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.

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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 free-flowing 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.