The tunnelling work under the Hooghly river, the first such underwater tunnel in India, for the Howrah-Kolkata metro line is completed. 

The 520-metre underwater tunnel will connect the twin cities of Howrah and Kolkata located on either side of the Hooghly. Photo: HT

The 520-metre underwater tunnel will connect the twin cities of Howrah and Kolkata located on either side of the Hooghly. 

New Delhi: The tunnelling work under the Hooghly river, the first such underwater project in the country, to provide metro connectivity between Howrah and Kolkata is completed. 

The underwater tunnel is a crucial link for the railways’ 16.6-km long East-West Metro project in Kolkata.

The 520-metre twin tunnel, one east-bound and the other west-bound, is built 30 metre below the riverbed. 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. Of the 16.6-km route of the East-West Metro project, the tunneling covers 10.6 km, of which 520 metre is under the river.

The underwater tunnel is being built at a cost of Rs60 crore while the total cost of the East-West Metro project is estimated to be around Rs9,000 crore. The tunneling work started in April last year and is completed in the river section. 

The East-West Metro is scheduled to be operational by August 2019. The diameter of each tunnel is 5.55 metre and the thickness of the wall is 275 milimetre. 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 official said, adding it was a challenging task to dig a tunnel under the river.

For the railways, besides the tunnel under the Hooghly river, drilling work is going on for the seven-km-long under- sea route of the Mumbai-Ahmedabad rail corridor to ascertain soil condition for India’s first bullet train path.

Passengers will get the thrill of travelling under the sea at a maximum speed of 350 km/hour, another first in the country, near Thane in the upcoming high-speed train project connecting the two metropolis. 

The construction of first underwater rail tunnel is complete and the most amazing part of it is that it happened ahead of the schedule. The deadline was July 2017.

The companies responsible for digging the country’s first tunnel under the Hooghly River for establishing metro link between Howrah and Kolkata are Afcons Transtonnelstroy and Kolkata Metro Railway Corporation Ltd.

Machine used for digging the underwater tunnel:

Rachna, a giant tunnel-boring machine (TBM), was deployed to dig the underwater tunnel that runs a length of 502 metres under the river.

The machine was brought from Herrenknecht AG plant in Schwanau, Germany.

About the project:

  • The total length of the entire metro project is 16.6 km long, out of which 10.8 km runs under the ground. Of this 10.8 km, 502 metres is under the water
  • The metro rail project connects Howrah to the west and Salt Lake to the east
  • Afcons Transtonnelstroy is responsible for building the project while KMRCL will implement it
  • The stretch of 16.6 km will have 12 stations, six of which will be under the ground, while the remaining six metro stations will be on elevated tracks
  • The final commissioning of the project is scheduled by December 2019, following which it will be operational
  • The total project cost is USD 750 million

Delays faced:

Since the beginning, the project was held up several times mainly due to land allocation, slum relocation and route alignment problems among others.
The project was originally slated to be completed by 2012. It was first postponed to 2015 and finally to December 2019. 


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