Future of Alaskan Way Viaduct Under Study Again

The 60-foot-high, 40-foot-wide, double-decked roadway that carries 107,000 vehicles a day along downtown Seattle’s western flank has been a part of the city’s waterfront for longer than most locals can remember.

As a visible and audible barrier to the waterfront, however, the Alaskan Way viaduct is hard to forget. As a result, State officials are studying ways to improve or eliminate the structure. Legislators included money for the study in the current state budget to address growing concerns about the viaduct’s stability and its effect on growth in the city’s core.Today, the state Transportation Commission will be briefed on the study’s progress. When it is completed in mid-2002, the document is supposed to show whether the span should be retrofitted, replaced or simply torn down.

Up for discussion today are several possibilities, including simply tearing down the viaduct, without replacing it, at a cost estimated at $118 million in a 1996 study; retrofitting it so it could better withstand earthquakes, at a cost of nearly $344 million; building a new, more earthquake-resistant span, for $530 million; building ramps to a new or retrofitted viaduct to link it to Mercer and Spokane streets; and finding ways to increase its traffic-handling capacity, or to re-route traffic if it is closed.

The viaduct, opened to traffic in 1953, extends more than two miles from the Battery Street Tunnel to South Holgate Street, forming one of the busiest stretches of state Route 99. The viaduct and the highway were the main north-south route through the city before Interstate 5 was built in the 1960s, and is still a favorite route for West Seattle commuters.

Calls for the viaduct’s removal have been heard many times over the years. A formal proposal was made to the state in 1995, when a group of engineers, lawyers, bankers and designers proposed a $1.4 billion plan to replace it with a tunnel. It was never accepted by the state.

A 1996 study by two University of Washington engineering professors has renewed interest in the alternative. The study found that the viaduct, built on fill, could liquefy and fall apart during a magnitude-7.5 earthquake.

Architects Lesley Bain and Dennis Haskell, who work for separate architectural companies, raised the notion again at a city design forum. The two say that removing the viaduct would free up about 9 acres of waterfront land, allowing relocation of Alaskan Way and the creation of a new pedestrian promenade at the water’s edge.

At least 6 of the 9 acres could be developed if the viaduct were removed, they say, creating new opportunities for housing.