TBM Bertha repairs to take 12 months - TunnelCast

April 2014: The recovery schedule to get TBM Bertha restarted on her 2.7km journey under downtown Seattle confirms the main bearing must be replaced and the seal assembly repaired and strengthened. WSDOT's design build contractor, Seattle Tunnel Partners (STP), has begun excavation of a recovery shaft in front of the 17.48m diameter Hitachi Zosen EPBM, and explained that the machine will not be ready to continue its drive until March 2015. STP believes it can still complete construction of the double deck tunnel by the original project due date of 16 November 2016.

Twelve month repair job for TBM Bertha - TunnelTalk, April 2014
Addressing the Bertha bearing seal issues - TunnelTalk, February 2014
WSDOT questions contractor TBM decisions - TunnelTalk, March 2014
TBM Bertha suffers bearing seal failure - TunnelTalk, February 2014
Hyperbaric inspections begin in Seattle - TunnelTalk, January 2014
Investigating the Seattle mega-TBM stoppage - TunnelTalk, January 2014
Dewatering to help deal with stuck Bertha - TunnelTalk, December 2013


TBM Bertha repair strategy

Sterling Noren reporting for TunnelCast
Project: Alaskan Way Viaduct replacement tunnel, Seattle
Contractor: Seattle Tunnel Partners (Dragados/Tutor Perini)
Client: WSDOT
TBM: Hitachi Zosen 17.48m EPBM
Date of breakdown: December 2013
Nature of problem: Machine overheating, initially thought to be as a result of an obstruction (steel well casing)
Diagnosis: Ruptured bearing seals leading to damage to the main bearing
Bearing manufacturer: Rothe Erde of Germany
Replacement bearing: Already manufactured as part of the contract, it is currently located in Osaka, Japan; to be shipped to the jobsite at a future date
Access method: Via a recovery shaft to be excavated ahead of the cutterhead
Revised schedule: Repairs completed by March 2015, with project delivery delayed 12 months from bid date of November 2015
Contract delivery date: November 2016