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Workers emerge from behind the tunnel machine’s cutterhead after Bertha punched through the wall at the disassembly pit in Seattle on Tuesday. (GeekWire Photo / Kevin Lisota)

From the dark depths beneath Seattle, Bertha the SR 99 tunnel machine headed out of the muck and into daylight on Tuesday, completing a final push in a years-long effort to create space for a new highway beneath the city.

GeekWire was on site, waiting (watch the Facebook Live video above) in the noise and dust of the receiving pit near Sixth Avenue North and Thomas Street as the machine’s 5-story-tall cutterhead ground its way through a 5-foot-thick concrete wall.

As the morning wore on Tuesday, giant chunks of concrete laced with rebar began to fall to the floor of the receiving pit, which was flooded with a mixture of muddy water and the solution used to lubricate the giant cutterhead.

Loud cracks and grinding noises pierced the air just blocks from the Space Needle as Bertha slowly inched forward and the cutterhead became visible.

From about 9:30 a.m. to 11:30 a.m., the view of the receiving pit was mostly clouded by concrete dust. (GeekWire Photo / Kevin Lisota)
Bertha’s cutterhead is visible after busting through on Tuesday. (GeekWire Photo / Kevin Lisota)
A WSDOT drone, center, was flying into the pit to get a great perspective on Bertha’s arrival. (GeekWire Photo / Kevin Lisota)

“It’s a great day, isn’t it?” said Joe Hedges, project administrator with the Alaskan Way Viaduct Replacement Program. “Standing in the dust cloud of success!”

Around noon, the machine ground to a halt.

Back up at street level, officials were waiting to hail Bertha’s arrival as a great day for the state of Washington, the city of Seattle, King County and the Port of Seattle.

“This is a big milestone on a bold project,” Washington Gov. Jay Inslee said from the site. “And we are a big and bold state. We can all be glad that our state has been persistent in fulfilling this job, insistent on calling everyone to get this job done and now committed to safely fulfilling this job. We are in a race to provide for the safety of Washingtonians … and today we’ve got ourselves a tunnel!”

Washington Gov. Jay Inslee comments on the arrival of Bertha on Tuesday in Seattle. (GeekWire Photo / Kevin Lisota)
Workers pose with Bertha as a backdrop. (GeekWire Photo / Kurt Schlosser)
It will take months to get Bertha into the disassembly pit, cut up, lifted out and hauled away. (GeekWire Photo / Kurt Schlosser)

Seattle Mayor Ed Murray called the completion of the tunneling operation a “transformative moment” for the city and referenced the eventual evolution of the waterfront and the construction of a “world-class park” to connect the city back to the water.

Bertha traveled more 9,270 feet from the southern end of downtown and placed more than 1,400 concrete rings along the way to form the outer wall of one of the world’s biggest and most complex tunnel mining operations. The project’s ultimate aim is to replace the earthquake-vulnerable Alaskan Way Viaduct, the elevated waterfront highway which opened in the 1950s.

The tunneling phase of the project began in July 2013 but was soon plagued by a two-year delay caused by damage to the machine and repairs that followed. Construction of the double-decker highway inside the tunnel is ongoing and traffic isn’t expected to hit the roadway until January of 2019.

Look back on more of GeekWire’s extensive coverage of Bertha and the project to replace the Alaskan Way Viaduct in Seattle.

Tunnel map
(WSDOT Graphic)
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