Scrambling to Replace the Heavily Used West Seattle Bridge

Seattle Mayor Jenny Durkan has announced a position on one of the big questions hanging over Seattle: What to do about the West Seattle Bridge more than six months after being closed when quickly growing cracks were discovered in the bridge in March 2020. The Seattle Department of Transportation (SDOT) spent most of the year trying figure out how to prolong the life of the West Seattle High Bridge—or give up and replace the bridge entirely. 

Mayor Durkan today announced a preference for the replace option, according to an article by Mike Lindblom. Now, the "Seattle Department of Transportation (SDOT) will go ahead with a 'type, size and location' study for a replacement structure," reports Lindblom. "That study will likely include not only bridge concepts but a shallow immersed-tube tunnel..." The tunnel concept was initially part of the discussion as a replacement for the bridge's 125,000 daily trips.

Shaun Kuo has been following the progress of SDOT over the past few months, as it laid out six options to "shore, repair, or replace" the bridge, as well as a Cost-Benefit Analysis (CBA) performed by WSP. The CBA reduced the number of viable options by one, but doesn't provide a recommendation for how the SDOT should proceed.

Kuo offers detailed insight in the Cost-Benefit Analysis, and concludes by offering an indication of which direction SDOT might be headed for the future of the bridge:

While further study is desired and some West Seattleites demand the option with the quickest reopening of the West Seattle Bridge, city staff are reportedly leaning toward replace with the entertainment of rapid replace. With future compatibility with light rail in mind, The Urbanist has come out in favor of replacement. 

Obviously, Kuo's insight is proven prescient by Mayor Durkan's announcement today.