Dive Brief:
- The beleaguered $2.1 billion tunnel boring operation for the $3.14 billion Alaskan Way Viaduct project in Seattle is now 50% complete, according to the Seattle Times.
- Bertha, the nickname for the project tunnel-boring machine (TBM), has managed to dig 4,662 feet of the 9,270-foot route to its South Lake Union target,
- The tunnel, a replacement for the Alaskan Way Viaduct that was damaged by an earthquake in 2001, was originally scheduled to open late last year, but an April 2014 Bertha breakdown, along with other delays, has forced the Washington State Department of Transportation to reschedule the date of completion to 2019.
Dive Insight:
Contractor Seattle Tunnel Partners (STP) — a joint venture including New York-based Dragados USA and California-based Tutor Perini — currently has an outstanding change order with the WSDOT for costs related to Bertha's collision with an underground steel plate. STP maintains that the state did not inform them about the existence of the plate, but state transportation officials have disputed that assertion and filed a $78 million claim with project insurers to recoup additional costs. WSDOT also filed a separate suit against STP. In July, the WSDOT notified state lawmakers of schedule delays and said the project was on track to cost $223 million more than originally planned.
It took repair crews two years to get Bertha up and running in December 2015. Shortly after that, however, WSDOT and Gov. Jay Inslee stopped all tunneling operations after a sinkhole formed over Bertha. In addition, a barge carrying soil excavated from the site tipped over and dumped its load into the water next to where Bertha was tunneling, causing what WSDOT characterized as a hazard to job site staff and the public.
STP filled the sinkhole with concrete and said a study showed that the sinkhole was from "a pre-existing void, a ground loss in the face of the (tunnel-boring machine), or a combination of both." The WSDOT and the governor's office "conditionally lifted" the stop-work order in February, more than one month after the sinkhole and barge episodes. The state permitted operations to continue after receiving a soil monitoring and removal plan from STP, as well as requiring that all future excavated soil be trucked from the site rather than removed by barge.