Seattle tunnel dig update: TBM "Bertha" off to a good, slow start

08/19/2013 | KING-TV (Seattle)

Bertha, the massive tunnel-boring machine that is digging a tunnel to replace the Alaskan Way Viaduct along the Seattle waterfront, is making "slow, methodical progress," according to this article. The machine bored just 24 feet in 18 days because it works two 10-hour shifts each weekday and needs to stop tunneling every two feet to allow crews to reinforce the tunnel with steel rings, according to the Washington State Department of Transportation. The machine will eventually average 6 feet of digging per day.

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KING-TV (Seattle)

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