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Bertha takes maintenance break after 3,088 feet

As of this week, Bertha has tunneled 3,088 feet, most of which has been accomplished in the past eight weeks

Bertha has stopped, but at least this time it was a planned break.

Things have run fairly smoothly for the tunnel boring machine beneath Seattle since it restarted in February following a sinkhole. Even the Alaskan Way Viaduct closure ended up being way smoother than anticipated.

As of this week, Bertha has tunneled 3,088 feet, most of which has been accomplished in the past eight weeks. At this point, nearly one-third of the way there, it’s time for a scheduled maintenance break.

It’s a reality faced by all car owners: Every few thousand miles, it’s time for an oil change. The same principle applies to tunneling machines, which experience normal wear and tear as they grind their way through the earth.

And so, after more than 1,500 feet of tunneling since their last pit stop, Seattle Tunnel Partners crews are set to begin regular maintenance on the massive machine. The front end of the cutterhead is now located approximately 120 feet beneath Spring Street, near Post Avenue. It will remain at that location for planed inspections and maintenance that are expected to last several weeks, though the duration of the stop will ultimately depend on the extent of the maintenance needs.

Bertha is currently in Zone 4, past the foundation of the northbound SR 99 and well underneath Downtown nearing Seneca Street. Crews will assess what Bertha needs in order to figure out how long this stoppage lasts but we’ll probably know more by early next week.