Alaskan Way Viaduct options expand to 10

Just a year ago, Seattle voters were casting ballots on whether the Alaskan Way Viaduct should be replaced by a tunnel or another aerial bridge.

What a difference a year makes.

Seattle voters rejected both options and today the state is juggling 10 options — what it calls "families" — to replace the one-mile stretch of the viaduct along Seattle's central waterfront.

The 10 options include three tunnels, three surface plans and four aerial proposals.

The state has convened a group of 30 "stakeholders," who have been meeting to reach some consensus on what a new viaduct or other options should look like.

The state hopes to narrow the options to a handful by August and make a recommendation by Dec. 1. Gov. Christine Gregoire is scheduled to choose one by the end of the year.

Back on the table are both a retrofit of the existing viaduct and building an Elliott Bay bridge, a high bridge that would cross the water. The state Department of Transportation had already dismissed both of those ideas.

Another idea is to build a partially covered viaduct that would be flanked by businesses and would have a park on the roof.

Also in the mix is a deep-bore tunnel, with traffic going in one direction under Western Avenue and in the other direction under First Avenue.

Three surface alternatives also are under consideration, but still in the mix is whether it should be four, six or eight lanes.

The three surface alternatives:

• A boulevard such as the existing one on Alaskan Way.

• A system where Alaskan Way would carry traffic in one direction and Western Avenue would carry traffic in the opposite direction.

• An Alaskan Way expressway, in which there would be fewer stoplights and there would be four northbound lanes and three southbound lanes.

Then there is a proposal to rebuild the viaduct, either as a stacked roadway as it is today or a single-level, side-by-side road for northbound and southbound traffic with four lanes.

One tunnel idea is what engineers call a "depressed roadway," where the road would be below ground with an intermittent lid covering it.

There are no price tags on any of the alternatives.

"This is our attempt to lay on the table everything we can do on the Highway 99 corridor," said project manager Ron Paananen, adding that whatever choice the state makes will require another environmental-impact statement.

The state already has spent $21 million on an environmental study for a viaduct replacement. While that study is technically dead, Paananen said information contained in it still can be used in a new document.

The state already is working on shoring up viaduct columns and replacing the noncontroversial south end of the viaduct. Taking down and replacing the southern end of the viaduct is scheduled to start in fall 2009.

State engineers have been walking around with Legos pieces in their pockets, which they assemble to see what a viaduct replacement might look like.

Because most options will affect traffic on Interstate 5, the state will be looking at how to better manage the freeway, including the possibility of closing some of I-5 entrances and exits, such as Yale and Union streets.

Or creating a northbound transit-only shoulder during peak hours from Olive Way to Highway 520.

Other options would be to require three passengers in a car to use the HOV lanes, that some lanes be tolled, and that a northbound lane be added between Seneca Street and Highway 520.

Other ideas under consideration include:

• Creating a two-way Mercer Street. This has long been on the list of city improvements, and was part of a failed bond package last November. The Mercer improvement could be part of the viaduct funding package.

• Lanes could be added to Second and Fourth avenues, by removing parking. First Avenue South would have two lanes in each direction and there would be a two-way Eighth Avenue connection to existing I-5 overpasses.

• Third Avenue would be restricted to transit-only all day (now it's restricted only during rush hour), while Second and Fourth avenues would be transit only during peak periods. Fourth Avenue South would have transit-only lanes.

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