Planning approval has been granted for Sydney Metro to deliver the 3.5km twin tunnels from The Bays into the heart of the Sydney CBD, under Johnstons Bay and Darling Harbour, and start excavation on Pyrmont and Hunter Street stations.

Starting at The Bays, tunnel boring machines will cross under the harbour, alongside Anzac Bridge, before heading to the new Pyrmont Station, then under Darling Harbour before reaching Hunter Street Station in the Sydney CBD.

This will be the second time mega tunnel boring machines will dig under the iconic harbour and the finished metro line will mean a second under-harbour rail crossing.

This is the final tunnel section for the new 24km metro line that will double rail capacity between Greater Parramatta and the Sydney CBD.

Two major tunnelling contracts have already been awarded for tunnelling between Westmead and The Bays, with tunnel boring machines planned to be in the ground before the end of the year.

The last tunnelling contract for the final section of the tunnel between The Bays and Sydney CBD will be awarded by the end of the year.

Construction started on Sydney Metro West in 2020, with the project on track to be completed by 2030. In 2030, Sydney will have a network of four metro lines, 46 stations and 113km of new metro rail.