Seattle moves $7B light rail project to design phase

Sound Transit, Seattle’s public transit authority, has selected a designer for the West Seattle Link Extension (WSLE) project, officially moving into the design phase for the up to $7.1 billion initiative. Construction is expected to begin in 2027.

The WSLE will be a light rail transit system linking several neighborhoods in the city. The project covers a 4.1-mile corridor with four new stations providing service to SODO, Delridge, Avalon and the Alaska Junction. The completed system will consist of a series of elevated tunnels and surface routes.

Sound Transit breaks the project down into four segments – SODO, Duwamish, Delridge and West Seattle Junction. The SODO segment will consist of a new line running parallel to the existing Link light rail line in the SODO Busway. The guideway’s height will consist of being at-grade, a retained-cut and approximately 20 feet high along sections of the line. The project will also add new station platforms with a staggered station configuration.

The Duwamish segment will continue following the existing light rail line on an elevated guideway. It will be built across an existing fixed, light-rail-only bridge over the West Waterway. This portion of the line will connect with an at-grade operations and maintenance facility.

The Delridge portion of the project will transition between elevated and at-grade guideway. Notably, this portion of the project calls for roadway improvements to facilitate travel. The city will develop improvements to an intersection, enhancing vehicular access and pedestrian crossings into the Delridge Station area. The city will also reconfigured nearby streets to provide buses with a dedicated circulation pathway.

The West Seattle Junction segment will start in a retained cut before transitioning into a tunnel. This portion of the project will include the Avalon and Southwest Alaska Stations. The Avalon Station will be in a lidded retained cut with entrances on either side of 35th Avenue Southwest.

The Alaska Junction Station will be inside a tunnel underneath the roadway with entrances on either side of Southwest Alaska Street.

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