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October 2011 Alaskan Way Viaduct closure

Why did WSDOT close the viaduct in October 2011?

We finished building the first of two side-by-side bridges that will replace the viaduct’s southern mile. On Oct. 21, 2011, we closed SR 99 and began demolishing part of the viaduct. When SR 99 reopened to traffic on Oct. 29, both directions through SODO traveled on the new bridge. We then finished demolishing the viaduct’s southern mile without disrupting traffic on SR 99, and began building the second new bridge. 

How to access the viaduct after the closure

Drivers can access the viaduct as they did before the closure. Northbound drivers enter SR 99 from South Royal Brougham Way. Southbound SR 99 drivers access SODO by exiting SR 99 at South Atlantic Street.

Learn (pdf 512 kb) more about how traffic changed during the course of

Changes to SR 99 after the October 2011 closure

Traveling on a new bridge

Both north and southbound traffic travel on the first of two new bridges. The second new bridge is scheduled to open to traffic in 2013. When the new roadway is complete, the west bridge will be used for southbound traffic, and the east bridge for northbound traffic.
Using a construction bypass

Drivers pass through a construction bypass between South King Street and South Royal Brougham Way. The bypass connects the new SR 99 bridge to the viaduct at South King Street. It keeps traffic on SR 99 moving while work continues on the viaduct replacement.

South of South King Street, SR 99 has two lanes in each direction. North of South King Street the viaduct remains in its current configuration with three lanes in each direction.

Reducing the speed limit 

The speed limit on the majority of the viaduct is reduced to 40 mph. The construction bypass carries an advisory speed limit (pdf 751 KB).

The map below shows the construction bypass and reduced speed limit on SR 99.