October 28, 2024

Sound Transit finalizes West Seattle Link route, eyes 2027 construction start

Photo by Han Zheng [enlarge]

The light-rail extension would connect riders between SoDo and the Alaska Junction. A segment of the line at Mount Baker Station is pictured.

The Sound Transit Board has finalized the route and station locations for the authority's planned West Seattle Link Extension.

The West Seattle Link Extension (which is also known as the 3 Line) was approved by voters in 2016. The project would extend Sound Transit's Link light rail network by 4.1 miles and includes four new stations plus a new elevated light-rail only bridge over the Duwamish Waterway, running parallel to the West Seattle Bridge.

With the route and stations now selected, the project is approved to move forward into the final design phase. Construction is anticipated to begin in 2027, and Sound Transit hopes to start service in 2032. Sound Transit has been working with HNTB on the design thus far. The line would be divided into four segments: the SoDo, Duwamish, Delridge, and West Seattle Junction segments. The SoDo and Delridge segments would each have one station. The West Seattle Junction segment would have the remaining two.

In SoDo would be a new at-grade station and a second set of at-grade tracks near South Lander Street. The SoDo and Delridge segments would be connected across the Duwamish waterway by the Duwamish segment, which would comprise the new high bridge, to be located on the south side of the West Seattle Bridge.

Sound Transit image [enlarge]

The finalized route includes a new elevated light-rail only bridge over the Duwamish Waterway. This conceptual rendering imagines what that might look like.

The Seattle Design Commission this summer got a glimpse of what that new bridge could look like. Project renderings — not a final design — depict a two-tower, 1,690-foot-long cable-stayed bridge with diamond-shaped pylons. The towers would both be about 374 feet in height, with the main span between them extending some 953 feet. Trains would, at their highest point, run about 140 feet above the waterway.

The finalized route places the Delridge segment station near Southwest Andover Street. That would be an aerial station. From there, the line would continue to the West Seattle Junction segment that will include a slightly below-grade station (the Avalon station) near 35th Avenue South and Fauntleroy Way Southwest and would pass through a medium-length tunnel along 41st Avenue Southwest before terminating at an underground station beneath Alaska Junction.

The final route and station alignment were selected by the board last week. The alignment was previously identified as the preferred alternative in the project's final environmental impact statement (EIS), which was published in September.

In a press release, Sound Transit said the final alignment incorporates refinements that the board previously requested to improve station access and minimize displacements of organizations serving low-income and communities of color.

Map courtesy of Sound Transit [enlarge]

The new line would have four segments with four new stations.

The board's recent approval of the route also establishes the project definition for the NEPA Record of Decision (ROD). When the ROD is issued, the federal environmental review process will be complete, and the project can proceed. This milestone is expected in late 2024.

The West Seattle Link Extension is now expected to cost between $6.7 billion and $7.1 billion. That's a sharp increase from the $4 billion price tag that was announced in 2023.

To account for this uptick, Sound Transit said it is looking for “financial opportunities” to help fund the project and has passed a motion that directs the agency to develop a workplan to improve the agency's financial situation and move the project through design “to inform a financially sound project to be baselined.” This workplan will include programmatic, financial and project-level measures. The motion outlines several potential money sources that include federal loans, strategic property acquisitions and grant revenues.

Sound Transit Board Chair and King County Executive Dow Constantine said the board-directed work plan will allow “Sound Transit to use the design process to address cost pressures, reduce impacts, and prepare the project for construction,” fulfilling a promise to voters to build the line.

Related Stories:

• Behold! Sound Transit shows ‘diamond pylon' span over Duwamish  08-19-2024