City infrastructure enthusiasts, this one’s for you. After years in the works (the project was initially announced back in 2017) the NSW Government has just ticked off a major milestone in the creation of the Western Harbour Tunnel, the city’s first new road harbour crossing in almost 30 years.
This week, construction crews finished carving out two (huge) underground caverns at Birchgrove. The twin caverns – each large enough to hold 22 Olympic swimming pools or six Emerald-class Sydney ferries – will soon house two colossal tunnel boring machines (TBMs). Together, the machines will burrow a 1.5-kilometre path beneath Sydney Harbour, up to 50 metres below the water’s surface, connecting Birchgrove to Waverton as part of the game-changing Western Harbour Tunnel.
When it opens in 2028, the Western Harbour Tunnel will provide a 6.5-kilometre link between the Warringah Freeway and the Rozelle Interchange – slashing travel times, reducing congestion, and taking pressure off some of Sydney’s busiest roads. According to the NSW Government, Sydneysiders should expect to see a 35 per cent drop in traffic on the Western Distributor, 20 per cent fewer cars in the Harbour Tunnel, and a 17 per cent drop in traffic on the Harbour Bridge.
The stats sound impressive, and the machinery behind it is pretty mind-blowing too. Each TBM is 137 metres long and weighs more than 4,300 tonnes – that’s the equivalent of 88 double-decker buses – making them the largest of their kind in the Southern Hemisphere and the biggest ever assembled underground anywhere in the world. Once they’re fully built (painstakingly assembled from 263 parts apiece), the machines will be fired up in early 2026, tunnelling under the harbour for 24 hours a day with a team of 40 workers per shift to guide their journey. The job of chewing through rock and earth beneath the harbour is expected to take about a year, with the tunnel still on track to open in 2028.
In total, the project is supporting 7,000 jobs and promises to deliver a world-class, (and, crucially, publicly owned) piece of infrastructure that will make getting around Sydney a whole lot more efficient (in terms of traffic, time and tolls).