Bertha makes it through concrete wall into access pit

After sitting idle for more than a year, Bertha the drill broke through a 20-foot wall of concrete on the Seattle waterfront Thursday afternoon.

The world’s largest tunneling machine will go two more feet before stopping to build another concrete tunnel ring.

The Washington State Department of Transportation said Bertha will continue to move forward in 6 and a half foot increments, stopping to build concrete rings on its way into the pit.

Once Bertha’s front end is entirely exposed in the pit, crews will begin the dismantling process.

“STP has told us that taking the machine apart and lifting it to the surface will take significant time and effort,” said WSDOT.

Once the disassembling process is complete, a massive crane will lift the front of the machine to the surface for repairs and improvements.

“We’ve got seals, that are rubber seals that prevent metal to metal contact between the rotating piece and the fixed piece,” explained Chris Dixon, project manager with Seattle Tunnel Partners. “We filled that with grease. Those seals became damaged and that’s what we’re replacing.”

WSDOT said workers and manufacturer Hitachi Zosen will continue to monitor Bertha to make sure it doesn’t overheat.

The tunnel, which will run about 2 miles under the city, is designed to replace the Alaskan Way viaduct, damaged in a 2001 earthquake. The project is two years behind schedule.

If all goes as planned, the tunnel is expected to open to traffic at the end of 2017.

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So what’s next? Seattle Tunnel Partners released a repair plan via video in June: