Downtown Seattle viaduct is closing permanently in early 2019

Existing condition of the waterfront area in downtown Seattle. (City of Seattle)

The end is in sight for Washington State’s very own ‘big dig’ – the $3.3 billion USD Alaskan Way Viaduct replacement tunnel project.

Officials with the state government’s Department of Transportation announced this week that the existing viaduct – the elevated section of State Route 99 – running along downtown Seattle’s waterfront, will be permanently on January 11, 2019.

Existing condition of the waterfront area in downtown Seattle. (City of Seattle)

The stacked four-lane tunnel that will replace the Alaskan Way Viaduct. (Washington State Department of Transportation)

However, the new four-lane, 3.2-km-long replacement tunnel that parallels the old viaduct route will not immediately open to coincide with the closure.

Construction crews will need a three-week period after the closure to detach the old road connections and establish the new connections to the new road network. The disruptions to traffic could last for up to six weeks, as crews will also need to close the major southbound ramp to South Atlantic Street one earlier than the viaduct closure, and the northbound ramp to South Dearborn Street will open two weeks after the initial opening of the tunnel.

January 2019 construction work on Alaskan Way Viaduct connections. (Washington State Government)

During this final construction period, the 90,000 vehicles per day that normally use the viaduct will need to find another way to get to – or through – downtown Seattle. Traffic is expected to spillover into local streets in and around the city centre area.

The final lap of disruptions ahead of the new road system’s full opening has been billed by the state government as the longest major highway closure in Puget Sound history.

The tunnel was originally scheduled for an opening in late-2015. This was delayed however, due to a two-year delay on completing tunnel boring work, which was completed in April 2017.

Under the updated construction and implementation timeline, the viaduct was scheduled to be closed later this fall, but the state government said a decision was made to move it to January to avoid the peak holiday travel season, weather, and provide ample notice to the public.

Following the demolition of the viaducts, the City of Seattle is expected to commence major work on a $700 million USD renewal project of its downtown waterfront, which will include a new eight-lane surface roadway and extensive public spaces that connect the city centre with the water.

Current condition

Existing condition of the waterfront area in downtown Seattle. (City of Seattle)

Future condition

Artistic rendering of Waterfront Seattle. (City of Seattle)

See also