Sydney Metro: start of city tunnelling

Tunnelling started on 17 October 2018 to deliver twin new metro railway tunnels below the centre of Sydney and deep under Sydney Harbour.

Tunnel boring machine (TBM) Nancy is one of the five mega borers which will build 31 kilometres of tunnels between Marrickville and Chatswood.

The TBM has been named Nancy in honour of transport pioneer Nancy Bird Walton OBE.

Sydney Metro acting chief executive Tom Gellibrand and Terry Sleiman, the project director for tunnellers John Holland CPB Ghella, outline the massive tunnelling task.

Nancy and another TBM will tunnel 8.1 kilometres from Marrickville to the new Sydney Metro station sites at Waterloo, Central, Pitt Street, Martin Place and on to Barangaroo, where they will be removed from deep underground.

The TBMs are about 150 metres long – that’s longer than two Airbus A380s – and specially designed for Sydney’s geology to cut through hard sandstone.

The five TBMs will excavate 5.9 million tonnes of rock – enough to fill about 940 Olympic swimming pools.

This is the first time in Australian history that five TBMs have worked on a transport infrastructure project.

The borers are underground tunnelling factories, mechanical worms designed to dig and line the tunnels as they go so that Sydney Metro can be delivered as quickly as possible.

Nancy is specially designed to cut through sandstone and shale and will tunnel an average of 120 metres a week.

Two TBMs will also dig 6.2 kilometres from Chatswood to the edge of Sydney Harbour. A fifth machine has been specially designed to deliver the twin tunnels under Sydney Harbour.

It is traditional to give a female name to all machines which work underground, because workers look to Saint Barbara for protection.

Nancy Bird Walton OBE was an Australian pioneer aviator, the first female pilot in the Commonwealth to carry passengers and the founder of the Australian Women Pilots' Association. Yesterday (16 October 2018) would have been Nancy Bird-Walton’s 103rd birthday.

This project opens in 2024 and will extend Sydney Metro from the city’s north west, where services start in 2019.

In 2024 Sydney will have 31 metro stations and a new 66 kilometre standalone metro railway.