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Australia is building 10 kilometers of tunnels up to 58 meters below Brisbane — two giant machines weighing 1,350 tons drilled beneath the river and the city center without anyone on the surface noticing
The Cross River Rail is the largest infrastructure project in the history of Queensland, Australia. According to the official project website, the work consists of a new 10.2-kilometer railway line that includes 5.9 kilometers of twin tunnels excavated beneath the center of Brisbane.
Additionally, the Brisbane tunnel houses four new underground stations — Boggo Road, Woolloongabba, Albert Street, and Roma Street — that will transform urban transport in one of the fastest-growing cities in Australia.
At its deepest point, the tunnel boring machines reached 58 meters below the surface at Kangaroo Point and 42 meters below the bed of the Brisbane River.
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Therefore, while the residents of Brisbane walked the streets, shopped, and went to work, two giant machines were silently drilling beneath their feet.
Two machines weighing 1,350 tons each — and 165 meters long
As reported by the International Railway Journal, the project utilized two TBMs (Tunnel Boring Machines) named Else and Merle — tributes to pioneering women from Queensland.
Indeed, each machine weighs 1,350 tons and measures 165 meters in length — almost two football fields lined up. In practice, they are mobile factories that excavate, line, and consolidate the tunnel in a single continuous process.
The TBM Else completed its 294-day journey beneath the Brisbane River and the city center. Consequently, engineers celebrated the breakthrough — the moment when the machine emerges on the other side of the tunnel — as one of the most significant milestones in Australian engineering.
Just as India drilled 14 km through the Himalayas, Australia chose to tackle the complexity of digging beneath a living, functioning city.
Excavating beneath a city is different from drilling through mountains
Compared to tunnels in mountains, excavating beneath a metropolis presents unique challenges. Especially because above the TBMs were buildings, foundations, sewer networks, power cables, gas pipelines, and even archaeological remains.
In this regard, engineers used vibration sensors installed in buildings on the surface to monitor in real-time any movement caused by the excavation below.
Moreover, the soil in Brisbane varies between soft clay, sandstone, and hard rock — requiring the TBMs to constantly adjust their speed and cutting pressure.
To give an idea, when the machine passed beneath the Brisbane River, the pressure of the water above was so intense that any failure in the tunnel’s sealing could cause a catastrophic flood.
Still, no building suffered damage, and no resident reported noticeable vibrations during the 294 days of excavation.
Four underground stations that will transform Brisbane’s transport
Equally impressive is the construction of the four underground stations. According to the official project, each station is being excavated like a giant cave beneath the city center.
The Albert Street station, for example, will be directly below one of the busiest blocks in Brisbane. However, passengers will descend escalators to modern platforms dozens of meters deep.
Thus, Brisbane will have an underground metro system for the first time in its history — a technological leap for a city that until now relied exclusively on surface trains.
From A$ 5 billion to A$ 10 billion — the cost of the Brisbane tunnel has nearly doubled
Despite this, the project faced serious cost and schedule issues. According to Wikipedia, the original budget was A$ 5.4 billion. However, the total cost has already exceeded A$ 10.5 billion — almost double.
Furthermore, labor strikes and construction delays pushed the opening date from 2026 to 2029.
On the other hand, project advocates argue that the long-term impact justifies the cost: the new line will reduce congestion in downtown Brisbane, create an alternative to surface traffic, and connect neighborhoods that previously required transfers.
In comparison, Brazil has 14,000 stalled infrastructure projects that have cost R$ 9 billion without delivering results. The Brisbane tunnel, even with doubled costs, is being completed.
Brisbane in 2029 will be a different city beneath the surface
According to projections from the Queensland government, when the Cross River Rail becomes operational, Brisbane’s rail capacity will increase by 30%. Experts say this should remove thousands of cars from the streets daily.
In practice, residents from southern and northern suburbs will be able to cross the city center without changing trains — something impossible in the current system.
In summary, beneath Brisbane lies a parallel world under construction: tunnels, stations, platforms, and tracks that no one sees from the surface.
To put it in perspective, the total length of the Brisbane tunnels is equivalent to more than 100 city blocks. If laid out in a straight line on the surface, the tunnels would stretch from Copacabana beach to Maracanã in Rio de Janeiro.
The tunnels were also designed to withstand surface flooding without compromising the system. Brisbane experienced historic floods in 2011 and 2022, and engineers built barriers and drainage systems specifically to protect the underground infrastructure.
At the same time, the ventilation of the tunnels was designed to recycle the internal air every 3 minutes, maintaining temperature and air quality comfortable for passengers even on the hottest days of the Australian summer.
Should Brazilian cities like São Paulo and Rio — which suffer from chronic congestion — look to Brisbane’s model and invest in deep underground metros?
Finally, the Cross River Rail shows that it is possible to build transformative infrastructure beneath an entire city without residents noticing — as long as there is cutting-edge engineering, investment, and political will. However, the doubled costs and 3-year delays also remind us that megaprojects rarely go as planned.
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