Oct. 12 project update: After a brief checkup, Bertha is back on the move

Posted on Oct 12 2016 10:59 AM
Seattle Tunnel Partners resumed mining on Tuesday following a week of planned maintenance on Bertha, the SR 99 tunneling machine. During the stop, crews performed routine maintenance, including the inspection of cutterhead tools.
Crews initially expected to spend several weeks changing tools in hyperbaric conditions. However, after a full day of hyperbaric work and tool inspection on Monday, STP determined the cutterhead tools were in satisfactory condition and decided to continue mining.  
With the machine functioning well and the cutterhead tools in good condition, STP will continue mining north beneath First Avenue. They plan to make at least one more stop to perform hyperbaric work, but the timing and location of future stops will be determined by STP based on soil conditions and maintenance needs. 
The top of the tunneling machine is located nearly 200 feet below First Avenue, approaching Pine Street. As of this morning, crews had tunneled 4,750 feet of the 9,270-foot-long tunnel drive. Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.
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