The District of Columbia Water and Sewer Authority (DC Water) recently christened a new Tunnel Boring Machine ‘Lady Bird’ in honor of former first lady Claudia Alta ‘Lady Bird’ Taylor Johnson. The roughly 23-ft diameter TBM will tunnel a total of over 24,000 feet at a depth of 100 feet below the Potomac and Anacostia Rivers as part of a DC Water project aimed at reducing combined sewer outfalls. I first posted about this project, including a Google Map of the route a few years back. [Source: More at Tunnel Business Magazine. Image: Tunnel Business Magazine]
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Feb. 7 Bertha update: Two factors contributed to tunnel stoppage
WSDOT released an update on February 7 with some conclusions regarding the blockage that has stopped the Alaska Way Viaduct Tunnel Boring Machine, Bertha’s progress since December 6. Now they don’t think it was necessarily the well casing after all.
They cite two factors that contributed to the blockage. First, the cutterhead was clogged with material. You can see an cool short video of a worker unclogging the cutterhead. Not terribly dramatic, but still cool. The second factor was increased temperatures inside the equipment. STP discovered damage to a seal that protects the machine’s main bearing. They are still determining how the repairs will be done.
If you want to follow the chronology of this issue, read below for summaries and links to previous updates from WSDOT. And Check out the videos too! [Source: WSDOT]