Connecting state and local government leaders

A Tough 4-Year Journey for the World’s Largest Tunnel Boring Machine

Bertha, which launched as the world's largest tunnel-boring machine, crashes through its concrete finish line on April 4.

Bertha, which launched as the world's largest tunnel-boring machine, crashes through its concrete finish line on April 4. Courtesy WSDOT

 

Connecting state and local government leaders

Watch Bertha crash through the concrete finish line and the challenging 9,270-foot journey under Seattle to get there.

SEATTLE — It wasn’t supposed to take this long, but “Bertha,” which launched as the world’s largest tunnel-boring machine in July 2013, finally emerged last week in a concrete pit a few blocks from the Space Needle after its two-mile journey under the center of the Pacific Northwest’s largest city.

While the new tolled tunnel and connecting roadways replacing the Alaskan Way Viaduct—the aging seismically vulnerable double-decker highway that carries State Route 99 along Seattle’s central waterfront—won’t open for another two years, the completion of Bertha’s tunneling was a momentous occasion. The toughest part of the multi-billion dollar project is over.

CONTINUE: Click through our review of Bertha's difficult journey and what's left to be done. 

Michael Grass is Executive Editor of Government Executive's Route Fifty and is based in Seattle.

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