New details about the Alaskan Way tunnel project indicate West Seattleites would be able to access north and south-oriented downtown streets from a King Street exit, and east-west streets from ground-level Alaskan Way.

These and other West Seattle-related details emerged during a joint meeting of the Southwest and Delridge Neighborhoods district councils last week.

Building a tunnel with its waterside wall doubling as a new seawall is the preferred alternative of the Seattle and Washington State departments of transportation.

If such a tunnel were built along the downtown waterfront, West Seattle residents would drive north on State Route 99 and take an exit to be built at South King Street. It would put motorists on Main Street in Pioneer Square. From there they could head on First, Second, Third and other north-and-south running avenues downtown, said Ron Paananen, project director of replacement of the Alaskan Way Viaduct for the Washington State Department of Transportation.

Paananen was joined at the meeting by Steve Pearce, urban design manager for the Seattle Department of Transportation.

The tunnel would be design in a stacked arrangement like the Alaskan Way Viaduct is today, except the three northbound lanes would be in the lower tube and three southbound lanes would be in the upper tube. Each tube would be about 80 feet wide.

To get to downtown streets running east and west, West Seattleites would take the King Street exit and make their way to Alaskan Way, the surface street. It will be six lanes wide south of Colman Dock and four lanes wide north of it. Alaskan Way would be equipped with traffic signals at its intersections with Yesler, Columbia, Marion, Madison and other east-west-oriented streets downtown.

Currently there are lots of parking spaces beneath the Alaskan Way Viaduct. Those would be eliminated as part of the redevelopment plan. Some curbside parking would be allowed along Alaskan Way. Planners also are considering replacing the lost sreet parking with off-site parking lots that would be served by shuttle buses to the waterfront.

Besides the tunnel idea, planners are also considering building a new, wider viaduct. However this proposal would not include rebuilding the seawall. So the deteriorating seawall would be shored up by pumping grout into the sediment around it.

Part of the complication and expense of the project is due to having to move or replace 26 different utility lines for water, sewer, electricity, gas, telephone and other needs that run along the downtown waterfront to make way for construction. In some cases, utility lines will have to be moved temporarily only to be moved again to a final location.

Utility work is expected to cost $300 million to $500 million, said Paananen.

Another considerable expense is inflation. Every month of delay for the project adds $10 million to the overall cost, he said.

The project is expected to result in no traffic moving through the downtown waterfront for three to six years, Paananen said.

A man at the meeting noted the city gave $50 million to Southeast Seattle to help the community deal with disruptions caused by construction of Sound Transit's light-rail project and noted West Seattle faces far more inconvenience with the upcoming redevelopment of the viaduct than the problems caused by laying light-rail track.

One of the first projects scheduled to be done in preparation for replacement of the Alaskan Way Viaduct will be to widen the Spokane Street Viaduct, said Dorinda Costa of the Seattle Department of Transportation. That's the elevated structure connecting the West Seattle Bridge to Interstate 5. Design is scheduled for completion this year.

Doubling the width of the viaduct is part of a package of transportation projects planned throughout Seattle proposed by Mayor Greg Nickels. It would cover the city's $500 million backlog of undone transportation projects and include money devoted to additional transportation projects 20 years into the future. The mayor's proposal goes before Seattle voters in the autumn.

During reconstruction of the downtown waterfront, First and Fourth avenues south will be dedicated transit corridors, Costa said.The city probably will ban curbside parking on those streets to add curbside lanes and maximize the streets' capacity during the long construction project.

Other preparatory work would include repaving all of the main arterial streets to downtown, Costa said. If the mayor's proposal is approved by voters, the city plans to fix all the arterial streets in Seattle. In West Seattle, that would include Fauntleroy Way, Beach Drive, California Avenue, Roxbury Street and Sylvan Way among others, said Costa.

Bridge repairs also are planned. Numerous cracks have been discovered in the West Seattle Bridge, Costa said.

Repairs are needed on the Fauntleroy Expressway, which connects the West Seattle Bridge to 35th Avenue. More work also is planned on the short bridge that carries Admiral Way over the Fairmount Ravine.

Opponents of the Alaskan Way tunnel proposal frequently compare it to Boston's infamous Big Dig. According to Paananen, replacement of the Alaskan Way Viaduct is about one-eighth the size of the Big Dig.

Tim St. Clair can be reached at tstclair@robinsonnews.com or 932-0300.