By Lindsay Peyton

Replacing the Alaskan Way Viaduct with a tunnel through the center of Seattle has been a monumental job.

Joe Hedges, Washington State Department of Transportation’s administrator of the project, compared the task with another giant step during his address to the West Seattle Chamber on Thursday, June 8.

“It was deemed to be, in the tunneling world, going to the moon,” he said.

Hedges added that the $1.4 billion tunnel, which is 60-ft. in diameter and 5 stories high, is “within the five top projects in the nation right now.”

The structure will house a two-story, two-lane road with 8-ft. shoulders. A ventilation system will extract 1.14 billion cubic feet of air per minute.

“A tunnel this diameter has never been bored in soft dirt before – the first of it’s kind,” Hedges said.

In fact, he believes that the Alaskan Way Viaduct Replacement has been inspiring to others in construction and engineering industries.

“Seattle’s set the new gold standard for tunnels,” Hedges said.” As a result, the interest in tunneling is piquing.”

There’s a light at the end of the project for Seattle, he added, as the entire $3.4 billion construction effort is 85 percent complete.

“All that two decades [of work] and thousands of people’s contribution of is going to transform Seattle for the next couple of centuries,” Hedges said.

The most recent portion was the Dearborn Street off-ramp bridge.

“That’s the next generation bridge,” Hedges said. “It’s a bridge not just designed to stay standing and safe during an earthquake but to survive an earthquake.”

He said new technology and the use of titanium rebar and flexible concrete made the bridge more durable. “This is a prototype that will survive and endure,” he said.

The next major step is tearing down the Viaduct, Hedges said.

He admitted that city residents are upset about losing the roadway – and their view of Seattle.

He believes that the tunnel will pay off, however, due to the addition of surface streets along the waterfront.

“It’s going to improve the mobility of Seattle,” Hedges said.

He explained that the northbound lane of the tunnel is two-thirds of the way completed.

“As we were boring, the construction was going on in back of us,” he said. “The road is being built. Right now, things are going very smoothly with the roadway. No issues there.”

The SR 99 tunneling machine, nicknamed Bertha, will now be demolished, and the heavy steel saved for salvage.

“Now her reward for a great job done is dissection,” Hedges said. “We’re taking her apart piece by piece.”

A part of Bertha could be saved and turned into a monument.

While the Viaduct is being demolished, there will be no ability to traverse roadways in that area.

“For three weeks or so – no tunnel, no Viaduct,” Hedges said.

The tunnel is slated to open in January 2019

Once complete, there will be a toll for those traveling on the underground roadway.

Hedges did not know the amount that will be charged.

“As soon as you toll the road, regardless of the toll, significant diversion happens,” Hedges said.

He still believes that the tunnel will be widely used to avoid traffic congestion downtown.

Pete Spalding, a member of the chamber’s board of directors, also served on an advisory committee concerning the Viaduct.

“I’ve been attending meetings on the Viaduct for 10 years,” he said. “The first year, we met 21 times. Our choice was to move forward with the tunnel. Now all the construction is going to come to an end. Bertha is finished digging.”

Spalding believes West Seattle residents will benefit from the tunnel, especially if they want to quickly move to the north side of town.

“It’s going to be a big advantage,” he said.

When the existing streets connect across where the Viaduct once stood, Spalding said traffic will move faster.

“They’re going to be able to reconnect portions of the street grid that have been disconnected since they opened the Viaduct,” he said. “What was once blocked by 99 won’t be anymore.”

For more information about the Alaskan Way Viaduct Replacement Program, visit www.wsdot.wa.gov/Projects/Viaduct/.

For more information about West Seattle Chamber events, visit www.wschamber.com.