How commuters define misery
The Texas Transportation Institute on Thursday is scheduled to release the latest version of the report we've long relied on as a benchmark of our misery as commuters. The D.C. region is always high up on the list of congested areas in the institute's Urban Mobility Report.
The report released in 2009 again ranked Washington second to Los Angeles in car congestion. Politicians, transportation advocates, reporters, columnists and commuters cite the statistic whenever they seek a national measure of just how dire a fix we're in.
But what does it mean? It's not your personal misery index as a commuter. That depends more on the day, the season and the route. Do you have to switch from car to train, train to train or bus to bus? Is your route under construction? Do you have a long and straightforward trip, or do you drive fewer miles and need to make many lane changes in heavy traffic to follow a route that involves different roadways?
The report doesn't drill down that far. Among the nation's largest urban areas, we ranked second in the 2009 report behind Los Angeles in annual hours of delay per traveler. That's the hours of extra travel time divided by the number of peak period travelers.
We ranked fourth on the Travel Time Index, a ratio of the travel time during the peak period to the time required to make the same trip at free-flow speeds. We ranked second, again behind L.A., in wasted fuel per traveler.
So what help is it to know that? The report says this about the measures and rankings: "They are especially good at identifying multi-year trends and in comparing relative
levels of congestion. As evidenced by the continual refinement of the measures, estimation procedures and data, however, this series of reports is still a 'work-in-progress.' "
For example, all the estimation procedures involve simplifying assumptions that are not correct for every situation.
The institute's measures continue to evolve. The latest report is going to combine historical traffic speed data provided by INRIX with traffic counts provided by public agencies to produce the latest congestion trends. INRIX is a private provider of traffic information and services.
Also, the congestion analysis won't be just for peak periods. Because of the additional data from INRIX, it can include off-peak and weekend congestion as well.
In a preview released in September, the institute described the new national data report this way:
1. Speeds on many congested sections of road are not as bad as previously estimated. There are severe bottlenecks with very low speeds, but most sections are not congested for more than four to five hours each day.
2. The true effects of incidents are not as significant as previously estimated. When crashes occur, congestion increases, but in most cases not as much as previous estimates. The bottleneck delay that crashes cause is partially offset by free-flowing traffic once the crash scene has been passed.
3. Off-peak direction delay is not a significant problem on most roads. High daily traffic volumes were previously estimated to create travel delay in the "minor" direction. The real speeds indicate the congested time may be only half as much as previously estimated.
The report won't help you pick where to live or by what means to travel. But it means a lot to transportation officials and advocates who want to make travel easier in congested areas. And some of the adjustments highlighted in the preview may lead us all to think differently about just how badly off we are and why.
The writers of the study don't advocate any particular fix:
"Solutions to the congestion problem will not change; the Urban Mobility Report analysis indicates that many strategies are needed in most urban regions. No single strategy has been successful in addressing mobility problems over the long-term."
But another group, CEOs for Cities, released a report funded by the Rockefeller Foundation that challenges some of the assumptions, methodologies and results from previous mobility studies by the Texas Transportation Institute.
See if you think this approach gets closer to the realities of urban travel.
The study, called Driven Apart, says previous Urban Mobility Reports are unreliable guides to understanding the nature and extent of transportation problems in the nation's metropolitan areas. For example, the Mobility Report's Travel Time Index is structured so that it conceals the effect of sprawl and travel distance on travel time.
As long as travel volume increases more than capacity, the model predicts slower speeds and travel times.
But a driver cares about how long the entire commute is, not just about how long the driver spends in congestion, Therefore, sprawl counts, the study says. Many regions have land-use policies and transportation programs that wind up putting a great distance between people and their destinations.
If you promote the value of travel distance and reexamine the data, as the Driven Apart study did, the D.C. area doesn't even make the top 10 in travel misery. Taking the place of Los Angeles, Washington and Atlanta as home to the most miserable commuters are Richmond, Raleigh-Durham, Detroit and Kansas City.
The key reason is the much longer-than-average peak period travel distances in those cities, Driven Apart says.
What does this mean for transportation policy? Seek solutions in better land use, not just in road capacity. The study concludes that the "secret to reducing the amount of time Americans spend in peak hour traffic has more to do with how we build our cities than how we build our roads."
How do you define commuting misery? Post a comment below.
| January 19, 2011; 1:35 PM ET
Categories: Commuting, Congestion, Driving, Transit | Tags: Dr. Gridlock
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