Big Bertha, the tunnel boring machine of Washington State Department


Bertha is a tunnel boring machine built specifically for the Washington State Department of Transportation’s Alaskan Way Viaduct replacement tunnel project in Seattle. Bertha has to build the SR99 tunnel under downtown of Seattle, in order to replace the old viaduct “Alaskan Wayâ€. After some moments of pause for machine trouble and maintenance, Bertha is rolling again.

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