Bertha is back up and boring underneath downtown Seattle

Bertha is back up and running after a maintenance stop 200 feet below the surface of downtown Seattle.

Bertha is under these downtown Seattle buildings

The boring machine stopped on Oct. 22 so crews could inspect the cutterhead and replace any worn down tools. About 100 such tools were replaced, out of 700. This is the kind of high-pressure stop that requires crews to go into hyperbaric conditions.

Though Bertha started back up Monday, its distance hasn’t changed much from the last report — it has bored 5,085 feet and crews have put in place 774 rings. It is currently about 200 feet below First Avenue and will soon pass under Stewart Street.

Once it reaches Stewart Street, Bertha will move from zone 6 to zone 7 — out of 10 zones. It has already passed its halfway mark.

Follow @https://twitter.com/DyerOxley