The 28 to 40 percent cost increase could lead to delays in the light rail to West Seattle or force cost-cutting measures.

The cost of extending light rail to West Seattle is expected to be $1.1 billion to $1.6 billion higher than previous estimates, according to newly released information from Sound Transit. The updated cost ranges provided in the Final Environmental Impact Statement (FEIS) for the West Seattle Link Extension suggest Sound Transit’s board will have to make difficult decisions in the coming months as it sets a final direction for the project.

Sound Transit had previously estimated the cost of West Seattle Link at just under $4 billion, but the new estimates for the preferred route chosen by the board in 2022 represent a potential increase of 28 to 40 percent, well above inflation. The FEIS notes that these increased costs could disrupt Sound Transit’s overall delivery schedule, which currently calls for West Seattle Link to open by the end of 2032.

“(B)ased on current cost estimates and revenue projections, the preferred alternatives and design options for the West Seattle Link Extension are expected to exceed the assumptions in Sound Transit’s Realigned Financial Plan,” Sound Transit wrote in the FEIS.

The cost increases affect all sections of the four-station light rail project, which includes a new bridge over the Duwamish River next to the West Seattle Bridge. That river crossing, estimated at $1.2 billion to $1.3 billion in Sound Transit’s 2022 environmental impact statement, is now expected to cost $1.9 billion to $2.15 billion. And a tunnel under 41st Avenue SW, the Sound Transit board’s preferred option to get to Alaska Junction, is now expected to cost $1.75 billion to $1.9 billion, up from $1.1 billion.

Cost overruns on “megaprojects” aren’t unique to Sound Transit. The first leg of LA Metro’s Westside Subway, which includes three new stations, has seen over 20% total cost increases since construction began in 2014, adding $575 million to the project’s cost. Locally, the Washington State Department of Transportation was left sweating last year when bids for the final leg of the SR 520 bridge replacement project in Portage Bay came in nearly 70% higher than originally estimated, forcing lawmakers to search for a way forward.

When Sound Transit fails to reduce costs, the company’s usual recourse is to delay projects to seek higher revenues – a troubling prospect given the already long timelines of the Sound Transit 3 projects.

A 30 to 40 percent cost increase is alarming for West Seattle Link, but it is even more so for the $11.2 billion Ballard Link Extension project, which was originally intended to connect to West Seattle but is now undergoing an environmental review on its own schedule. If Ballard Link costs increase by the same amount, that would represent a budget increase of $3 to $4.5 billion.

Sound Transit has still not released the second draft of the Ballard Link environmental impact study after the board added additional options for the placement of the South Downtown, South Lake Union and Uptown stations, rendering the first draft of the environmental impact study inadequate. These delays mean the agency does not expect to complete the FEIS for Ballard Link before 2026.

The biggest opportunity to reduce costs for West Seattle, among the options considered by FEIS, is to reconsider the tunnel to Alaska Junction. An elevated line over Fauntleroy Way SW could save Sound Transit between $600 million and $850 million. Transit agencies around the world have found that underground lines are significantly more expensive to build than elevated lines, leading some transit experts to question Sound Transit’s earlier claims that there was little cost difference between the options. It turns out that rule of thumb was correct.

As previously discussed in a cost-cutting study, the agency could also eliminate the planned Avalon Way station, but if a tunnel is planned anyway, that would likely save only $250 million to $500 million. While ridership estimates are not very different between the options, the increased Fauntleroy Way option is actually expected to attract the most riders, 8,000 daily compared to 7,500 for a tunnel without an Avalon station.

When the decision was made, it was said that the tunnel option was affordable under the agency’s financial model, after it had initially appeared that Seattle could only build the West Seattle Light Rail underground if it was funded with city funds. The elevated options, which included the planned acquisition of numerous properties — including some brand-new apartment buildings — came with high cost estimates, given the constraints Sound Transit faces in trying to build stations in the Fauntleroy Way right-of-way.

The West Seattle Link project has already been heavily criticized for the planned relocation of businesses near Delridge Station, and the tunnel seemed like a way to avoid further such impacts. The idea of ​​building an elevated train above the street through the heart of West Seattle’s main artery and business district is also likely to face stiff opposition.

While the board can now deviate from its preferred option, the cost of a delay is also a factor. Switching to the elevated tunnel option would also incur costs as inflation eats into the project’s budget while Sound Transit conducts additional environmental reviews. But compared to Ballard Link, where a 10-month delay would likely cost $500 million, the cost of a delay in West Seattle is likely to be less given the smaller scope of the project.

Sound Transit’s board has not yet been briefed on these potential impacts of West Seattle Link’s cost increases, but is expected to do so later this month. But this week, the board’s System Expansion Committee received a briefing from its Technical Advisory Group (TAG), the panel of experts created to address the significant challenges Sound Transit faces in implementing these megaprojects. TAG praised the board for sticking with its preferred alternative in South Lake Union, but cautioned that more obstacles along the way are soon to be expected.

“Costs are going up across the country, folks, you just have to stay on top of things and keep trying to find solutions to all the problems that come your way,” Grace Crunican, former BART general manager and TAG co-chair, told board members. “And time is not your friend, so pull yourself together, grit your teeth and make those tough decisions.”

correction: The earlier draft said the cost estimate for the upper end had increased by $1.5 billion. In fact, the increase was $1.6 billion.

Ryan Packer lives in the Summit Slope neighborhood of Capitol Hill and has been writing The Urbanist since 2015. They report on multimodal transportation issues, #VisionZero, historic preservation, and local politics. They believe in using Seattle’s history to create the vibrant, diverse city we all want to live in. Ryan’s articles have appeared in Capitol Hill Seattle Blog, Bicycle PortlandAnd Seattle Bike Blogwhere she also worked as a temporary editor for four months.