Delivery of Sydney’s first new road harbour crossing in almost three decades is powering ahead as it prepares for the beginning of the final stage of tunnelling works.
Crews have completed the construction of massive twin tunnel underground caverns at Birchgrove that will serve as the launch chambers for two of the largest tunnel boring machines (TBMs) in the southern hemisphere, Barangaroo and Patyegarang.
These massive diggers will excavate the 1.5-kilometre underwater section of Western Harbour Tunnel up to 50 metres below sea level towards Waverton.
The two 28-metre-high caverns at Birchgrove, about 230 metres from the edge of Sydney Harbour, are among the largest ever excavated in Australia. Each cavern is big enough to fit 22 Olympic swimming pools or six Emerald-class Sydney Ferries.
“Today, the Minns Labor Government is one step closer to delivering the Western Harbour Tunnel.
“This is a once-in-a-generation project, with the Minns Government on track to deliver Sydney’s third road harbour crossing.
“After 12 years of Liberal-National privatisation, we are building this project as a public asset for the people of NSW.
“These giant caverns are vast enough to fit six Emerald class Sydney ferries each, but one the TBMs are assembled inside them, there will only be around 1-2 metres between each TBM and the launch chamber walls,” Minister for Roads Jenny Aitchison said.
This milestone follows the arrival of the second TBM in Sydney on 21 October, joining its twin that landed in August.
The machines are engineering marvels, each spanning 137 metres and weighing more than 4,300 tonnes – the equivalent of 88 double-decker buses. The twin TBMs will carve a 1.5-kilometre route under Sydney Harbour to the Warringah Freeway at North Sydney.
Over the coming months, workers will assemble the TBMs piece by piece inside the caverns at Birchgrove using a 500-tonne gantry crane. Each machine is comprised of 263 major parts and assembly will take several months to complete.
The TBMs are expected to begin excavating under the harbour in the first half of 2026. Once launched, they will tunnel around the clock, supported by 40 skilled workers per shift, with works expected to take around a year to complete.
Once up and running, Western Harbour Tunnel will provide a seamless 6.5-kilometre connection between the Warringah Freeway and the Rozelle Interchange. Not only will it help reduce congestion, it will also improve travel times and strengthen connections across the city’s north, west and south.
This game-changing infrastructure will deliver travel time savings to motorists as well as reduce traffic on the Western Distributor by 35 per cent, in the Harbour Tunnel by 20 per cent and on the Sydney Harbour Bridge by 17 per cent.
The Western Harbour Tunnel is on track to open to traffic in 2028 and it will remain in public ownership to ensure long-term benefits of this investment stay with the people of New South Wales.
This major project is supporting 7,000 jobs over the life of its construction.
“The scale of this project is absolutely breathtaking. More than 4,800,000 tonnes of material already have been excavated across the Western Harbour Tunnel project to date.
“The Western Harbour Tunnel TBMs are the largest in the Southern Hemisphere and the largest in the world to be assembled underground. The mega-machines were shipped to Australia in 263 pieces, with 125 shipping containers of other components, and our team is now preparing them for launch.
“In a few days, the TBM parts will be loaded onto specialised heavy vehicles and transported into the launch chambers via the City West Link portal.
“The Western Harbour Tunnel is on track to open in 2028 and importantly, will remain in public ownership,” Minister Aitchison said.
Source: NSW Government – Media Centre; NSW Government – Western Harbour Tunnel; Transport for NSW