Congestion report pushes sprawl through flawed analysis
The Texas Transportation Institute today released the final version of their report on congestion, which ranks the DC area tied for first with Chicago in hours wasted in traffic. Unfortunately, the report's methodology completely misleads as to the seriousness of traffic, and TTI is pushing the wrong policy solutions.
The TTI report narrowly looks at only one factor: how fast traffic moves. Consider two hypothetical cities. In Denseopolis, people live within 2 miles of work on average, but the roads are fairly clogged and drivers can only go about 20 miles per hour. However, it only takes an average of 6 minutes to get to work, which isn't bad.
On the other hand, in Sprawlville, people live about 30 miles from work on average, but there are lots and lots of fast-moving freeways, so people can drive 60 mph. That means it takes 30 minutes to get to work.
Which city is more congested? By TTI's methods, it's Denseopolis. But it's the people of Sprawlville who spend more time commuting, and thus have less time to be with their families and for recreation.
Sadly, despite CEOs for Cities pointing out these methodological problems last year, TTI went ahead and finalized its report without fixing them (PDFs). TTI ranks Portland as worse than Nashville, with a Travel Time Index (TTI) of
1.23 1.15 for Nashville and 1.15 1.23 for Portland. However, because of greater sprawl, Nashville commuters spend an average of 268 hours per year commuting, while the average Portland commuter spends 193 hours per year.
What does this mean for public policy and the Washington region? TTI's data is often used to justify spending money on new freeway capacity, since congestion sounds bad. TTI even promotes this approach. Tim Lomax, a co-author of the report, told the Post's Ashley Halsey III, "You can do little things like stagger work hours, fix traffic-light timing and clear wrecks faster, but in the end, there's a need for more capacity."
"That we are congested is not news, but TTI's report does tremendous damage, because they fail to recognize the primary cause of our congestion and imply that we could simply widen roads to build our way out of the problem," said Stewart Schwartz, Executive Director of the Coalition for Smarter Growth.
What Lomax didn't say, and which Halsey didn't print even though he should know better, is that there are other approaches besides those "little things." What you can do is concentrate future growth around existing hubs with more residents, jobs, and multimodal transportation.
That's what the Metropolitan Washington Council of Governments (COG) is trying to push with its Region Forward plan and the related "What Would It Take?" scenario (PDF). These involve focusing development in places like Tysons Corner and the Route 1 corridor in Fairfax, around underutilized Metro stations in Prince George's, future ones in Loudoun, and MARC and VRE hubs in Maryland and Virginia.
Arlington achieved substantial job and resident growth in its Rosslyn-Ballston corridor without adding to traffic congestion, as has Montgomery with growth in Silver Spring and Bethesda and DC development in places like NoMA and the Capitol Riverfront area. Regional leaders should be less concerned with speeding up existing cars, which just leads to sprawl farther out, and invest more in finding ways to grow the region without adding traffic.
In fact, that's just what the DC region has done. Another, better part of TTI's analysis measures the amount of time savings that come from each region's transit; DC is 3rd best. That metric still doesn't account for the value of people living nearer to their jobs, however.
Between better location and transit, to page 50, congestion has not increased since 1999 even on TTI's flawed scale. That means our region has been successfully growing without adding traffic. Instead of "Washington area tied with Chicago for traffic congestion, study finds," this morning's Post headline this morning could have read, "Washington area's traffic hasn't gotten worse in a decade thanks to smart growth."
It's more than a little baffling, though, that Halsey didn't make any reference to the CEOs for Cities report or the COG work. He also wrote, "Researchers said the depth of the data used in this year's study far surpassed the quality of information used in past years, giving the results an unprecedented degree of accuracy."
So, the researchers at this supposedly very highly regarded institute say that their data is super great, but they and the reporters ignored the widely-publicized critiques of their methodology. Maybe it's time for TTI to stop being so highly regarded.
- Vision Zero won't be easy
- For DC Council: Elissa Silverman and Robert White
- First flowerpots, and now, a cycletrack
- The Purple Line will likely beat ridership forecasts
- In Maryland and Virginia, vote to build transit
- Ask GGW: How much pain will riders face while Metro replaces the Bethesda escalators?
- Flowerpots create a safer pedestrian crossing from Gallaudet to Union Market