The country is all set to get its first underwater metro in Kolkata which will pass several feet under the river Hooghly through a tunnel. The first underwater tunnel transportation is complete, while the east-west metro is secluded to be operational by August 2020.



Kolkata metro line 2, also known as the East-West Corridor of the Kolkata is the fast ongoing-transit system which aims to connect Salt Lake in Kolkata along with Howrah bridge which will pass underneath the Hooghly River/Ganga of the state. This metro system would consist of 12 stations from Salt Lake sector V in the east to Howrah Maidan in the west, of which 6 stations would be elevated and the rest 6 would be underground covering a total distance of 16.6km. East-West Corridor bridge is considered as a path-breaking project for India, as it is the first time that a tunnel has been constructed beneath a flowing river in the country.
The Kolkata Metro transportation has been constructed 30 metres below the river bed, just a few metres away from the famous Howrah Bridge. This project is receiving its fair share of appreciation owing to the fact that not even transportation roads were planned under a river in India, Kolkata metro tunnel- a complete technology marvel will allow the passage of train in every two and a half minutes. “It will connect two main terminals: Howrah and Sealdah- each of which has a footfall, approximately of 10 thousand passengers per day. The tunnel-boring machines have been used for the first time in Eastern India,”- Satish Kumar, MD of Kolkata Metro Rail Corporation Ltd.

More than 10 lakh tonnes of mud have been dug out for the construction of this tunnel using the tunnel boring machines. The construction of the entire 16.6-kilometre stretch is ready whereas the second tunnel of the length 10.8km is still under construction.
The research preparation was done a year before the execution of the plan as tunnel-construction cannot go on for a long time. After this, all the machines and equipment were shifted to the location for implementation of the project. The use of the standard gauge ensures that the tracks have sharp curves as the train will pass through a lot of heritage buildings. The material used in the tunnel gives it immunity to survive quakes in seismic zone 3.
The underwater tunnel is being built at a cost of Rs 60 crore while the total cost of the East-West Metro project is estimated to be around Rs 9,000 crore. Commuters between Howrah and Mahakaran metro stations will be under the river for only about a minute when the metro train will pass through the tunnel at a speed of 80 km per hour. The diameter of each tunnel is 5.55 metre and the thickness of the wall is 275 millimetres. The distance between the two tunnels is 16.1 metre.
There will be walkways in the tunnels for evacuation of passengers in case of emergency


– The underground tunnel will cross the Hooghly river for approximately half a kilometre necessitating a 520m underwater section of the tunnel making the East-West Metro tunnel the first underwater tunnel in India.
– Kolkata Metro Rail Corporation (KMRCL) is executing the project with partial financial support from the Japan Bank for International Cooperation (JICA).
– The underground tunnels are scheduled to be completed in 2020.
– Continuous walkways are being provided for sidewise evacuation during emergencies.