Tunnelling under Sydney CBD complete for the second phase of Sydney Metro

Tunnelling under Sydney CBD complete for the second phase of Sydney Metro
Tunnelling under Sydney CBD complete for the second phase of Sydney Metro

Four of the five Tunnel Boring Machines working on the second phase of Sydney Metro have completed their runs with TBM Mum Shirl breaking through the southern wall of the Barangaroo station pit over the weekend.

A fifth TBM is still working on completing the short section of tunnel under Port Jackson between Barangaroo and a launch site near Blues Point on the northern shore.

TBMs that began their journey near Sydenham at the southern end of the tunnels have taken 14 months to complete their runs.

Since starting work at Marrickville in November 2018, Mum Shirl took about 14 months to build an 8.1-kilometre tunnel to Barangaroo, cutting through sandstone and shale to excavate more than 821,000 tonnes of rock - enough to fill 126 Olympic swimming pools.

About 29.5km of 31km of twin metro tunnels between Chatswood and Sydenham – or 97 per cent – are now complete with TBM Kathleen now digging under Sydney Harbour to finish her second under-harbour metro tunnel.

TBMs Nancy, Wendy and Mabel finished work late last year.

Sydney Metro/NSW Government

Barangaroo station on Sydney CBD's northwest periphery took two years to excavate and during that time, 460,000 tonnes of rock were removed.

According to an indicative timeline, after tunnel and station pit construction has been completed, the tunnel fit-out phase - the installation of track, emergency egress & walkways, overhead electrical equipment, signalling and communication systems - will run for approximately 2 years.

Thereafter, a testing phase will run for approximately 12 months.

The second phase Sydney Metro City & Southwest project also sees the conversion of existing railway between Sydenham and Bankstown in order for metro services to take over operations of services in the inner southwest of Sydney.

Summertime shutdowns of existing services will occur over several years to convert the line for metro use and the second phase of the entire Sydney Metro project is expected to start taking its first passengers in 2024.

Tunnelling under Sydney CBD complete for the second phase of Sydney Metro
Map of Sydney Metro phases 1 and 2. Image: Wikipedia

The second phase of the first Sydney Metro line precedes other work underway for a second and third line.  The second line dubbed Sydney Metro West, in October last year, had its station locations narrowed down by the NSW Government.

It will add more capacity between Sydney CBD and Parramatta with future-proofing to allow the line's eventual extension westward.  Initial work is expected to start in 2020, tunnelling to start in 2022 and the project is expected to take its first passengers in 2030.

The third line, dubbed Sydney Metro Greater West, will see a line built from St Mary's on the existing T1-Western line southwards to the new Western Sydney International (Nancy-Bird Walton) Airport.

Federal and NSW Government money has been allocated for the Sydney Metro Greater West with construction expected to be completed by the time the new Western Sydney Airport opens in 2026.

Alastair Taylor

Alastair Taylor

Alastair Taylor is a co-founder of Urban.com.au. Now a freelance writer, Alastair focuses on the intersection of public transport, public policy and related impacts on medium and high-density development.

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