Mega EPBM arrives in Seattle 02 Apr 2013
TunnelTalk reporting
After two weeks on the high seas, the ship carrying components of the 17.48m diameter EPBM for the Alaskan Way viaduct replacement tunnel in Seattle arrived safely from the Hitachi Zosen factory in Japan and unloading began without delay.
Precious cargo arrives after a 5,000 mile sea journey

Precious cargo arrives after a 5,000 mile sea journey

With little space to spare on the deck, the US$80 million machine was shipped as 41 major components, the largest weighing about 900 tons. First off the ship and onto the storage area ahead of assembly in the launch bay was the 17.48m diameter cutterhead, which features man accessible areas to allow replacement of tools at atmospheric pressure.
The huge EPBM, built in Japan by Hitachi Zosen is owned by Seattle Tunnel Partners (STP), the design-build JV of Dragados, Spain and Tutor Perini, USA, engaged by the Washington State Department of Transportation to build the new 2.7km long double-deck highway tunnel under the streets of Seattle to replace the earthquake-vulnerable elevated highway viaduct that runs along the city's waterfront.
Giant 17.48m diameter cutterhead unloaded

Giant 17.48m diameter cutterhead unloaded

Concurrent with manufacture of the world's largest TBM in Japan, STP crews in Seattle advanced construction of the 24m deep launch pit into which the machine components will be reassembled and set off on its 2.7km long journey in two to three months time. Following rigorous tests in Japan, the mighty machine named Bertha, passed all the tests and will officially become the property of STP once its has successfully tunneled about 1,000ft (300m).
In addition to building the launch pit, crews in Seattle are preparing the surrounding area for tunneling, which includes strengthening the soil and building protected underground work areas along the initial section of the tunnel route so crews can perform scheduled inspections of the machine before it begins tunneling beneath the city.
Work is also under way near the north end of the Battery Street Tunnel to prepare the area where the TBM will emerge at the end of tunneling.
  • Construction of the open cut approach to the bored tunnel starter wall

    Construction of the open cut approach to the bored tunnel starter wall

  • Construction of the TBM launch bay

    Construction of the TBM launch bay

Arrival of the machine in Seattle is another major milestone of this record-setting tunneling project. TunnelTalk will continue to follow progress and publish both articles and video reports of its advance.
VIDEO: Mega-TBM assembled and tested in Japan - TunnelCast, December 2012
Technical parameters of Seattle's mega EPBM - TunnelTech, December 2012
VIDEO: Alaskan Way bored tunnel alignment - TunnelCast, October 2010
Keeping Seattle safe on Alaskan Way TBM drive - TunnelTalk, February 2012
Alaskan Way contract signed - TunnelTalk, January 2011

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