Bertha’s back on the job after her holiday vacation. The people taking care of her, though, had to work under some odd conditions to make sure she can finish the tunnel. Decompressing from work takes on a different meaning.
The SR 99 Tunneling Machine, her more official name, is deep enough under Seattle that the head of the machine is effectively one hundred feet underwater. To check out the tools and the equipment that’s doing the tunneling, crews had to force compressed air into the space to drive out the water. That means the crews don’t have to wear underwater equipment, but it does mean they work in a literally high pressure environment, just like divers but without the water.
It sounds simple until you see the hyperbaric chambers, and the daily physicals everyone has to go through. WS DOT produced a video for the curious.
During weeks of work, they replaced 300 cutting tools that had worn down digging through the earth. Now, Bertha’s back at work and has made about another 35 feet of progress. Getting closer all the time.
STP is mining again after completing hyperbaric maintenance. ICYMI, here’s how crews perform this specialized work: https://t.co/opX3mOmC3O
— Bertha (@BerthaDigsSR99) January 17, 2017