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Bertha is a tunnel boring machine built specifically for the Washington State Department of Transportation's (WSDOT) Alaskan Way Viaduct replacement tunnel project in Seattle. It was made by Hitachi Zosen Sakai Works in Osaka, Japan, and the machine's assembly was completed in Seattle in June 2013. The name Bertha, after Seattle's only female mayor, Bertha Knight Landes, was chosen by a panel (that included the Governor and Transportation Secretary) from submissions from kindergarten through 12th graders, who were asked to submit female names with Washington state heritage. By December 6, 2013, Bertha had tunneled , or 11%, of the total length of the tunnel, stopping about below ground between South Jackson Street and South Main Street. The machine's progress was halted on that day by an unexpected impediment. After a month's investigation, WSDOT announced that the machine's cutting blades had encountered an , steel pipe, one of several well casings left over from a previous 2002 drilling project that had assessed groundwater conditions and soil stability in the area in case of another earthquake, such as the 2001 Nisqually earthquake, which led to a need for the replacing of the Alaskan Way Viaduct in the first place. Because the machine cannot cut through metal, the pipe damaged several of Bertha's cutting blades, necessitating blade replacement before the machine could proceed. The pipes' locations were known to WSDOT and the agency thought they had been removed. It is unclear whether the state agency or one of its contractors is responsible for the left-behind pipes, as well as who is responsible for allowing the tunneling to proceed without their removal. In early February 2014, as Bertha was being prepared to resume operation, workers discovered it was overheating and that a damaged main bearing seal needed to be replaced. Multiple options were discussed to fix the problem, but Bertha was expected to be out of commission until March 2015. In December 2014, workers began digging a pit in order to lift Bertha's front end up to street level for repairs, but were delayed when groundwater pumping caused visible damage to nearby South King Street and some of its neighboring buildings. The front end of the machine, including the damaged cutter head, was successfully lifted onto the surface on the morning of March 31, 2015. Seattle Tunnel Partners, the contractors overseeing the project, estimated that fixing Bertha would delay the opening of the new tunnel by an additional nine months to August 2017, which was later extended to March 2018 after additional damage was discovered in June 2015. On May 18, 2015, WSDOT reported to the Seattle City Council that the damage to the bearing sand seals was worse than had been previously reported. Further inspection after the cutting head was removed and disassembled showed damage to the cutter head drive gears, so a new estimate of the repair time and cost was being prepared. The front end of the machine was lowered back into the access pit for reassembly in a four-lift process beginning with the repaired cutter drive on August 24, 2015. In June 2015, Seattle Tunnel Partners sued to force insurers to payout on the $85 million insurance policy to cover repairs needed after Bertha's cutting teeth were damaged in a collision with a steel pipe in December 2013. In August 2015, a consortium of eight insurers filed a lawsuit against STP in order to avoid a $143 million payout to cover the cost of repairs to the boring machine. The insurers claimed that the tunnel-boring machine's capabilities were inadequate for the project and should be excluded. As of September 2015, Bertha had traveled of its planned route from SoDo to South Lake Union. ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bertha (tunnel boring machine)」の詳細全文を読む スポンサード リンク
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