Bertha Tunnel Boring Machine Halted, May Be Off Course 'Several Inches'

SEATTLE, WA - A few weeks after it reached a pretty big milestone, Berth, the SR 99 tunnel boring machine, has been halted underneath Seattle because it may be off course.

The Washington State Department of Transportation announced this week that Bertha stopped drilling on Tuesday so that crews can verify its position. Bertha "may be several inches off" of alignment, WSDOT reported in a release.

Right now, Bertha is just under 1,000 feet from the drilling finish line near the Seattle Center. This last stretch is the final leg of Bertha's nearly 10,000-foot-long journey underneath Seattle.

But the state is advising Bertha-watchers - either fans or detractors - not to freak out. The state says that Bertha will be back to mining next week, and that it's "routine" for crews to perform maintenance on the machine.

Barring further delays, Bertha should be done tunneling in May.

In early February, Bertha passed underneath the Battery Street Tunnel, about 1,600 feet from the finish line - that's about as far as three Space Needles stacked end to end. Bertha drilled about 930 feet in February alone, nearly double the amount it drilled in January.

Image via Washington State Department of Transportation