Jan. 5 project update: Bertha reaches next planned maintenance stop

Posted on Jan 5 2017 2:31 PM
During the holiday break, Seattle Tunnel Partners performed routine maintenance and inspections on Bertha, the SR 99 tunneling machine. This included inspection of some of the machine’s cutterhead tools under normal atmospheric pressure. STP decided to begin a hyperbaric maintenance stop this week to inspect the other cutterhead tools on the machine under hyperbaric conditions (this post explains the different types of tools in more detail).  
Crews plan to spend between one and two weeks inspecting the tools, and replacing them as necessary. However, the duration of the stop could be longer or shorter depending on the number of tools that need to be replaced. STP’s most recent hyperbaric maintenance stop in late October lasted one week. 
The top of the cutterhead is located approximately 160 feet below Third Avenue, about halfway between Blanchard and Bell streets. Crews are less than 2,500 feet from the receiving pit near Seattle Center where Bertha will emerge at the end of her 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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