Robbins EPBM breakthrough on Seattle LRT Northgate Link
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13 July 2015: As excavation progresses on the 3.5 miles of twin running tunnels for the 4.2 mile (7km) Northgate light rail extension for Sound Transit in Seattle, it was the Robbins 6.4m diameter EPBM that recorded the second of six breakthroughs for the two TBMs on the project. The other TBM on the contract for the Jay Dee/Coluccio/Michels JV, the Hitachi Zosen EPBM, recorded the first breakthrough in May this year (2015) and is now into the second of the three parallel drives to the University District Station with the final breakthrough for both machines occurring at the University of Washington and programmed for end of the year for the Hitachi machine and by about March 2016 for the Robbins EPBM. Breakthrough of the Robbins EPBM at the Roosevelt Station box completes the longest section of the twin running tunnels at 8,000ft 2,440m with two drives each of about 5,000ft 1.525m left for each machine to complete.

References
Seattle advances its LRT ambitions - TunnelTalk, June 2015
Robbins EPBM away for Seattle Northgate - TunnelTalk, January 2015-07-14
Seattle Northgate Link TBM dedication - TunnelCast, April 2014

Snapshot

Robbins EPBM breakthrough on Seattle LRT Northgate Link

Shani Wallis and Sterling Noren for TunnelCast
Project: Northgate Link LRT, Seattle
Total Cost: US$2.1 billion
Client: Seattle Sound Transit
Contractor: JCM Northlink JV of Jay Dee/Coluccio/Michels
Contract Value: Approximately US$445 million
Contract Scope: Design-bid-build construction of 3.5 miles (5.5km) of twin running tunnels; two open cut station boxes at Roosevelt and University District; the North tunnel portal structure
Interviewed: Rick Capka, Sound Transit
Glen Frank, JCM Northlink JV
Matthew Greger, Robbins
Brian Hagan, Jay Dee
Designer: CH2M Hill and Jacobs Associates
Geotechnical Consultant: Shannon & Wilson
TBMs: Two 6.4m diameter EPBMs – a Robbins EPBM and a Hitachi Zosen machine
Scheduled Opening: 2021