Seattle Tunnel Partners (STP) is preparing to resume tunnelling on the Alaskan Way Viaduct replacement project with testing of the stalled tunnel boring machine’s (TBM) cutterhead underway.
Last week, STP began rotating the cutterhead a few degrees at a time, stopping periodically to take measurements before completing a full rotation.
Yesterday, the crew marked the first sustained rotation of the cutterhead since the machine broke through the southern wall of the access pit on 19 February.
STP has indicated that it will now rotate the cutterhead in both directions for about one hour at a time. Watch a short video of the cutterhead rotating below:
During the next phase of work, STP will backfill the access pit with sand and gravel to prepare the TBM for tunnelling.
The machine is expected to resume tunnelling on 23 December.