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." ...

On April 17, Mary the Tunnel Boring Machine emerged through the headwall ... the third of its kind in the U.S. (The other two ...

Suspension of work conditionally lifted allowing tunnel boring machine to move another 160 ... 2016 Digging for Seattle's Highway 99 tunnel has resumed six weeks after a sinkhole prompted the ...

Nejad noted that other tunnel projects in Seattle and Virginia significantly slowed down when the tunnel boring machines encountered unexpected obstructions. "It's a risky job," Nejad said ...