After eight weeks of heavy lifting and assembly, crews lowered Bertha’s 838-ton cutterhead into the SR 99 tunnel launch pit last Friday. Bertha is the world’s largest tunneling machine.
Crews are now working on welding the pieces together, connecting wires and hoses and testing the machine, which will take about two months. Bertha is expected to start digging this summer.
Don’t forget to visit Milepost 31 the project’s information center in Pioneer Square, where you can see the 10-foot-long interactive model of Bertha. You can also join WSDOT for a conversation about operating the SR 99 tunneling machine this week:
Thursday, June 6
6 to 7 p.m.
211 First Ave. S., Seattle
Admission is free.