A long road ahead for Bertha as it finishes digging under viaduct

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SEATTLE -- The state reopened the Alaskan Way Viaduct early, in time for Monday morning’s commute, with Bertha still digging near the structure.

The Washington State Department of Transportation said officials decided to reopen the viaduct five days early because the dig showed no negative impacts to the structure. The department credited its contractor, Seattle Tunnel Partners, for a job well done during Monday’s press conference.

But the tunnel project is far from over.

Once Bertha clears the entire 385-foot dig from one side of the viaduct to the other, it will continue its journey underground between Western and 1st Avenue. Then Bertha travels directly beneath 1st Avenue for a long time.


Sitting at 1st and Pike, Metsker Maps is keeping a close eye on Bertha's progress since the tunnel-boring machine will eventually dig underneath their business.

“The building has been earthquake retrofitted in the last few years,” Metsker Maps co-owner Skip Ross said.

Ross said he's also relieved WSDOT installed sensors underground to monitor for any movement.

“I would hope that the ground is structurally sound,” Ross said.

He's worried about vibrations setting off the sprinkler system and ruining his precious maps.

“We are going to be entering a zone now that's largely clay, which is particularly good,” Chris Dixon of STP said.

Dixon said businesses most likely will not feel a thing as Bertha snakes underground through downtown Seattle.

If Bertha hits a boulder, for example, STP says there is a slight chance for vibrations but they have plans to mitigate those issues.

“So there may be some vibrations if we encounter boulders,” Dixon said.

Additional challenges include more pressure as Bertha digs deeper and the soil changes from clay to gravel and sand later on in the project.

“Dealing with ground conditions as we encounter them,” Dixon said.

People like Ross are hoping for the best. He said that WSDOT’s success of digging safely under the viaduct is giving him hope the rest of the project will go smoothly.

“I can see why they are patting themselves on the back, they haven’t had a lot of good news to report,” Ross said.

The tunnel project is divided up into 10 zones; currently it is in zone 2. The tunnel is expected to open in summer 2018.