SR 99 tunneling machine problem nearly fixed

Last month we reported that Bertha, the machine that will dig the SR 99 tunnel, was in the midst of an extensive testing program at the manufacturing plant in Japan. During testing crews discovered a problem with Bertha’s main-drive unit, which rotates the cutterhead at the front of the machine. She has since been partially disassembled so engineers could take a closer look at the issue.

The diagnosis? Bertha’s going to be just fine.

In fact, further examination of her main-drive unit confirmed what Hitachi Zosen, the tunnel boring machine supplier, suspected when they first discovered the problem: a tolerance issue in the main-drive unit that occurred during assembly. Their quick diagnosis is helping to expedite the fix because they were able to order the parts they needed while the machine was being taken apart. Crews are now repairing the damage so Bertha can be reassembled, retested and shipped to Seattle this spring.

Seattle Tunnel Partners (STP), our tunnel contractor, expects Bertha to arrive in Seattle in late-March, a few weeks later than originally planned. This type of minor schedule adjustment is an expected part of a project this large, and will not impact STP’s overall project completion schedule. We still expect tunneling to begin this summer, and the tunnel to open in late 2015.

See you soon, Bertha.