Sneak peek at TBMs heading deep below Sydney Harbour

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Australia’s biggest TBMs are heading to Sydney to dig the final stage of the Western Harbour Tunnel — the first new harbour road crossing in nearly 30 years.

The Minns Labor Government is getting on with delivering the Western Harbour Tunnel Project, with the largest tunnel boring machines (TBMs) in the Southern Hemisphere set to arrive in Sydney later this year, to excavate the final stage of the first harbour road crossing in almost three decades.

The 6.5 kilometre Tunnel is set to open to traffic in 2028 and importantly, will remain in public hands. These enormous tunnel boring machines will excavate 1.5 kilometres of the twin motorway tunnels with three lanes in each direction.

Once launched tunnelling will be 24/7 with 40 people working on them at any one time.

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The TBMs are expected to take around a year to complete their work.

In a sneak peek, footage of the TBMs rolling off the assembly line shows the extraordinary complexity of these state of the art machines that will link northern, inner western and southern Sydney via the Western Harbour Tunnel.

The mega machines are 102 metres long and 15.7 metres in diameter, each weighing 4,350 tonnes. They will work under Sydney Harbour, between Birchgrove and Waverton, up to 50 metres below sea level.

A 500-tonne crane will be used to assemble the TBMs in their launch chambers deep underground Birchgrove. Around 13,000 concrete segments, set to be precast in Western Sydney, will line and support this section of the tunnel.

The TBM cutterheads are adorned with artwork to honour their namesakes – Aboriginal women Barangaroo and Patyegarang – in a tribute to Sydney’s past as the TBMs prepare to shape its future.

When completed the Western Harbour Tunnel will provide a seamless connection from the Warringah Freeway and North Sydney to WestConnex at Rozelle Interchange.

For more information visit the Western Harbour Tunnel web page.

Fast facts

Using Western Harbour Tunnel will save drivers:

  • up to 20 minutes from Sydney Olympic Park to North Sydney
  • up to 20 minutes from Leichhardt to North Sydney
  • up to 15 minutes from North Sydney to Sydney Kingsford Smith Airport.

Western Harbour Tunnel will reduce traffic:

  • on the Western Distributor by 35 per cent
  • the Sydney Harbour Tunnel by 20 per cent
  • the Sydney Harbour Bridge by 17 per cent.

Minister for Roads Jenny Aitchison said:

“The Minns Labor Government is getting on with projects that are transforming our city and delivering the infrastructure our community needs.

“These magnificent machines are going to deliver on the Future Sydney vision by carving out our second under-harbour road crossing.

“These are the largest TBMs in the Southern Hemisphere – which gives you a sense of the magnitude of this project that will revolutionise the way our city moves.

“Three whole Sydney Metro tunnels could fit within the diameter of the Western Harbour Tunnel, and each TBM is around the same weight as four Freshwater ferries.

“When complete, the Western Harbour Tunnel will link the northside and city, inner west and airport while taking pressure off the Harbour Bridge and Tunnel, Anzac Bridge and Western Distributor.”

Source: NSW Governement 2025 Media Release

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