May 19, 2017

Tunnel Boring Machine "Bertha" Successfully Completed SR 99 Tunnel Project in Seattle

Osaka, Japan, May 19, 2017—Hitachi Zosen Corporation(TYO:7004) has announced that the Tunnel Boring Machine (TBM) known as “Bertha” has successfully completed mining for the SR 99 Alaskan Way Viaduct Replacement Project in Seattle.



One of the world’s largest TBMs, Bertha was manufactured at Hitachi Zosen Corporation’s Sakai Works in Sakai City, Japan, on behalf of Seattle Tunnel Partners, a joint venture between Dragados USA Inc. and Tutor Perini Corporation.

With a diameter of 17.45 meters and weighing approximately 7,000 tons, Bertha mined a nearly 3 km tunnel just beneath the center of downtown Seattle, reaching its final destination on April 4, 2017.

“Hitachi Zosen is pleased and proud that Bertha has completed mining for the SR 99 Tunnel Project in Seattle,” said Hitachi Zosen USA President Takashi Hayato. “We are excited that the people of Washington State will enjoy the benefits of the deep bore tunnel and the eventual removal of the earthquake-damaged Alaskan Way Viaduct.”

Hitachi Zosen is the world’s leading manufacturer of shield tunneling machines, having supplied  approximately 1,300 machines to clients around the world, including in the United States, Singapore, India, Taiwan, Hong Kong, South Korea and elsewhere. The company has supplied more than 20 large-scale shield tunneling machines such as Bertha that have a diameter of 10 meters or more.