The Western Harbour Tunnel project has reached another major milestone, with its second tunnel boring machine (TBM) now carving a path towards Sydney Harbour.

Launched 44.7 metres below Birchgrove Oval, tunnel boring machine Barangaroo has begun excavating the final section of the twin motorway tunnels between Birchgrove and Waverton.

Barangaroo joins sister TBM, Patyegarang, which started tunnelling last month.

Together the pair will excavate the final 1.5 kilometres beneath the harbour and complete the last stage of tunnelling for the 6.5-kilometre Western Harbour Tunnel.

At 15.7 metres in diameter and weighing 4,350 tonnes each, the TBMs are the largest ever assembled underground, and the largest to be used in the Southern Hemisphere.

As they advance, they will install around 13,000 pre-cast concrete segments and 1300, 20-tonne culverts manufactured at a dedicated facility in Emu Plains.

During the launch process, Barangaroo will construct the first three tunnel rings, each using ten of the 15-tonne segments, before pushing through the launch chamber wall and starting her journey.

Named after prominent Aboriginal women and adorned with Indigenous artwork, Patyegarang and Barangaroo will operate around the clock and reach depths of up to 50 metres below sea level. Around 40 20 workers will operate each machine at any one time.

The tunnelling comes as another key milestone, the Berry St on-ramp in North Sydney, on the other side of the harbour, nears completion.

The future connection will link motorists to WestConnex via the Rozelle Interchange, bringing the project another step closer to transforming travel across Sydney.

Mechanical and electrical fit out is progressing, including lighting, traffic monitoring cameras and signage that will support the tunnel’s safe operation when it opens.

The Western Harbour Tunnel remains on track to open to traffic in 2028 and will help deliver faster, safer and more reliable journeys across the city, by-passing the CBD.

You can track the TBMs progress here at Transport for NSW – Western Harbour Tunnel TBM Tracker.