The Alaskan Way Viaduct officially starts to come down

Following the opening of the new SR 99 tunnel through downtown Seattle, the Alaskan Way Viaduct was immediately scheduled for demolition. Snowstorms put a temporary halt to those plans, moving the start of the demolition to Friday.

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In total, 1.4 miles of roadway will be removed, comprised of 400 columns, and 61,000 cubic yards of concrete, weighing 122,000 tons. The viaduct will be treated as a series of bridges, with each section removed individually while adjacent sections stand.

It’s estimated that it will take six months to complete the removal, from South Dearborn Street to the south end of the Battery Street Tunnel. Work along the central waterfront area of the viaduct should be finished by June.

Kiewet Infrastructure West will be overseeing the demolition, cordoning off two to three blocks at a time, and spending roughly 30 days on each section. The viaduct will be dismantled level-by-level from top to bottom.

The difficulty of the project comes with how close the viaduct is from buildings and other elements of the city.

“What makes this unique is the close proximity of the buildings, [and] the massive grid of utilities that we’re going to be protecting,” said Dan Hemenway, Kiewet’s project manager overseeing demolition.

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Girders close to those buildings will be removed via crane, and in some cases, barriers will be added to protect them from rock, debris, and dust. Additionally, sensors will be implemented to ensure that noise and vibration are “kept within limit.”

The demolition process starts at the northernmost end of the viaduct near Bell Street, as well as by Pike Place Market, and the Columbia Street Ramp.

You can follow the whole process in real time on WSDOT’s demolition tracker here.

WSDOT expects the the waterfront, Alaskan Way, Pike Place Market, Pioneer Square, and access to the ferry terminal to all be open and available during the demolition.

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