Widespread traffic gridlock expected as Alaskan Way Viaduct closes next Friday for Bertha dig

SEATTLE -- Next Friday, the Alaskan Way Viaduct will close for two weeks so Bertha can dig a tunnel only 15 feet below the foundation -- the closest the machine will come to any structure.

When the huge machine crosses under Alaskan Way and Yesler Way, people may not feel the vibrations from the dig but many are likely to feel the pain of the resulting traffic gridlock.

“It`s not going to be pretty,” commuter Tammie Burks said.

Commute Seattle, along with the Washington State Department of Transportation, handed out brochures Friday encouraging companies and employees to change work hours.

“If you don't have the ability to flex your hours, one great option, at least in the evening, is to stay downtown go to happy hour,” said Jessica Szelag, executive director of Commute Seattle, an organization supported by the Downtown Transportation Alliance.

During a 2011 viaduct closure, the morning commute started two hours early, at 4 a.m., and lasted until 10 a.m. Going home, traffic built up as early as 2 p.m. and stayed congested until 8 p.m.

And don`t think you`ll only feel it in Seattle. The gridlock will likely stretch up and down Interstate 5, I-405 and the bridges between Seattle and the Eastside.

“It`s the one safe route, to take the train,” Burks said.

About 90,000 cars use the viaduct each day. As tough as it will be on traffic, WSDOT said, they need to shut it down so they can monitor the structure as Bertha passes underneath.

“It’s the most analyzed, most inspected structure in all of Washington state. We have a very good handle on it, we can monitor it to a millimeter worth of movement,” David Sowers of WSDOT said.

And the engineers have shored up the viaduct with underground pilings, vertical steel beams and carbon fiber to make sure nothing will go wrong.

WSDOT said they don`t see the need to bar ground traffic from the area underneath the viaduct during Bertha's dig. They believe it`s safe and will only create more chaos by restricting traffic.

Engineers say they are confident Bertha will not get stuck under the viaduct. If something does go wrong WSDOT says, they plan to keep the viaduct closed to traffic until Bertha can dig 350 feet to the other side.