Seattle Tunnel Partners has successfully lowered three large pieces of Bertha, the 17.52m diameter Hitachi Zosen EPBM SR 99 tunnelling machine’s front shield into the access pit for reassembly meaning that all major components of the TBM are now in the pit.
On Saturday, Aug. 29 and Monday, Aug. 31, respectively, crane crews from Mammoet lowered two 98-ton side body pieces.
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On Friday, Sept. 4, the 278-ton middle shield was lowered.
With all major components of the machine now in the pit, crews are focusing on reassembling the machine and preparing for the testing phase of the repair effort. Crews will spend the coming weeks welding pieces back together, in addition to the lengthy task of reconnecting the hundreds of wires and hoses that are integral to the tunneling operation. STP and Hitachi Zosen will conduct a series of tests following reassembly to ensure the machine is ready to resume mining.