First underwater rail tunnel in India
The tunnelling work under the Hooghly river, the first such under-river project in the country, to provide Metro connectivity between Howrah and...
The tunnelling work under the Hooghly river, the first such under-river project in the country, to provide Metro connectivity between Howrah and Kolkata is slated to be completed next week, much ahead of its deadline in July. This is the first such project in the country. Building a tunnel under the river had never taken place elsewhere in India. Further being built under Ganga, it has an emotional value as well.
The tunnel is a crucial link for the 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 under the river. The under-river tunnel is being built at an expense of Rs 60 crore while the total cost of the East-West Metro project is estimated at around Rs 9,000 crore. The East-West Metro is scheduled to be operational by August 2019. The internal diameter of each tunnel is 5.55 meters and the thickness of the wall is 275 mm.
The distance between the two tunnels is 16.1 meters. The 502 meter-long tunnel under the Hooghly River is dug jointly by Afcons Transtonnelstroy and Kolkata Metro Railway Corporation Ltd. The entire stretch will have a total of 12 stations, of which 6 will be underground. Two parallel tunnels will connect the cities of Howrah and Kolkata, located on either side of the river Hooghly.
The 520 metre tunnels under the river will connect Salt Lake Sector V in Kolkata to the Howrah Maidan across the river. The tunnels are being dug at a depth of 30 metres below the earth’s surface and 13 metres below the riverbed. There will be eight stations, two of which are on underground. All the four stations in Phase II (Sealdah-Howrah) will be underground. The costs had gone up from Rs 250 crore in 2011-12 under the UPA rule to Rs 328.81 crore in 2015-16 and now Rs 1,937 crore.