Traffic congestion easing, study says

By Eric Pryne
Seattle Times staff reporter

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The nation's best-known, most widely publicized ongoing congestion study suggests traffic on Seattle-area roads actually is better now than it was a decade ago.

The Texas Transportation Institute's (TTI) 2004 Urban Mobility Report, released yesterday, says the average Seattle rush-hour traveler spent 46 hours stuck in traffic in 2002, the most-recent year for which information is available.

That's down 27 percent from 1992, the report says, when the average annual delay was 63 hours.

Likewise, it adds, the region's "travel time index" — a measure of how much more slowly traffic moves during peak periods than during other times — dropped from 1.38 to 1.35 during those 10 years. That means the typical 2002 peak-period trip took 35 percent longer than during non-peak times, when roads are free-flowing.

Seattle's improvement in the study's two most commonly cited measures of congestion contrasts sharply with traffic trends in most of the 84 other metropolitan areas included in the report.

Just seven others experienced declines in annual delay per traveler between 1992 and 2002. The travel-time index dropped in just one other city: Honolulu.

Tim Lomax, a TTI research engineer who co-authored the report, said the data indicate that much of Seattle's apparent improvement can be attributed to more widespread freeway-ramp metering, more-aggressive response to accidents, and other changes in how roads are managed. The region is among the national leaders in such innovations, he said.

The downturn in the local economy in recent years probably is another factor, Lomax added.

TTI arrives at its conclusions not by observing traffic, but by analyzing databases. Some Seattle-area commuters said TTI's findings don't jibe with their experience on the road.

"The 405 corridor seems a little better," said Tony Ting of Sammamish, "but other places are worse, especially way farther out of the city."

Ting commutes 9-1/2 miles to Microsoft's Redmond campus. It's much worse now than when he first began driving it eight years ago, he said; on a bad day, it can take 55 minutes.

"I find it unbelievable that traffic is any better," said Barbara Brown of West Seattle, an information-technology project manager whose work takes her all over the region.

For awhile, she said, she had to drive to Bothell every day. The trip took an hour on a good day, up to two hours on a bad one.

Linda Mullen, spokeswoman for the state Department of Transportation, said changes in TTI's methodology may be partly responsible for the reported improvement in Seattle-area traffic.

But congestion probably has eased a little over the past few years, she said, in part because of the economy, in part because of the agency's beefed-up highway incident-response program.

Mark Hallenbeck, director of the Washington State Transportation Center at the University of Washington, said he hasn't yet examined TTI's work. He said he senses subjectively that traffic is a little worse now than it was in 1992.

"But there are some corridors where traffic has gotten better," he added, including the westbound morning and eastbound evening commutes across Lake Washington on Highway 520 and the southbound afternoon commute on Interstate 5 from Seattle to Des Moines.

Just three years ago TTI ranked Seattle's travel-time index second-worst in the nation, a dubious distinction that civic leaders cited frequently in calling for more transportation investments.

Since then the region's national ranking in TTI's annual reports has dropped steadily — to fifth in 2002, 12th in 2003 and 17th this year.

Los Angeles tops the list this year. Portland is 14th, Spokane 74th.

Seattle's improvement coincided with changes in the way TTI measured traffic. After critics, including environmentalists and Washington's Department of Transportation, challenged the reports' accuracy, the institute last year revamped its calculations.

For the first time, it plugged in the effects of public transit, ramp meters and other so-called "operational" improvements on congestion. That pleased the state transportation department, which had earlier withdrawn its financial support for TTI in protest. Funding was restored this year, spokeswoman Mullen said.

The changes helped Seattle's national ranking. Even so, the 2004 report indicates, traffic still is a serious problem here.

Despite the declines since 1992, the region's travel-time index and annual delay per traveler still are higher than those of most other metropolitan areas with 1 million to 3 million people, it concludes.

TTI is a branch of Texas A&M University. It included Tacoma and Everett in evaluating Seattle's traffic.

The foundation of TTI's annual report is a Federal Highway Administration database that contains such information as miles and lanes of freeway and arterials in each city, and the average daily traffic volumes on each road segment.

TTI applies assumptions and estimates to that data to arrive at its conclusions.

The TTI report suggests that Seattle has benefited more than most other cities from public transit and "operational treatments": ramp meters, freeway incident-response programs, traffic-signal coordination and arterial access-management strategies such as acceleration and deceleration lanes.

Operational treatments saved each rush-hour traveler another five hours, it adds.

Nationally, the report says, total hours of delay increased fivefold between 1982 and 2002. The solution to congestion lies in a variety of approaches, it adds: building more roads and transit, using those that are already built more efficiently, managing demand to avoid peak-period traffic, and designing development that is less auto-dependent.

But "realistic expectations are also part of the solution," TTI says. "Large cities will be congested."

That's an important conclusion, Mullen said: "The best you can do is manage it. You can't solve it."

Eric Pryne: 206-464-2231 or epryne@seattletimes.com

Copyright © 2004 The Seattle Times Company

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