Five tunnel boring machines (TBMs) have been ordered to help build Sydney Metro’s new twin railway tunnels, making the project the first in Australian history where five TBMs have worked on a transport infrastructure project.
Two TBMs will dig 6.2km from Chatswood to the edge of Sydney Harbour; two will travel 8.1km from Marrickville to Barangaroo; and a specialised TBM will build the twin tunnels under Sydney Harbour.
The TBMs are:
- Four double-shield, hard rock, gripper-type TBMs designed to excavate through sandstone and shale
- One specialised mixed-shield TBM which will use slurry technology to tunnel under Sydney Harbour
About 93 per cent of the tunnelling will be through sandstone as the five TBMs excavate the 15.5km tunnels.
The first of the five mega borers will be in the ground before the end of 2018, delivering the new city-shaping railway system for Sydney as quickly as possible.