Benefits of closing viaduct studied

By Susan Gilmore
Seattle Times staff reporter

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But traffic would be a mess.

Those are the findings in a new report to be released today by the Washington State Department of Transportation (DOT).

The state says closing the viaduct during construction could save time and money but would create gridlock through downtown Seattle. A closed viaduct would add 25,000 cars to Interstate 5 downtown each day by 2010, an 8 percent increase, and 33,000 cars to downtown streets, a 36 percent increase. The viaduct now carries 110,000 vehicles a day.

Where there are now two hours of congestion each day on downtown streets and five hours on Interstate 5, closing the viaduct during construction would mean 11 hours of congestion daily downtown and 14 hours on I-5 by 2010.

"Can we take the grief?" said Maureen Sullivan, urban-project director for the DOT. "What we want to tell people is this would save time and money, but look at what happens to the traffic."

The study was prompted by a group of Seattle waterfront business owners, who complained that closing the viaduct during construction wasn't considered in the 168-page environmental-impact statement written for the five new viaduct options.

They said closing the viaduct could shorten construction time and save money.

Linda Mullen, DOT spokeswoman, said the consultants who wrote the environmental statement didn't look at closing down the viaduct "because the original guiding principle was to maintain traffic." It envisioned a partial viaduct closure, which would maintain two lanes of traffic in each direction on the viaduct or on a detour route.

The business owners said they like the tunnel alternative because it has more benefits and fewer adverse effects than other alternatives. But the high cost — at an estimated $3.4 billion to $4 billion, the highest of the five alternatives — could be prohibitive.

They said closing the road could save money and "may well reduce the cost of the tunnel alternative enough to make it affordable."

DOT this week announced it essentially had narrowed the options for a new viaduct to a tunnel or rebuilding the existing structure. The three other options are still on the table, but they are unlikely choices.

The tunnel would take from seven to nine years to build. Rebuilding the viaduct would cost $2.7 billion to $3.1 billion, and construction would take six to eight years.

Sullivan said what the new study points out is that there is no room for the cars from a closed viaduct.

"It would be a pretty miserable thing to do, and I don't know why people would support it considering what it would do to traffic," Sullivan said, adding that today there is only 12 percent to 15 percent capacity left on downtown streets.

The report also envisioned that up to 62 percent of commuters to downtown Seattle might be using transit by 2010, which could help reduce the impact of viaduct construction.

Susan Gilmore: 206-464-2054 or sgilmore@seattletimes.com

Copyright © 2004 The Seattle Times Company

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