Inside the world’s largest tunnel boring machine.

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Inside the world’s largest tunnel boring machine (TBM).

“Bertha,” as it’s known, is the world’s largest TBM and will spend the next 14 months boring a 1.7 mile (2.7 km) tunnel under the city as part of a US$1.2 billion project to replace a viaduct damaged in a 2001 earthquake.



  • R. Cotour


  • Pzatchok

    I wonder if they hit a huge quartz pocket.

    Some quartz is dang close to diamond hardness. And that is all I can think of that would dull those teeth up fast enough to stop one of those.

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