The machine boring the new State Route 99 tunnel under Seattle may not get back to work until the end of March 2015 while efforts continue to repair Bertha.

The Washington State Department of Transportation said Monday that, according to design contractor Seattle Tunnel Partners, the new target date to open the tunnel will be November 2016. That still falls within the deadline of when WSDOT wanted the project completed, but is about a year later than the target STP had set.

Bertha has been stuck since December after digging 1,000 feet of the 1.7-mile tunnel. A previous estimate made in February set a target date to resume tunneling for September.

Construction is expected to begin next month on a pit that Seattle Tunnel Partners will use to access and repair Bertha. Excavating the pit is expected to last through September, with repair work beginning in October.

Resuming tunneling will take longer than any of us would have liked, but making these repairs is a significant engineering challenge that must be done safely, said Chris Dixon, Seattle Tunnel Partners project manager.

The seals surround Bertha s main bearing are broken and have to repaired or replaced. WSDOT said a repair plan was expected to be submitted by June 16.

WSDOT said the repair schedule includes contingency time in case STP or Hitachi Zosen Corp., which built Bertha, finds other issues it wants to repair after the cutterhead is removed.

WSDOT said other construction work related to the tunnel will continue regardless of what is happening with Bertha, which includes building the pit where the machine will emerge when it s finished digging along Aurora Avenue North.

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