Bertha reaches planned maintenance stop — next move is under Alaskan Way Viaduct
SEATTLE — Bertha, the State Route 99 tunneling machine, reached a planned maintenance stop near Yesler Way on Saturday after successfully mining almost 300 feet during the past three weeks, the Washington State Department of Transportation said Monday.
According to the contractor, Seattle Tunnel Partners, the machine functioned within required operating parameters. STP has now mined a total of 1,560 feet.
- Performing hyperbaric interventions
- Inspecting the cutterhead, main drive unit and screw conveyor
- Replacing cutting tools
- Extending the conveyor belt and the high-voltage cable