Africa's longest underground tunnel costing £2.6bn with 3 train stations and 10 miles long

A 9.6-mile-long underground tunnel that has revolutionised the infrastructure system in Africa is the longest in the continent. The Gautrain rail tunnel which connects prominent destinations in Gauteng province was built at an estimated cost of $3.6 billion (£2.83 billion).

The engineering marvel connects three key underground stations-Johannesburg Park, Rosebank, and Sandton-providing daily access for thousands of commuters to essential services and bustling economic centres. This underground tunnel is a key part of the 80-kilometre Gautrain rail network, helping people travel quickly between major locations.

Building a tunnel as large as the one used in the Gautrain project took remarkable engineering skill. To carve through the Earth accurately, teams used powerful tunnel boring machines (TBMs) along with traditional drilling and blasting techniques. Keeping the tunnel perfectly aligned was essential for safety and stability, so precision was a top priority from start to finish.

Engineers had to work around tough conditions-like the lack of magnetic fields and the fact that GPS doesn't work underground. Instead, they used advanced laser alignment systems and high-tech surveying tools to guide the construction with incredible accuracy. Thanks to these efforts, the Gautrain tunnel has become a global example of excellence in large-scale infrastructure.

The Gautrain tunnel has seven emergency shafts and safe zones to protect passengers during emergencies. High-tech systems help monitor the tracks and keep trains running smoothly at speeds up to 160 km/h.

Building the tunnel was a big engineering challenge, finished in stages between 2010 and 2012.

By going underground, the Gautrain avoids busy city areas, giving travelers an easy ride between Johannesburg, Pretoria, and OR Tambo International Airport.

Africa hosts a range of long tunnels serving diverse functions-from transporting water to enabling rail and road travel across the continent.

Building these tunnels is no small feat. One of the greatest challenges lies in ensuring that drilling from opposite ends meets with pinpoint accuracy, all while maintaining a clear line of sight.

Conventional tools like compasses fall short due to disrupted magnetic fields, and GPS signals don't penetrate underground.

This forces engineers and construction teams to overcome major hurdles, relying on cutting-edge technologies and meticulous planning to complete these complex underground structures.