Sound Transit releases new cost estimates for tunnel options to West Seattle and Ballard

Sound Transit on Thursday released a new analysis showing light rail tunnels requested by community and political leaders would each add hundreds of millions of dollars to the cost of bringing train service to West Seattle and Ballard.

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The agency said tunneling beneath Pigeon Point in West Seattle would increase the cost by around $200 million. That’s on top of the $700 million more it would cost to also tunnel to the West Seattle Junction.

Tunneling to the Junction would also push the opening date for light rail beyond 2030, Sound Transit officials said.

The costs in the analysis compare to the representative alignment in the $54 billion Sound Transit 3 ballot measure that regional voters approved in 2016, which called for mostly elevated tracks to Ballard and West Seattle.

Concerned about the impact on neighborhoods of elevated tracks and trains delayed by a drawbridge over the Lake Washington Ship Canal, people in both Ballard and West Seattle have called for tunnels, although it’s not known where the extra money would come from.

In May, elected officials on the Sound Transit board advanced several alternatives for environmental review, including more expensive options that would require still-unidentified “third party funding.”

Agency officials say they would need a commitment for extra money by mid-2022 if Sound Transit is to stay on track opening light rail to West Seattle in 2030 and Ballard in 2035.

Sound Transit officials also did an initial assessment of an idea brought up during public comment for a station in the heart of Ballard, near 20th Avenue Northwest and Northwest Market Street, instead of on 14th Avenue or 15th Avenue Northwest and Market.

Agency staff members found that running a line over Burlington Northern Santa Fe tracks in Interbay and tunneling beneath Salmon Bay to 20th would cost an additional $750 million.

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They also looked at tunneling beneath Fishermen’s Terminal just north of the Ballard Bridge, which would require $450 million in extra money.

A tunnel to 14th Avenue or 15th Avenue would cost $350 million more than the ST3 representative alignment.

Agency officials say their analysis does not show more people would use a 20th Avenue station in the heart of the neighborhood because most riders would be transferring to buses anyway.

The agency also found that building double-elevated tracks in SoDo to reduce impacts on nearby businesses would add $300 million to the cost of the project and would require two major shutdowns of Central Link service during construction.

Sound Transit’s board of directors will decide in October whether to advance any of these ideas for environmental review, along with the concepts they agreed to study in May.

The analysis is expected to take through the end of 2020, with the board choosing a preferred alternative in 2021.

By Graham Johnson, KIRO 7