The first TBM for Sydney’s Western Harbour Tunnel project is due to be launched in the next few days.
TBM Patyegarang will soon begin her journey 44.7m below Birchgrove Oval, under Sydney’s iconic harbour towards Waverton, following final testing over the weekend.
Patyegarang and her sister TBM, Barangaroo, are the largest TBMs in the Southern Hemisphere and the largest to have ever been assembled underground. The CREG-manufactured machines each have a 15.7m diameter and weigh 4,350 tonnes. They will line the tunnels will approximately 13,000 pre-cast concrete segments.
The New South Wales Government says the underground slurry treatment plant is also a record-breaker. The plant can pump up to three million litres of slurry per hour to each boring machine face to keep it stable while it excavates under Sydney Harbour’s soft marine sediments.
The plant is more than 100m long and up to 15m high and is the first slurry treatment plant of this size to have been constructed underground in the world.
The dry spoil will be trucked out of the tunnel via WestConnex for use on other projects.
TBM Barangaroo is 94% complete and is expected to begin tunnelling in around four weeks.
The TBMs will excavate the final 1.5km stretch of the twin motorway tunnels under Sydney Harbour, reaching depths of 50m below sea level. They will operate 24/7 and will have 40 people working on them at any one time.
Overall, excavation is 81.35% complete. The 6.5km Western Harbour Tunnel is set to open to traffic in 2028.
Minister for roads Jenny Aitchison said launching the first TBM was a major milestone for the project.
“This is a major milestone for the Western Harbour Tunnel project, marking the beginning of the final stage of excavation under Sydney Harbour.
“Assembling these mega machines entirely underground has been incredibly complex work and the team is doing a fantastic job,” she said.
“Building and operating the tunnel boring machine’s slurry treatment plant underground is a not only a major win for the local community, but a significant engineering first for Australia and the world.”
The John Holland and CPB joint venture (JHCPB) completed roadheader excavation on Stage 1 in December 2024 and the tunnels were then handed over to the Stage 2 contractor, Acciona.
