New data from Tom-Tom shows Portland number one nationally in reducing traffic congestion:  Where’s the celebration? 

Portland chalked up the biggest reduction in traffic congestion of any city in the US over the past year. But neither the media nor the state transportation department seem to care.  If what they’re doing is working, why aren’t they taking credit, and doing more of whatever it is seems to work?

The favorite click-bait of traffic monitoring companies like Inrix and others is using their big data on traffic speeds to produce rankings of which cities globally have the worst levels of traffic congestion. As we’ve regularly pointed out at City Observatory, it’s mostly a lot of shoddy and misleading pseudo-science.  The most commonly used measure of congestion, the travel-time index, computes how much longer a typical trip takes a the rush hour than at say, 2 AM, and treats the difference as the “cost” of congestion. That exaggerates the true cost of congestion (no one expects to have zero traffic at rush hours), and importantly inter-city comparisons ignore the wide differences in travel distances, especially commuting distances across cities, with the result that these measures invariably make sprawling cities with extremely long commutes appear to be less congested that more compact cities, where people actually spend less time commuting (even if they’re moving more slowly).

The latest set of congestion rankings comes from Tom-Tom, maker of an in-car navigation system. It aggregates data from its users to see how fast traffic moves in different cities at different times.  These studies are based on questionable methodologies and have some built-in biases. As Felix Salmon pointed out a couple of years ago, the TomTom data is gathered from people who’ve bought the devices, who almost by definition are not typical commuters. It’s highly likely that they represent those who drive the most, and who drive most in peak traffic (hence the value of Tom-Tom’s services); but data gathered from these devices is not necessarily typical of the experience of the average commuter.

While there are good reasons to doubt the level of congestion reported by Tom-Tom, the pattern of congestion across cities is similar to other estimates. Unsurprisingly, large, economically prosperous cities tend to have higher travel time indices than smaller cities and economically struggling ones.  For example, New York, Los Angeles, San Francisco, and San Jose are all in the top five of US cities; Akron, Syracuse, Kansas City and Cleveland are all in the bottom ten (of 80 ranked US cities.) Other studies show similar patterns:  traffic is a pretty strong correlate of a robust economy, and traffic tends to be greater in big cities than small ones.  Not much information here.

The big question about traffic is not this pattern of variation across cities, but what, if anything can be done to make traffic congestion less in the city you live in.  So you’d think that we should pay a lot of attention to which cities are reducing congestion, to see what’s working.

One of the long time meta-messages of these traffic surveys is a claim that traffic is bad and steadily getting worse.  That’s undoubtedly why these reports are the favorite grist for the highway lobby. This was the refrain of the grand-daddy of these reports, the Texas Transportation Institute’s (TTI) Urban Mobility Report–which thankfully hasn’t been prepared for almost five years, and may finally be dead.  We showed that the claim of steadily worsening congestion was an artifact of the way TTI, estimated speeds, and not an actual observation, and that it was contradicted by other sources of information. Inrix, which for a time published monthly data on traffic for US cities, showed big declines in traffic congestion between 2010 and 2013–when gas prices were high. (Inrix has since disappeared this data from its website).

What’s interesting is to look at what the Tom-Tom data show about how much measured congested has changed since last year. The 2018 data show some cities have actually made noticeable improvements in traffic flow in the past year. Overall 23 of the 80 US cities in the Tom-Tom list showed at least some decline in reported traffic congestion. At the top of the list is Portland, Oregon:  Portland recorded a 3 point reduction in its travel time index, falling from 1.27 to 1.24, meaning that in 2018, a peak hour trip took about 24 percent longer than an off-peak trip, rather than 27 percent longer.

You’d think, for all of the concern that the media and highway departments express about congestion that this news would be met with jubilation. But you’d be wrong. So far, Portland’s number one performance in reducing traffic congestion generated exactly zero media coverage by the city’s newspaper of record, the Oregonian, and other local news outlets.  Nor is there any mention of the data on the Oregon Department of Transportation’s website. (Web searches conducted June 6, 2019, two days after the release of the Tom-Tom report).

There’s a calculated asymmetry here: You can bet that if Portland had the biggest increase in congestion per TomTom, it would be a front page story on the Oregonian, and a regularly repeated talking point by the Oregon Department of Transportation. If you’re a highway engineer, or traffic reporter, drawing attention to the terrible (and worsening) nature of congestion is a big part of the way you justify your existence.  But good news, it seems, is no news.  If there were any science or objectivity here, you’d think that the media would be celebrating this success (and praising the policies that led to it), and that the transportation agency would be looking to do more of whatever it was that made the congestion numbers improve.

The reason for this asymmetry, as we’ve suggested before at City Observatory, is that for all their bloviating to the contrary, highway departments really don’t care about reducing traffic congestion. Traffic congestion statistics and rankings are simply convenient public relations fodder for selling the next big highway construction project. If they were serious about reducing traffic congestion, these highway engineers would have looked seriously at the big declines in traffic congestion in the early part of this decade (thanks to higher gas prices), and the decline in traffic generated by tolling congested roads, like I-65 in Louisville, and moved aggressively to implement congestion pricing, which is the only strategy that’s been shown to be effective.  But building things, not solving traffic problems, is really their priority.