Seattle’s Tunneling Machine Bertha Veers Off Course

SEATTLE (AP) — Recent surveys have found that Seattle's new highway tunnel is a few inches off course and digging has stopped until next week while more measurements are made.

Seattle Tunnel Partners project manager Chris Dixon said Wednesday that surveys found the concrete tunnel rings being installed behind the tunnel machine known as Bertha varied "a couple inches" beyond a 6-inch tolerance limit.

The Seattle Times reports more surveys will be done and that a gyroscope is coming from Ohio to increase the precision.

Dixon says if the alignment is off, the necessary course corrections will be made.

Bertha has completed almost 90 percent of the dig from the Sodo area to South Lake Union.

The cutter head is expected to break through to daylight and be removed sometime this spring.