The 2019 UMR has carefully avoided any references to tolling or road pricing, the one approach to congestion management that’s been proven to work in cities around the world. The 2015 UMR specifically recommended high occupancy toll lanes as a possible solution; the new report (p. 13) omits even that recommendation.
20. The UMR creates a fictitious time trend by ignoring changes in its methodology. To support its claim that congestion is increasing, the UMR reports data going back to 1982 even though TTI’s methodology has changed several times since then. An early model didn’t actually measure congestion: it simply assumed that increased vehicle volumes automatically produce slower speeds, which is not necessarily accurate. The report’s data from 2007 and earlier isn’t comparable the data that comes afterwards, and can’t legitimately be used to make claims about whether traffic is better or worse than in earlier periods.