Final tunnelling stage on Western Harbour Tunnel Project a step closer

The final stage of tunnelling on the Western Harbour Tunnel Project in New South Wales is a step closer to commencing with the largest tunnel boring machines (TBMs) in the Southern Hemisphere set to arrive in Sydney later this year. 

The new 6.5-kilometre road tunnel is expected to open to traffic in 2028 and importantly, it will remain in public hands. 

“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 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,” Minister for Roads Jenny Aitchison said. 

Excavation of two TBM launch chambers is already underway and are expected to be ready in 2026 for the assembly of the massive diggers. The TBMs will be assembled using a 500-tonne crane. 

Once launched, the TBMs will excavate the 1.5-kilometre twin motorway tunnels that will have three lanes in each direction. Tunnelling works will be carried out 24/7 with about 40 people working on them at any one time, taking about one year to complete. 

Each TBM is 102 metres long and 15.7 metres in diameter and weighs 4,350 tonnes. 

From Birchgrove, the TBMs will work under Sydney Harbour – about 50 metres below sea level – towards Waverton. 

Around 13,000 concrete segments that are set to be precast in Western Sydney will line and support this section of the tunnel. 

Meanwhile, TBM cutterheads have been adorned with artwork to honour their namesakes – Aboriginal women Barangaroo and Patyegarang – in a tribute to Sydney’s past as the machines prepare to shape its future. 

Once completed, the Western Harbour Tunnel will seamlessly connect the Rozelle Interchange to the Warringah Freeway near North Sydney, and it will traverse under Sydney Harbour between Birchgrove and Waverton. 

The overall project is being delivered in two stages, with the first stage already completed in February 2025 by John Holland and CPB Contractors. Stage 2, which is currently underway, is being delivered by ACCIONA. 

The Western Harbour Tunnel Project is anticipated to create up to 6,900 full time jobs during its delivery. 

Source: NSW Government – Media Releases; NSW Government – Western Harbour Tunnel (1, 2)