Bertha's back on the move after nearly a week of pause. Last Tuesday, tunnel engineers stopped the giant drill to check for adjustment issues and eventually found that it was six inches off tunnel alignment.
Here's more from the Washington State Department of Transportation (WSDOT):
STP designers made a slight change to the tunnel alignment between the machine’s current location and the end of the tunnel drive. Adjustments are common during tunneling, including on this project. STP made a similar adjustment to correct Bertha’s course after the machine mined out of the access pit following repairs.
Engineers also replaced some cutterhead tools while the machine was halted, WSDOT reports.
Bertha is now less than 1,000 feet from its final disassembly pit. The last schedule update from Seattle Tunnel Partners, the state's contractor, has estimated that the tunnel drive will be completed in May.