January 2016 was supposed to signify a new beginning for “Bertha,” the world’s largest tunnel-boring machine that now sits under downtown Seattle with its 57.5-ft-dia cutterhead motionless. The ill-fated TBM is idle once again, thanks to a sinkhole.
Designed to bore a 1.7-mile tunnel under downtown Seattle in an effort to replace the seismically vulnerable Alaskan Way Viaduct, the machine started tunneling again in December 2015, after a two-year delay to replace the main bearing, among other fixes. It was halted by Washington Gov. Jay Inslee (D) on Thursday, Jan. 14.