For the first time in more than a year, Big Bertha actually bored.
According to a report from the Seattle Times, the world’s largest tunnel boring machine, dormant deep below Seattle since late January 2014, has drilled forward a total of 6 feet between late Tuesday night and Wednesday afternoon as crews begin the process of moving Bertha into a 12-story repair pit for repairs.
Before she is ready for repairs, Bertha will have to chew through another 14 feet of concrete to enter the pit. Washington State Department of Transportation officials would not say how long it will take Bertha to enter the pit as they are taking the task very slowly to ensure that the machine does not overheat.
The machine is nearly two years behind schedule in digging Seattle’s new State Route 99 tunnel due to a long list of setbacks.
The massive machine went down only one-tenth of the way through digging the 1.7-mile tunnel which will carry a double-deck highway and replace the State Route 99 Alaskan Way Viaduct.
Water and sand clogging her cutterhead openings brought the machine to a halt, penetrating seven rubber seals meant to protect the main bearing. In repairing the machine, crews will lift the 630-ton cutterhead, drive axle and bearing to the surface and install 216 steel ribs and plates that will add 86 tons of reinforcement to the 7,000-ton machine’s drive block and cutter drive.
The repairs are expected to be completed by April.