Forming part of the US$1.43bn Central Tunnelling Package awarded in July to Acciona Ferrovial JV, the TBMs will bore 11km twin tunnels from The Bays to Sydney Olympic Park. Project owner Sydney Metro expects the first of the machines “to be in the ground” before the end of 2022.

The double-shield, hard rock, gripper-type TBMs will excavate through sandstone and shale, and are expected to advance at an average rate of 200m/wk. To be operated by a crew of 15, the machines are the first of six that will bore the 24km of tunnels from Sydney CBD to Parramatta.

Lessons learnt from recently building more than 30km of tunnels (Sydney Metro Northwest and City & Southwest projects) will be applied to the design of the TBMs.