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Testing time for State Route 99 tunneling machine

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Date:  Friday, December 21, 2012

Contact: KaDeena Yerkan, Alaskan Way Viaduct Replacement Program, 206-805-2846, (cell) 206-795-1876 (Seattle)

OSAKA, JAPAN – Last week, the world’s largest-diameter tunneling machine received a name. This week, it received U.S. visitors, as State Route 99 Tunnel Project leaders traveled to Japan to witness testing of the five-story-tall behemoth that will begin tunneling beneath downtown Seattle next summer.

Leaders from the Washington State Department of Transportation and its contractor, Seattle Tunnel Partners, spent Thursday, Dec. 20, at the Sakai Works factory in Osaka, watching major components of the $80 million machine rotate, extend, retract and move. Seattle Tunnel Partners will authorize shipment of the machine, dubbed Bertha, after testing is completed next month. Crews will then prepare the machine for its eventual departure to Seattle.

“This machine is incredibly innovative,” said Linea Laird, WSDOT’s administrator for the Alaskan Way Viaduct Replacement Program. “Using technology like this allows us to create a new highway 99 while keeping the viaduct open to traffic.”

Crews in Japan will spend the early part of next year disassembling Bertha into 41 separate pieces – the largest weighing up to 900 tons – and loading them onto a single ship. After a month-long trip across the Pacific Ocean, Bertha will land at the Port of Seattle’s Terminal 46, to the west of CenturyLink Field. Crews in Seattle will transport the pieces a few hundred yards east to an 80-foot-deep pit where the machine will be reassembled and launched beneath downtown next summer.

“Every last component was designed and built specifically for the soils beneath Seattle and the needs of this project,” said Chris Dixon, Seattle Tunnel Partners project manager, who like Laird attended Thursday’s ceremony. “It’s truly one of a kind.”

Hitachi Zosen Corporation was selected ahead of three other firms to manufacture the machine based on overall technical requirements, support capabilities, price and schedule. Based in Osaka, Japan, the firm has successfully built more than 1,300 tunnel boring machines, a number of them for large-diameter tunnel projects. They supplied the tunnel boring machines for Sound Transit’s Capitol Hill Station to Pine Street segment and the Bay Tunnel near San Francisco, Calif.

Bertha’s size and complexity limited the number of firms that were qualified to manufacture her, Laird said.

“She was built in Japan, but the tunnel project has brought plenty of jobs to Washington,” Laird said. “All you have to do is drive by the construction zone to see how many people this project has put to work in Seattle.”

Seattle Tunnel Partners is a joint venture between Dragados USA and Tutor Perini Corp. Its team includes several local firms, among them Frank Coluccio Construction and HNTB Corp. Nearly 85 percent of STP’s sub-contracts – including contractors, consultants and suppliers – are with firms located in Washington. Construction to replace the viaduct has sustained more than 3,900 jobs this year.

People interested in learning more about Bertha and the tunnel project have a number of options. Photos of the machine and construction in Seattle are posted regularly on Flickr, and WSDOT is documenting Bertha’s journey on Twitter. A 10-foot-long interactive model of Bertha is on display at Milepost 31, the project’s information center in Pioneer Square. For more information about the SR 99 Tunnel Project, visit

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