This is how a tunnel boring machine will burrow a viaduct under Seattle

A portion of Seattle’s Alaskan Way Viaduct is being replaced by a deep tunnel, and the machine purpose-built for the job is the world’s largest tunnel-boring machine TBM, christened “Bertha.” Built by Hitachi Zosen, the 300-foot-long doomsday machine is excavating a 57.5-foot-wide hole for a two-level highway with two lanes in each direction. Bertha has only recently arrived at the Port of Seattle and is still waiting to get off the cargo ship she rode in on.

via This is how a tunnel boring machine will burrow a viaduct under Seattle.

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