Bertha was a 57.5-foot-diameter (17.5 m) tunnel boring machine built specifically for the Washington State Department of Transportation's (WSDOT) Alaskan Way Viaduct replacement tunnel project in Seattle, Washington, United States.

It was made by Hitachi Zosen Sakai Works in Osaka, Japan, and the machine's assembly was completed in Seattle in June 2013. Tunnel boring began on July 30, 2013, with the machine originally scheduled to complete the tunnel in December 2015.

Bertha was designed and manufactured by Hitachi Zosen Sakai Works of Osaka, Japan, and is the world's largest earth pressure balance tunnel boring machine, at a cutterhead diameter of 57.5 feet (17.5 m) across.

The machine was 326 feet (99 m) long and weighed 6,700 short tons (6,100 t). The machine itself cost $80 million and is owned by Seattle Tunnel Partners, the project contractors.

According to en.wikipedia