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Update: Viaduct to close for 9 days to put up detour connections

Construction of the new southbound SR 99 roadway underway just west of the Alaskan Way Viaduct in Seattle.
Construction of the new southbound SR 99 roadway underway just west of the Alaskan Way Viaduct in Seattle.

It’s the beginning of the end for the Alaskan Way Viaduct.

Demolition work will shut down the double-decker highway for 9 days about two months from now, from October 21 – 31. According the state Department of Transportation, it’s the longest full closure of a Seattle area highway the city’s ever dealt with.

During the closure, crews will start demolishing a section of the viaduct near Safeco Field. The biggest portion of the double-decker highway will remain up until a tunnel is complete. But on the southern end, big portions will come down and they’ll put in temporary connections to an s-shaped detour that drivers will use over the next four years.

Make plans for it

Right now, 110-thousand drivers still use the viaduct every weekday. 

“So, it’s gonna be hard,” says Matt Preedy, who directs the construction projects on the south end of SR-99 for the state Department of Transportation.

“You know, you don’t just move 110,000 cars onto the surface streets or onto I-5. A lot of those facilities are already at full capacity. History has shown that when we get out in advance of a major closure like this in the Seattle area, and let people know, they can make plans, ” Preedy says.

Metro is adding bus service to entice new transit riders on routes between downtown, West Seattle, White Center and Burien. Other alternatives officials are encouraging include van pools, water taxis and light rail – or telecommuting and taking vacation during that last week of October. 

How well all of this works will be instructive. WSDOT says there will be another major closure of highway 99 along the waterfront: Four years from now, when the tunnel is complete, it will take two weeks to connect it.

Bellamy Pailthorp covers the environment for KNKX with an emphasis on climate justice, human health and food sovereignty. She enjoys reporting about how we will power our future while maintaining healthy cultures and livable cities. Story tips can be sent to