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TBMs launched on Seattle's U-Link May 2011
Paula Wallis, TunnelTalk
The crash of a champagne bottle marked the start of tunneling operations on Seattle's University Light Rail Link to connect the Washington University campus with Capitol Hill and Westlake Center.
  • Senator Murry christens TBMs

    Senator Murry christens TBMs

  • Confetti rains down at launch celebration

    Confetti rains down at launch celebration

Washington Senator Patty Murry, sent the champagne bottle down a zipline to christen the two Herrenknecht EPBMs during the launch celebration Monday, 16 May. "We know that this community needs more transportation options, and this project is going to deliver," said Murry.
Traylor/Frontier-Kemper JV selected the twin machines for the parallel 3km (2-mile) running tunnels for Contract U220 to Capitol Hill. The first machine began its drive on Monday (16 May) from the open-cut station at the University of Washington (UW). The second machine will start about a month later. Together the two EBP machines will drive the north and southbound tunnels from the UW Station to the Capitol Hill Station (Fig 1).
  • TBMs ready to start their drives

    TBMs ready to start their drives

  • Fig 1. Seattle's U-Link tunnel contracts

    Fig 1. Seattle's U-Link tunnel contracts

The technically challenging drive from UW to Capitol Hill includes high cover of up to 310ft (94.5m) and a high water table. The TBMs will also launch into a steep down gradient (4.5%) to get under the Montlake Cut less than the 300ft (100m) into the drive.
A second tunneling contract (U215) will complete the link from Capitol Hill to the Pine Street Stub Tunnel (PSST). Jay Dee/Coluccio/Michels JV selected a 21ft 2in (6.5m) o.d. Hitachi Zosen EPBM to drive both 3,800ft (1.1km) running tunnels. The machine will work south from a working shaft in the Capital Hill station box to a reception shaft adjacent to the PSST, transferring back to Capital Hill to drive the second tunnel. It will progress on a maximum 5% down gradient for the two drives and operate under an expected pressure of about 1.7 bar. The TBM arrived last month and is being assembled on site in preparation for the start of its drive this summer.
References
U-Link prepares to receive its TBMs - TunnelTalk, Mar 2011
Mobilization of Seattle's U-Link extension - TunnelTalk, Jul 2010

           

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