Sound Transit’s new cost estimate for the West Seattle Link Extension is set between $6.7 billion and $7.1 billion. The project’s final Environmental Impact Statement from September previously estimated the project to cost between $5.1 billion and $5.6 billion, 27% less than the new projection of the maximum estimated $7.1 billion price tag.

Officials said they underestimated costs, which accounts for the price increase. 

Due to the increased cost projections, the Sound Transit Board of Directors passed a motion directing the agency to create a plan that includes financial and project-level measures to improve its financial situation and move the project through design. 

The new cost estimates came alongside the agency moving forward in the West Seattle Link Extension project, as the Sound Transit Board of Directors approved select routes and stations on Thursday.

The selected West Seattle Link Extension routes and stations include a station on 41st Avenue in the West Seattle junction; one on Andover Street in the Delridge segment; a South Crossing alternative in the Duwamish segmental; and an at-grade lander access station in the SODO segment.

The selected alignment incorporates refinements requested by the Sound Transit board when it identified the preferred alternative in 2022. 

“Through the board-directed work plan, our action today allows Sound Transit to use the design process to address cost pressures, reduce impacts, and prepare projects for construction, fulfilling our promise to the voters,” King County Executive and Sound Transit Board Chair Dow Constantine said in a statement.

The project will extend the light rail by approximately four miles and serve four new stations in the SODO, Delridge, and West Seattle neighborhoods.

Construction is expected to begin in 2027.