When North America's largest tunnel-boring machine pushed a 50-ft-long, 8-in.-dia steel pipe seven feet out of the ground on Dec. 3, joint-venture contractor Seattle Tunnel Partners and Washington State Dept. of Transportation officials didn't think much of it.
"Bertha," the 57.5-ft-dia machine, kept churning its state Route 99 tunnel path below Seattle at faster-than-predicted paces. But only for three more days.