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Tuesday, July 25, 2006 - Page updated at 11:07 AM


What will happen if viaduct closes? Study takes a look

Seattle Times staff reporter

If the Alaskan Way Viaduct is closed for 3- years to be replaced with a tunnel or a new elevated structure, 48,000 cars that regularly drive the viaduct each day will be diverted to city streets and 20,000 more will move to Interstate 5.

Those figures are included in a new supplemental environmental-impact statement on the viaduct released Monday. The 134-page document cost $4 million to produce.

"This is a milestone for the project," said Ron Paananen, the viaduct-project manager for the state Department of Transportation.

In detailing expected effects on traffic, the document said that under typical conditions, Highway 99 currently "is congested about one hour per day or less."

"When Highway 99 is restricted during construction," the document said, "Highway 99 is expected to have slow-moving conditions for 10 to 12 hours a day depending on lane restrictions."

Paananen said the state has committed $100 million for traffic mitigation during construction, and the city has been weighing options, including having the West Seattle water taxi run year-round.

"The biggest issue is how we will keep downtown working during construction," Paananen said. The state wants to begin utility relocation in 2008.

Read the report

The supplemental environmental-impact statement on construction during replacement of the Alaskan Way Viaduct is available at

Copies also are available at Seattle's neighborhood service centers and at Seattle Public Library's Ballard, Capitol Hill, Central, Delridge and Northeast Seattle branches.

The public has until Sept. 22 to comment on the environmental statement, and four public hearings on the document will be Sept. 7-14.

The supplemental document updates the initial environmental-impact statement for the viaduct that was released in 2004.

It differs from the original in three major ways.

• The first report laid out five alternatives for replacing the viaduct. Since then, the state has narrowed the options to two — building a tunnel or replacing the viaduct with another elevated structure, options that range in price from $2.5 billion to $4 billion.

• The initial study envisioned the viaduct remaining at least partially open during construction. The new document lays out three plans that would close the viaduct for up to 3- years. If the state chooses the shortest construction time — 6- to 7 years — the viaduct would be closed fully 3- years.

Compressing the construction schedule has been pushed by some downtown business owners who complained that closing the viaduct during construction had not been considered in the original environmental study.

• The new study gives a detailed look at lowering Aurora Avenue North north of the Battery Street tunnel. But state officials have put that idea on the back burner, focusing on what they call the "core project," replacing the viaduct and part of the Alaskan Way seawall.

Susan Gilmore: 206-464-2054 or

Copyright © 2006 The Seattle Times Company



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