Western Harbour Tunnel is a major transport infrastructure project that will make it easier, faster and safer to travel around Sydney.

The project uses Tunnel Boring Machines  that are among the largest in the Southern Hemisphere, each weighing over 4,350 tonnes and operating 50 metres below sea level.

Design changes introduced by ACCIONA created a construction solution that better balances environmental and community impacts with construction capabilities.

About the project

The Western Harbour Tunnel is a new road crossing beneath Sydney Harbour, separate from the existing Sydney Harbour Tunnel that opened in 1992. ACCIONA is delivering Stage 2 for Transport for NSW.

Western Harbour Tunnel will see a new motorway built underneath Sydney Harbour to connect North Sydney to Rozelle, bypassing the CBD. Stage 2 includes connections from Stage 1 at Cove Street, Birchgrove, to the Warringah Freeway near North Sydney, tunnelling under Sydney Harbour and the complete tunnel fit-out.

Stage 2 includes connections from Stage 1 at Cove Street, Birchgrove, to the Warringah Freeway near North Sydney, tunnelling under Sydney Harbour and the complete tunnel fit-out.

Transport for NSW awarded the Western Harbour Tunnel Stage 2 contract to ACCIONA in December 2022.

Western Harbour Tunnel is a major transport infrastructure project that will make it easier, faster and safer to travel around Sydney.

The project uses Tunnel Boring Machines that are among the largest in the Southern Hemisphere, each weighing over 4,350 tonnes and operating 50 metres below sea level.

Design changes introduced by ACCIONA created a construction solution that better balances environmental and community impacts with construction capabilities.

Construction progress

Stage 2 runs from Birchgrove, beneath Sydney Harbour, to the Warringah Freeway at Cammeray. Our scope covers the twin three-lane tunnels along that section and the mechanical and electrical fit-out of the tunnel end to end.

Two tunnelling methods
The northern section, between Cammeray and Waverton, is excavated using roadheaders working from the Warringah Freeway. Each roadheader removes up to 1,000 tonnes of sandstone a day. Working with Transport for NSW, our team trialled a remote-controlled roadheader that allows operators to work well back from the rock face. A separate roadheader started from Ridge Street in North Sydney to form the future Falcon Street off-ramp.

Beneath the harbour, two slurry tunnel boring machines excavate the final 1.5 kilometres between Birchgrove and Waverton. TBM Patyegarang launched in July 2026 and Barangaroo followed in August, both from caverns 44.7 metres below Birchgrove Oval. At 15.7 metres in diameter and 4,350 tonnes each, they are the largest tunnel boring machines ever assembled underground and the largest used in the Southern Hemisphere. As they advance they install around 13,000 pre-cast concrete segments, manufactured at a dedicated facility at Emu Plains in Western Sydney.

Where we are now

Tunnelling is underway on both drives beneath Sydney Harbour.

Once tunnelling is complete, the fit-out installs the mechanical and electrical systems the tunnel runs on: ventilation, fire safety, lighting, signage and traffic control. The Western Harbour Tunnel will remain in public ownership.

Last updated: September 2026