Five tunnel boring machines have been ordered to build Sydney Metro’s new twin railway tunnels, including deep under Sydney Harbor. The first of the five mega borers will be in the ground before the end of next year, delivering this new city-shaping railway system for Sydney as quickly as possible.
The five tunnel boring machines (TBMs) are part of the $2.81 billion (AUS) tunneling contract awarded in June to the John Holland–CPB–Ghella joint venture, which has contracted Herrenknecht to design, build and deliver the TBMs.
Two TBMs will dig 6.2 km from Chatswood to the edge of Sydney Harbor; two will travel 8.1 km from Marrickville to Barangaroo; and a specialized TBM will build the twin tunnels under Sydney Harbor. This will be the first time in Australian history five TBMs have worked on a transport infrastructure project.
The tunnel builders undertook a global tender inviting world-leading TBM suppliers to participate. These TBMs will be specifically built for the conditions they will meet on this job while we’ve also taken on board design improvements from lessons learned while building the Sydney Metro Northwest tunnels.
The TBMs are: Four double-shield, hard rock, gripper-type TBMs designed to excavate through sandstone and shale; and one specialized mixed-shield TBM, which will use slurry technology to tunnel under Sydney Harbor. About 93 percent of the tunneling will be through sandstone as the five TBMs excavate the 15.5 km tunnels.