Putting numbers to drivers’ misery
When advocates for transportation improvements want to illustrate how bad the commute has gotten, they almost always cite their region’s high ranking in a national study of congestion prepared by the Texas Transportation Institute. Tim Lomax, a researcher with the institute, recognized the benchmark status the organization’s Urban Mobility Report has gained when he characterized it as “ the second slide” in many transportation presentations, coming right after the title page.
With such an important role to play, the report has developed its share of critics. They question its methodology and conclusions about where we stand and what we should do next.
The debate reflects a fundamental issue for commuters: When we try to measure our commuting misery by the numbers, what values should we look at and what goals should they reflect?
Urban Mobility Report
The latest version, released last week, continued a depressing trend for the D.C. region. By any of the various measures of mobility, we don’t have it. In fact, our congestion and delays are among the worst for very large urban areas, based on the 2009 statistics. Here’s a summary of our key nationwide rankings. Travel Time Index: No. 2 This measure of congestion focuses on each trip and each mile of travel. It is a ratio of travel time in peak periods to travel time in free-flowing traffic.
Delay per peak auto commuter: No. 1
This is a yearly sum of delays for people who drive in the peak periods of 6 a.m. to 10 a.m. and 3 p.m. to 7 p.m. It illustrates the effect of per-mile congestion as well as the length of each trip, the report says. We tied with Chicago.
Delay per non-peak traveler: No. 2
This measure reflects annual extra travel time for people during midday, evening and weekends.
Congestion cost per peak commuter: No. 2
This is the value of travel delay for 2009, estimated at $16.01 per hour for a person’s travel, and the excess fuel consumption, estimated using a state’s average cost per gallon.
Excess fuel consumed per commuter: No. 1
This is a measure of increased fuel consumed during travel in congestion rather than in freeflowing traffic.
In many of the key measures dating from 1982, such as the Travel Time Index and the delay per peak auto commuter, we’ve moved up in the rankings.
“You have been one of the leaders,” Lomax said of the D.C. region’s commuters.
How do these misery rankings help us?
Lomax said, “Folks would like to know how bad things are in relation to other people — more importantly, how bad they are relative to where they’ve been — so they can make decisions about public expenditures of funds.”
For the average commuter, there’s something missing in such analyses: What about me? The measure of delays for non-peak travelers might in part reflect the severity of the lunchtime traffic in Tysons Corner, but the measures don’t reach such specific levels for Tysons or any other area.
“What we’re reporting are regional averages,” Lomax said. “ The average is just the average. It’s not about any individual.”
But he said the report still could serve to raise the consciousness of a commuter, who might focus on the cost of traveling at peak hours and ask whether it would make sense to leave 15 minutes early or to spend more time working from home.
The critics’ case
CEOs for Cities, a national group whose goal is to discover ways that urban areas can bemore successful economically, released a study last fall called “ Driven Apart.” Focusing on the mobility report’s Travel Time Index, it faulted the transportation institute for missing the role that increasing travel distances and sprawl have played in the amount of time we spend commuting.
Over the history of the mobility report, many commuters have moved farther from where they want to get to each day. “ That increase in distance was enough to explain the increase in travel time,” said Joseph Cortright, the study’s author.
A reexamination of the traffic data in that light shows that commuters’ experience nationwide has not been universally bleak, he said. “In some cities, we’ve seen total travel times at peak hours actually decrease, because people are now driving shorter distances.” He pointed to Portland, Ore., as one example. Even the D.C. region dropped from second to 14th place on peak travel time in this reworking of the data from the previous mobility report.
As with the mobility reports, the data Cortright used do not quantify how miserable you are on Interstate 66 at the Capital Beltway in the morning or on the inner loop through Bethesda in the afternoon. But they suggest something individuals can consider: The effect on their travel lives of being closer to work and in a community that offers options that include transit riding and walking.
For policymakers, Cortright suggests, the study asks whether their goal should be to increase road capacity for the sake of increasing peak-period speeds, or instead to concentrate on landuse plans that don’t segregate home, office, commerce and entertainment into widely separated zones reachable only by cars.
I asked readers of the Dr. Gridlock blog to tell me how they measure the misery of commuting. These themes emerged:
Total time spent in the car isn’t as important as stress factors, such as the unpredictable behavior of pedestrians, cyclists and drivers.
It’s difficult to measure individual misery because commuters have different tolerances, based in part on their ages and experiences with different travel patterns and travel modes.
Peoplemake choices that are difficult to quantify. For some, the misery of a long commute is offset by the pleasure of hearing birds singing when they get home.
An overall measure doesn’t reflect the reality that some days and some routes are better than others.
Ronald F. Kirby, transportation planning director for the Metropolitan Washington Council of Governments, said this about the big studies of commuting experience: “ They are averages, based on a typical day — if there ever is such a thing. If you look at the individual commuters and what they think about in terms of what’s involved in getting to work, there’s an enormous variation in their concerns.”
For example: Will my commuting time be the same today as it was yesterday?
“ That’s terribly important,” Kirby said. “It’s the reliability that really bothers people on the road and increasingly on the Metro. That’s not picked up in any of these data, but that’s what’s really important to people.”
Gridlock in Chicago, which, one statistical measure says, is tied with the District for worst congestion.