In the home stretch: Bertha being prepped to dig final 1,000 feet of Seattle tunnel

SEATTLE -- The dig on the Seattle tunnel has been stopped to prepare the huge boring machine Bertha to cut through the final 1,000 feet of the 9,270-foot drive, the Washington State Department of Transportation said Tuesday.

"Crews stopped mining yesterday to verify Bertha’s position along the tunnel route before making their final push to the disassembly pit," the end of the line for Bertha, WSDOT said.

The department said recent surveys show that Bertha may be several inches off of the tunnel alignment, but added that "adjustments are common during tunneling, including on this project."

WSDOT said crews will continue to perform routine maintenance on the machine for the next several days. They plan to resume mining next week.

According to the contractor's most recent schedule, Bertha will arrive at the disassembly pit in May, WSDOT said.

The pit is about 960 feet north of the cutterhead’s current location beneath Denny Way and 6th Avenue North.

"Crews successfully mined under the final building of the tunnel drive earlier this week. Bertha has traveled a total of 8,310 feet and built 1,270 of 1,426 concrete tunnel rings," WSDOT said in a news release.