Seattle mega EPBM - TunnelCast

20 December, 2012: It had to be seen to be fully appreciated - the massive rotating cutterhead, shield and backup of the 17.48m diameter EPBM built by Hitachi Zosen for Seattle Tunnel Partners. The largest ever TBM will build the largest ever bored tunnel to replace the elevated Alaskan Way viaduct across the waterfront of Seattle. The TBM was named at an official ceremony at the Hitachi works in Sakai, Japan, attended by representatives of all parties involved in the record breaking project.


Mega EPBM for Seattle tested in Japan

Shani Wallis reporting for TunnelCast
Alaskan Way viaduct replacement tunnel, Seattle
Construction JV:
Seattle Tunnel Partners - STP
Washington State Department of Transportation
Project scope:
World's largest single-tube, double-deck highway tunnel to replace the earthquake damaged Alaskan Way viaduct across the waterfront of Seattle
Tunnel design:
Mega-EPBM, 17.48m o.d., to drive the 2.7km highway tunnel under the streets of downtown Seattle
Segmental lining:
Nine segments and a key in each 600mm thick x 2m wide ring
Start of TBM drive - June 2013
Breakthrough planned for
July 21, 2014