First tunnel boring machine on its way to Sydney Metro

Sydney is set to receive the first of its five mega tunnel boring machines (TBMs) to deliver the next stage of the Sydney Metro.

The borer is around 150 metres long and specifically designed to cut through the hard sandstone that makes up a significant portion of the city’s geology.

Sydney is set to receive the first of its five mega tunnel boring machines (TBMs) to deliver the next stage of the Sydney Metro.
Image: Sydney Metro

The TBM will launch at Marrickville later this year and begin tunnelling towards the new Waterloo Station, then under the Sydney CBS via new metro stations at Central, Pitt Street and Martin Place, before finishing at Barangaroo.

Together with the other TBMs, 15.5 kilometres of twin metro railway tunnels will be delivered from Chatswood to Sydenham, including under the Sydney harbour.

Two TBMs will dig around 8.1 kilometres from Marrickville to Barangaroo, while two will cut 6.2 kilometres from Chatswood to Blues Point. The fifth borer has been specifically designed to deliver around 1 kilometres of tunnels under the Sydney Harbour.

The machines dig and line the tunnels as they go to help deliver the Sydney Metro as quickly as possible, tunnelling around 120 metres a week on average.

It creates a tunnel by simultaneously excavating a 1.7 metres section of rock and installing concrete segments to form a ring that will become the tunnel lining.

The TBM took six months to build and has been tested to ensure it meets all of the safety and technical specifications needed for the job.

Each TBM are around 30 metres longer than the four machines used to build the twin 15 kilometres Sydney Metro Northwest tunnels. The cutterhead has 38 hardened steel cutters, which weigh up to 400 kilograms each, which will need to be replaced about every one to two weeks due to the forces of tunnelling.

The machine will be delivered in eight different shipping containers, as well as 23 pieces that are too big to fit and have to be transported individually.


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