Seattle Northgate Link TBM inauguration - TunnelCast

April 2014: At a special commemoration ceremony the refurbished Hitachi Zosen EPBM that will excavate twin running tunnels on the northern section of Seattle Sound Transit’s Northgate light rail extension was unveiled ahead of final pre-launch safety checks. The 6.4m diameter machine, previously used by the same contractor joint venture (Jay Dee/Michaels/Coluccio) for completion of 1.1km of twin running tunnels for Sound Transit’s University Link extension, will launch in June (2014) southwards from the tunnel portal at Northeast 94th Street, all the way through to Washington Station with scheduled maintenance stops at Roosevelt and U-District Stations. The refurbished Robbins machine that will mine the parallel tunnel is scheduled to launch in October 2014. Mining of the main tunnels is expected to take two years to complete, with excavation of the 23 cross passages scheduled to take a further 12 months.

References
Seattle Northgate LRT Link bid result - TunnelTalk, May 2013
Construction management for Northgate LRT - TunnelTalk, November 2012
Seattle pushes on with LRT extensions - TunnelTalk, August 2012
TBMs complete excavation of U-Link extension - TunnelTalk, August 2012

Snapshot

Seattle Northgate Link TBM inauguration

Sterling Noren reporting for TunnelCast
Project: Northgate Link LRT, Seattle
Total Cost: US$2.1 billion
Contractor: JCM Northlink JV (Jay Dee/Collucio/Michaels)
Client: Seattle Sound Transit (SST)
Contract Sum: US$440.3 million
Contract Scope: Design-bid-build construction of 5.5km of twin running tunnels; Roosevelt and Brooklyn (University District) cut and cover stations; North tunnel portal
Designer: Jacobs Associates
Geotechnical Consultant: Shannon & Wilson
TBMs: 2 x 6.4m diameter EPBMs
Drive strategy: The contractor changed the initial strategy of using three machines, to using two plus a back-up machine. The refurbished Hitachi Zosen EPBM launches in June, followed by a refurbished Robbins (being shipped from Singapore) in October. A refurbished Mitsubishi is being held in reserve.
Scheduled Opening: 2021

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