In THIS city, trains run at the speed of a cheetah, not above water, but below it, you have to descend 11 floors to travel in this train

If you want to see a train running underwater, you just need to head to Kolkata. Here, the metro train runs beneath the Hooghly River.

Kolkata underwater metro: You may have seen trains running over rivers and even the sea (at Rameshwaram). But if you’ve ever seen a train underwater, talking to the air, most people would be baffled. You may have the chance to witness it. This feat is happening not just elsewhere, but in India, where the first train is running in an underwater tunnel.

In Kolkata, the metro runs through an underwater tunnel built beneath the Hooghly River. This tunnel connects the Esplanade on the east bank of the Hooghly River and the Howrah Maidan on the west bank. The tunnel is approximately 33 meters below ground level, equivalent to an 11-story building. The total distance from Howrah to Esplanade is 4.8 kilometers, with a half-kilometer tunnel built beneath the river. It takes approximately one minute to cross this distance. This tunnel was built to last 120 years.

Underwater tunnel built for the first time in the country

The underwater tunnel, built beneath the Hooghly River, was the first such tunnel in the country. This posed significant challenges in its construction. It required a machine capable of withstanding the pressure of water from above and preventing water from entering during construction. Although tunnels have been built in several cities across the country, this one had to be built underwater, so it couldn’t be done with a standard TBM.

Machine designed for digging

The TBM for tunneling under the river was designed in Germany. Its unique feature was that it cut through the soil while simultaneously sealing the surrounding area. Even if water entered during excavation, the completed tunnel would not be damaged.

Water will never enter the tunnel

Special technology has been used to ensure that water never enters the tunnel. For the first time, hydrophilic gaskets have been used in the joints, which expand 10 times upon contact with water, meaning it will become even more waterproof than before. The underwater tunnel is 520 meters long and 6 meters high.

The project was part of the 1971 Master Plan, but no development took place at that time. Following the success of the Delhi Metro, it received the green light in 2008, and the underwater tunnel was completed by 2025.