Feb. 18 project update: Bertha on the move
Posted on Feb 18 2015 9:00 AM
Last night, Seattle Tunnel Partners began mining through the southern wall of the SR 99 tunnel access pit. As of 7 a.m. on Feb. 18, Bertha, the SR 99 tunneling machine, had moved more than three feet.
The machine must mine through 20 feet of unreinforced concrete to reach the pit. The duration of this effort will depend on the machine’s ability to mine through the concrete while operating with a damaged seal system. STP anticipates the machine may overheat, as it has during their most recent attempts at mining. If the machine becomes too hot, they will take a break for it to cool down before resuming.
Work to chip away a Bertha-sized circle on the face of the pit’s southern wall wrapped up yesterday. This allows for a cleaner breakthrough when the machine moves into the pit. Watch a video (links to YouTube) of the work.
Moving Bertha into the pit is just the beginning of the repair process, which this narrated video (links to YouTube) explains in detail. The machine must be partially disassembled before it can be lifted to the surface, a process that STP has said will likely take significant time and effort.
We recognize that the public has great interest in the outcome of STP’s repair effort, and we are committed to providing regular updates on Twitter and our website as their work moves forward.