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Bertha completes Seattle tunnel dig, next phase of construction begins

SEATTLE — Bertha is done digging.

After four years of moving — and sitting broken for a while — underneath downtown Seattle, the world’s largest tunnel-boring machine on Tuesday reached the end with much fanfare.

Q13 News streamed it live online and on Facebook and 2 million people watched the cutterhead break the final wall into the disassembly pit near Seattle Center.

It’s all for a double-decker highway that will go in the tunnel. Southbound lanes will be on top and northbound lanes on the bottom. Both will carry hundreds of thousands of drivers every day when the tunnel opens in early 2019.

Crews will have a lot of plumbing, electrical and mechanical features to work out, not to mention more than 8,000 tests to make sure the tunnel is safe for drivers. As crews get ready for that endeavor, hundreds on Tuesday paused for the historic moment and watched Bertha break through to its final destination.

During the process Bertha sounded like a whale at times, then a raging river.

The gushing water was the first sign of Bertha’s birth into daylight. Chunks of concrete started to rain down, and the people who worked for years for the monumental moment tried not to blink.

“It’s a unique experience,” the Washington State Department of Transportation's Roger Millar said.

The haze of concrete dust made it hard to see. The anticipation, nevertheless, built up, then finally a tunnel the size of 6 stories opened up.

“Machine was right on alignment, broke through at the exact spot it was supposed to,” said Chris Dixon, with the contractor Seattle Tunnel Partners.

The delayed journey and cost overruns took a backseat during the celebration.

“The only stronger is King Kong; now we got ourselves a tunnel,” Gov. Jay Inslee said.

“Thank you Bertha, it’s time for the next stage,” Seattle Mayor Ed Murray said.

The next phase entails months of taking apart the largest tunnel-boring machine in the world. Some parts will be recycled and others shipped back to the machine’s creator in Japan.

“We have to clean all the debris that you see,” Dixon said.

Then the work begins on finalizing the tunnel that will replace the elevated Alaskan Way Viaduct for good.