UPDATE: Seattle Tunnel Partners has informed the Washington State Department of Transportation that crews will not lift the first piece of the front shield on Bertha today. A WSDOT spokesperson says not to “read anything more into this other than STP is being careful and will perform the lift when they are ready.”
While crews begin repairing the world’s largest tunneling machine Wednesday, two other boring machines continue chugging along under Seattle’s streets.
You may not realize it because big Bertha has stolen the spotlight, for better or worse, but she has two little little sisters, Brenda and Pamela. The pair is working on Sound Transit’s light rail project between the U-District and Northgate.
Brenda and Pamela are much smaller, about 22 feet in diameter, as compared to Bertha’s 57 feet. They are working on a 1.5 mile stretch between the future Maple Leaf light rail station, located just south of Northgate, and the new Roosevelt station.
The tunnels and stations are part of the Northgate Link Extension that will connect to the U-District station. Service is expected to begin in 2021.
Brenda has been churning at about 100 feet a day since July 2014. The machine broke through the wall into the Roosevelt station on Tuesday. She will now take a much-needed break for maintenance before moving to the south end of the Roosevelt station to begin tunneling toward the U-District.
Pamela is digging a parallel tunnel from Maple Leaf to Roosevelt, which she is expected to reach this summer. She has been drilling since November.
As for Bertha, a giant crane assembled above a repair pit on the Seattle waterfront is expected to remove a part of the machine’s outer casing Wednesday. Two more pieces will need to be removed before crews can get to the cutter head to make repairs.
Drivers on nearby Highway 99 may notice a large frame, which is part of a canopy being set up to protect workers and machine parts from the elements during repairs.
Bertha is expected to resume tunneling in August. While boring for the Seattle waterfront tunnel is on hold, the Washington State Department of Transportation said the work was about 70 percent complete as of December 2014.