Bertha is getting ready to dig the final 1,000 feet of Seattle's Alaskan Way Viaduct replacement tunnel.

Seattle Tunnel Partners (STP) said they temporarily stopped mining on Tuesday for maintenance to prepare Bertha for the final stretch.

While verifying Bertha's position along the route, workers discovered the tunnel boring machine might be several inches off the tunnel alignment.

STP said it is conducting additional survey work and will make adjustments as needed to complete the tunnel drive. Officials said those types of adjustments are common during tunneling. They said similar adjustments were made to correct Bertha's course when crews mined out of the pit that was used to access and repair the machine.

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