Big Bertha’s close to the deepest point

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The gigantic tunnel boring machine Big Bertha is operating in Seattle and it is reaching the deepest point of its route below of city’s downtown. Big Bertha has completed 60 percent of its 9,270-foot mission and the crews have installed 880 of the project’s 1,426 concrete tunnel rings.

Big Bertha will substitute the seismic ally vulnerable Alaskan Way Viaduct.

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