Future of the Gardiner Expressway - Nanos Research

Case StudiesReplaceAlaskan Way Viaduct, Seattle, WABackgroundThe Alaskan Way Viaduct is a 3.2 kilometer(2 mile) four-lane double-stacked elevatedhighway (two one-way lanes on each level)along Elliot Bay in downtown Seattle.Constructed in 1959, the viaduct approachesdowntown Seattle from the south. It createsa physical barrier between Seattle’s baseballand football stadiums and its port area. Theviaduct mostly serves local traffic, whichby-passes downtown on the way from Seattle’snorth and south neighborhoods. The viaductalso limits access to the Elliot Bay waterfrontfrom downtown.An earthquake in 2001 damaged thestructure’s joints and columns. Followingthe earthquake, the viaduct also settled,raising alarm that Seattle’s seawall sustaineddamage as well. It was determined after theearthquake that removing or replacing theviaduct would be more cost effective than aretrofit.Because the Washington State Department ofTransportation (WSDOT) owns the viaduct andthe City of Seattle owns the seawall, removaland replacement studies were jointly initiated.A range of alternatives – from an urbanboulevard to a cut-and-cover tunnel similar toportions of Boston’s Big Dig – were analyzed.Parking is a common use under the Viaduct.The Alaskan Way Viaduct separates downtown Seattlefrom the waterfront.Alaskan Way Viaduct Section – Before (Existing)20Future of the Gardiner Expressway