Aug. 17 project update: Reconnecting Bertha’s front end

Posted on Aug 17 2015 3:35 PM

Seattle Tunnel Partners has begun reconnecting the two largest pieces of the SR 99 tunneling machine’s front end. On Saturday, Aug. 15, crane crews from Mammoet lifted the machine’s bearing block into place atop the cutterhead and drive unit. The newly reconnected front end of the machine will remain at the surface while Hitachi Zosen installs its motors. When installation of the motors is complete, Mammoet will lower the 2,000-ton piece back into the pit. This narrated video (links to YouTube) explains the repair sequence in detail.

STP’s most recent schedule indicated the lowering of pieces would begin in early August, but some parts had to be remanufactured due to tight tolerances – measured in millimeters – that need to be met as the machine is reassembled. Those new parts have since arrived and been successfully installed. STP has a plan in place to resume tunneling in late November as scheduled. The state cannot verify the contractor’s schedule.

Once the machine is in the pit, crews will begin the lengthy task of reconnecting wires, hoses and other parts to the portion of the machine that remains in the ground. A series of tests will follow to ensure the machine is ready to resume mining.

We will continue to provide updates as STP’s repair effort continues. You can also track their progress by watching our construction cameras and following Bertha on Twitter @BerthaDigsSR99.

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