Cost estimates for extending Sound Transit light rail to both Ballard and West Seattle have risen by about $5 billion — more than 50% — the agency’s deputy CEO told agency board members on Thursday.

The cost of building light rail between Federal Way and the Tacoma Dome and of constructing a maintenance facility planned in South King County have also increased dramatically, Sound Transit said.

“While these numbers are sobering, they’re not catastrophic,” said Sound Transit CEO Peter Rogoff. He sought to assure board members that the agency has time to control the scope of projects and build in phases as money becomes available.

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Sound Transit blames the higher costs primarily on rising real estate prices in densely developed areas where projects would be built, and a hot construction market that has pushed prices higher than expected — even during the pandemic.

For the West Seattle and Ballard light rail lines, more than half of the increase is due to higher prices for land than assumptions made in 2015, before the $54 billion transit ballot measure was approved by voters.

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Projected costs for those two lines went from a total of $7.1 billion to between $12.1 and $12.6 billion, depending on where stations are located and how they are built.

As Sound Transit examined the construction market, staff members found that some contractors increased bids on other projects and lengthened projected project completion-time requests in order to attract enough workers.


The agency absorbed cost increases in bids for Lynnwood and Federal Way light-rail extensions now under construction, said agency spokesperson Geoff Patrick.

Costs also have been driven by project upgrades, such as replacing surface storm water management with underground facilities. Environmental conditions and additional requests from local jurisdictions and members of the public also add to the higher costs.

The bigger price tags come despite a move from the Sound Transit board to consider forgoing a $450 million tunnel to Ballard, a $200 million tunnel through a West Seattle neighborhood and elevated trackway in Sodo that would have blocked existing light-rail service during construction in favor of cheaper options. However, those options have not been eliminated. The Sound Transit board will make final decisions after reviewing a final environmental impact statement.

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Seattle Mayor and Sound Transit board member Jenny Durkan said she had concerns about the cost estimates and the timeline of when the board was informed.

“Some of this information obviously was available at a time when we should have had it while we were deciding and approving increased costs for projects over the last year,” she said.

Durkan, calling the rise a “significant jump,” also said board members should be more flexible in which sites are chosen for stations, especially if the cost of land continues to rise.

Voters in 2016 approved the $54 billion Sound Transit 3 tax measure to expand regional rail and bus service. The agency had promised West Seattle stations in 2030 and stations in Seattle Center and Ballard by 2035.

Board members will convene in a workshop Jan. 21 to start determining how project plans and schedules should be adjusted based on revenue drops from the COVID-19 pandemic. Part of the equation will depend on Sound Transit’s ability to secure additional money through state and federal sources, Patrick said.

Three West Seattle stations and a larger Sodo station are projected to serve 35,000 daily boardings, while five stations between Ballard and South Lake Union are expected to see daily ridership of 52,000.

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ST3 cost estimates were informed by the price of light-rail extensions to Lynnwood and Federal Way along with previously completed projects. The original estimates were “conceptual in nature” and “based on very limited design plans,” Kimberly Farley, the agency’s deputy CEO, said Thursday.

Patrick said actual projected costs will become more clear as projects advance to around 60% of the final design.

An independent assessment will review how Sound Transit develops cost estimates to understand where the approach worked, where it has not worked, and what accounts for the differences. A consultant, who will determine whether Sound Transit should use a different methodology going forward, will conduct an expedited review, slated for April.

Sound Transit is also considering three sites for its future maintenance base in South King County. The facility is scheduled to open in 2026 and service 140 light-rail cars. A larger site is now needed to accommodate a larger building and additional tracks.

A site that includes Dick’s Drive-In in Kent was previously a contender but later nixed due to public outcry and concern from Dave Upthegrove, a Sound Transit board member and Metropolitan King County Council member, that the land should be prioritized for transit-oriented development, such as housing, retail and offices, rather than a maintenance base.

The cost of the line between Tacoma and Federal Way has grown by more than a third, from its initial estimate of $2.4 billion to $3.3 billion, mostly due to new requirements for storm water collection and the elevation of 3 miles of trackway along Interstate 5 that was previously planned to be at-grade.

The new alignment will minimize impacts to the Hylebos Creek system and to important cultural and historical areas that staff identified as sensitive through investigations and tribal meetings.

Meanwhile, Sound Transit is building new bus-rapid transit projects along Interstate 405 and Highway 522 under budget, thanks to existing roadway owned by the Washington State Department of Transportation and changes in design that reduce the amount of land needed to be purchased.