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.OverviewBertha was a 57.5-foot-diameter (17.5 m) built specifically for the 's (WSDOT) project in ,. .
The name Bertha, after Seattle's first female mayor, , was chosen by a panel (that included the Governor and Transportation Secretary) from 150 submissions from kindergarten through 12t.
[pdf] A rotary drilling rig is a construction machinesuitable for hole-forming operations in building foundation engineering. It is mainly suitable for sandy soil, cohesive soil, silty soil, fill layer, and silt layer, so.
[pdf] A tractor Borewell Machine is also called tractor mounted water well drillingrig.It combines a tractor with pneumatic water well drilling rig to form well-drilling equipment integrated with a drilling rig an.
[pdf] 
