State proposes 8 Alaskan Way Viaduct alternatives

Plans to replace the Alaskan Way Viaduct continue to inch forward with the state Department of Transportation releasing eight finalists for a new roadway through the central Seattle waterfront.

Gone are plans to retrofit the viaduct or build an Alaskan Way expressway or a bridge over Elliott Bay.

What remains are three surface-boulevard, two aerial-viaduct and three tunnel options. None of the proposals has cost estimates. Those may be done this fall, when the DOT hopes to narrow the choices to two or three. Gov. Christine Gregoire plans to announce the winner in December, which could be a hybrid of the eight proposals.

Taking down and replacing the southern end of the viaduct is scheduled to start in fall 2009.

Costs could eliminate some of the plans. While the state had $2.8 billion available to rebuild the viaduct, it has already spend a large amount of that money on work stabilizing the south part of the viaduct, and DOT officials said only about $1.5 billion remains.

The eight proposals, released Thursday, include:

• A four-lane boulevard along Alaskan Way, complete with stoplights and improvements to Interstate 5. One proposal is to convert the southbound HOV lane between Denny Way and Spokane Street to a HOT (high-occupancy/toll) lane where drivers would pay to use it. This plan also calls for a new transit-only lane northbound from Olive Way to the Highway 520 exit, as well as improved transit.

• A four-lane boulevard along Alaskan Way, but with more transit and improvements to downtown surface streets. It would also try to squeeze one extra lane on I-5 northbound between Cherry Streets and the Highway 520 exit by narrowing the lanes. This option would create about 80 feet of open space along the waterfront.

• A six-lane Alaskan Way-Western Avenue couplet. The two northbound lanes would be on Western and the southbound lanes on Alaskan Way. It would create 110 feet of open space on the waterfront and envisions the same improvements to I-5 as the boulevard proposal.

• A four-lane elevated viaduct, with the lanes side by side, not stacked. This would be similar to the existing viaduct and would retain the views. It would add a northbound I-5 lane between Seneca Street and the Highway 520 exit. And it would convert the HOV lane from Mercer Street to Spokane Street to a HOT lane.

• The most unusual proposal would be a four-lane elevated viaduct that would be covered by a park, with the option of erecting buildings underneath. This viaduct would be about as high as the existing viaduct. The state envisions selling development rights below the viaduct to help with the cost of the structure.

• A four-lane bored bypass tunnel that would start near Qwest Field and go under Western Avenue and Post Alley. The only offramp would be at King Street. This tunnel would be 100 feet deep in places and would go under the Burlington-Northern railroad tracks. It would also go under the Battery Street Tunnel.

• A cut-and-cover tunnel along the central waterfront. It would be four lanes and emerge onto an elevated roadway at Stewart Street and a surface street by the Pike Place Market. It also calls for the I-5 HOT lane.

• A four-lane lidded trench, with two lanes in each direction. There would be openings in the cover to ventilate the roadway. It also calls for signals on streets north of the Battery Street tunnel.

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