First mega borer arrives for big dig under city centre

The tunnel boring machine (TBM) is about 150 metres long – or longer than two Airbus A380 super jumbos – and specially designed for Sydney’s geology to cut through hard sandstone.

The TBM is arriving at the Marrickville launch site in eight shipping containers and 23 other separate pieces so big they don’t fit into a container – including a 100 tonne cutter head and a 128 tonne section of the round steel tunnelling chamber, each delivered on truck trailers with 68 wheels.

The 1,100 tonne TBM will be assembled and tested before it is launched later this year. It will tunnel to the new Waterloo Station, then continue under the Sydney CBD via new metro station sites at Central, Pitt Street, Martin Place, and on to Barangaroo Station.

Tunnelling will start before the end of the year.

This is the first time in Australian history that five TBMs have worked on a transport infrastructure project, delivering new 15.5 kilometre twin metro railway tunnels from Chatswood to Sydenham, including under Sydney Harbour.

Two TBMs will dig 6.2 kilometres from Chatswood to the edge of Sydney Harbour. Two will travel 8.1 kilometres from Marrickville to Barangaroo. The fifth TBM has been specially designed to deliver twin one kilometre long tunnels under Sydney Harbour.

They are expected to tunnel about 120 metres a week on average.

The five TBMs are part of the $2.81 billion tunnelling contract awarded in June 2017 to the John Holland CPB Ghella joint venture, which contracted world-leading manufacturer Herrenknecht to design, build and deliver the TBMs.