By month’s end, the Sound Transit Board of Directors is expected to make its final decision on routing and station locations for West Seattle light rail. The first step is a vote at next Thursday’s System Expansion Committee meeting. The agenda for that meeting is out, and with it, the proposed resolution spelling out Sound Transit staff’s recommendation for the routing and station locations. The recommendation mirrors the “preferred alternative” from the Final Environmental Impact Statement – in short, the segments titled SODO 1c, DUW-1a, DEL-6b, and WSJ-5b (to find them more quickly, check the Executive Summary). The recommendation keeps all three proposed West Seattle stations (Delridge, Avalon, Junction). Here’s how the routing is described in words, without graphics, in the proposed board resolution:

The route, profile, and stations for the West Seattle Link Extension are identified in the following paragraphs (as generally described in the West Seattle Link Extension Final Environmental Impact Statement):

A. SODO Segment: The West Seattle Link Extension would begin just north of the existing SODO Station and travel at-grade west of and parallel to the existing Link light rail line replacing the SODO Busway. It would continue south at-grade under South Lander Street, which would be reconstructed as an overpass over the new and existing light rail. It would transition to an elevated guideway south of South Lander Street.

The new SODO Station would be at-grade, immediately west of the existing SODO Station. The existing at-grade pedestrian crossing of the light rail tracks at SODO Station would be closed, and a new pedestrian grade-separated crossing of both existing and new tracks would be used to access both stations. There would be a station access from the new South Lander Street bridge. Access to 4th Avenue South would occur via South Lander Street.

B. Duwamish Segment: Elevated route would continue along the west side of the existing light rail line, south from South Forest Street; continuing southwest to cross over to the south side of the Spokane Street Bridge and the West Seattle Bridge. The guideway would continue west and to the south side of the West Seattle Bridge, crossing over the Duwamish Waterway and Harbor Island on a new high-level fixed bridge. The height of the bridge could be adjusted through coordination with the United States Coast Guard. The guideway would then cross the northern edge of Pigeon Point in a combination of elevated guideway and retained cut-and-fill; turning southwest on an elevated structure that follows Delridge Way Southwest.

C. Delridge Segment: Elevated route would continue along the west side of Delridge Way Southwest, north of Southwest Andover Street. The elevated guideway would travel west along the north side of Southwest Yancy Street then cross Southwest Avalon Way, transitioning from elevated to at-grade in the vicinity of 32nd Avenue Southwest. The guideway would turn south to travel south along the east side of the West Seattle Bridge connection to Fauntleroy Way Southwest and transition into a retained cut.

The Delridge Station would be elevated north of Southwest Andover Street and west of Delridge Way Southwest in a northeast-southwest orientation.

D. West Seattle Junction Segment: Tunnel route would begin in a retained cut south of Southwest Yancy Street and follows the east side of the West Seattle Bridge/Fauntleroy Way Southwest to Southwest Genesee Street, entering into a tunnel at Southwest Genesee Street and 37th Avenue Southwest and curving southwest west of 37th Avenue Southwest to 41st Avenue Southwest to terminate at Southwest Hudson Street, with tail track in a north-south orientation under 41st Avenue Southwest. Preferred Option WSJ-5b is a refinement of Alternative WSJ-5 analyzed in the Draft EIS, and it was refined based on the Sound Transit Board’s direction to explore an option to shift a station entrance to 42nd Avenue Southwest at the Alaska Junction Station to improve access to the Alaska Junction.

The Avalon Station would be in a lidded retained cut south of Southwest Genesee Street, beneath 35th Avenue Southwest.

The Alaska Junction Station would be in a tunnel beneath 41st Avenue Southwest and Southwest Alaska Street. Station entrances would be on either side of Southwest Alaska Street. The entrance south of Southwest Alaska Street would be on the west side of 41st Avenue Southwest. The entrance north of Southwest Alaska Street would be on the east side of 41st Avenue Southwest.

The System Expansion Committee could vote on this resolution as-is, or could decide to amend it. Their meeting is scheduled to start at 1:30 pm Thursday (October 10) in the Santa Fe Room at Union Station downtown (401 S. Jackson); the meeting will also be streamed, as explained on the agenda, which also has information on how to comment. The next major step after this meeting is expected when the full board meets two weeks later.

ABOUT THE COST: As reported when the Final Environmental Impact Statement was published, the West Seattle extension’s cost projection has swollen, potentially past $7 billion. The decision on routing and station locations does not include an allotment of construction money; it moves the project further down the design road, which is expected to take three more years. Past the midway point in design is usually when a “baseline” budget will be set and approved, for example. At last month’s meeting, board members passed this motion “directing the (CEO) to develop a workplan on measures the agency will pursue to address rising project costs and inform future baselining decisions.”