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.
Bertha finally gets a face-lift! The cutterhead has dozens of ‘teeth’ that will chip away the ground as it rotates.
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.
Milepost 31
211 First Ave. S., Seattle
Admission is free.
Here you can see a portion of the covered conveyer belt system which will carry the excavated soil out of the tunnel to barges at Terminal 46. Also pictured are “Self-Propelled Modular Transporters”, specialized vehicles (sporting 96 axles and nearly 800 tires) that were used to carry the massive pieces of Bertha from the ship to the launch pit.
Cutterhead lowering – Up-close and personal