Why Bertha hasn’t moved since the holidays
Jan 13, 2017, 12:55 PM
Bertha’s crew returned from holiday break on Jan. 5, but work only just resumed.
For the past two weeks, Bertha’s cutterhead has been in聽maintenance. The tools at the front of the boring machine are individually tightened onto the cutterhead. When they wear down, they have to be replaced, and that involves a lengthy process. Bertha has stopped frequently for such maintenance during its journey.
Related: Bertha crews install 1,000th tunnel ring
This means crews are, once again, going into hyperbaric conditions. The boring machine is essentially like a submarine under Seattle. Compressed air has to be pumped into the front of the machine to keep soil and water back. Workers then have to go into pressure chambers to adjust to the change at the front of the machine. Crews can only work up to 45 minutes at a time under such conditions.
The Washington State Department of Transportation reports that the machine will begin moving once the maintenance is complete, but it has not said exactly when that will be.
Where is Bertha?
Bertha is — out of 10 zones — placing it roughly 160 feet underneath Third Avenue, between Blanchard and Bell streets. There is about 2,500 more feet to go before the end of its journey. That means 2/3 of its journey is complete.
Above Bertha is mostly apartment buildings. There’s one masonry building built in 1929, and a parking structure built in 1979. There’s also an apartment building built in 1925 on that stretch. Also, a newer mixed-use apartment building that went up in 2014. Finally, Bertha will pass under a building built in 1925 — currently there’s a restaurant at that location.
