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When Seattle decided to replace the Alaskan Way Viaduct — an elevated section of highway that runs between Elliott Bay waterfront and the downtown district — with a tunnel, they hired the world’s largest tunnel borer: a 300-foot long, five stories-high driller named Bertha. Bertha is a very big girl — the 7,000 ton machine needed to be shipped to Seattle in 31 pieces. With a diameter of 57.5 feet, she could easily swallow the world’s second-largest borer, located in Florence, Italy.
World’s Largest Tunneling Machine
