Facts about the Sydney Metro stage two

WHAT IS INVOLVED IN SYDNEY METRO STAGE TWO

* Tunnelling under Sydney Harbour will construct twin 15.5km metro rail tunnels from Chatswood to Sydenham

* Excavation and civil works for six new metro railway stations at Crows Nest, North Sydney, Barangaroo, Martin Place, Pitt Street and Waterloo

* The first tunnel boring machine will be in the ground by the end of next year

* Four double-shield, hard rock, gripper type tunnel boring machines and one specialised machine for tunnelling under Sydney Harbour will be used

* Stage two works will include an upgrade of the T3 Bankstown Line from Sydenham to Bankstown to metro standards

* The under-harbour tunnel boring machine technology balances the pressure between the machine and the ground in front of it which will help control the excavation process

* Crushed rock will be removed by barges for the excavation work at Blues Point, Barangaroo and under Sydney Harbour

* Stage two of Sydney Metro is expected to open in 2024