What's Blocking Seattle's Tunnel-Boring Behemoth?

Is it a giant rock? What about a sunken ship? Beneath Seattle's waterfront, a mysterious object has halted Bertha, the world's largest tunnel-boring machine. Stumped engineers are unclear on how long a highway tunneling project will be suspended.
Ben Brooks / flickr

"Something unknown, engineers say — and all the more intriguing to many residents for being unknown — has blocked the progress of the biggest-diameter tunnel-boring machine in use on the planet, a high-tech, largely automated wonder called Bertha," reports Kirk Johnson. "At five stories high with a crew of 20, the cigar-shaped behemoth was grinding away underground on a two-mile-long, $3.1 billion highway tunnel under the city’s waterfront on Dec. 6 when it encountered something in its path that managers still simply refer to as 'the object.'"

Among the guesses offered by engineers, historians and visitors to a museum for the tunnel project include: a buried train engine, a giant boulder, a famous shipwreck, and Prohibition era "Bootlegger stuff".

"[Chris Dixon, the project manager at Seattle Tunnel Partners, the construction contractor] said that efforts to drain water and reduce pressure at the drill head, with a series of bore holes pushed down in recent days, could allow workers to get safe access to the blocked site as early as Friday." 

Full Story: Under Seattle, a Big Object Blocks Bertha. What Is It?


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