The construction of the first underwater metro tunnel in the country cutting deep inside the bed of the Hooghly river. By the end of July, two tunnels running parallel will connect the twin cities of Howrah and Kolkata located on either side of the Hooghly. The construction is a first in India, the two 520-metre structures are part of a 10.8 km underground stretch and are crucial to the East West Metro project

About the Tunnel

• The tunnels are being dug at a depth of 30 metres below the earth’s surface and 13 metres below the riverbed.
• The twin tunnels, about 520 metres long, are crucial to the much-awaited ₹ 8,900 core East West Metro project that will connect Salt Lake Sector V in the eastern part of Kolkata to the Howrah Maidan across the river.
• The diameter of the two tunnels running across the river is 5.5 metres and the distance between the two tunnels will vary at different places.

Concern over heritage site

• Three heritage buildings in Kolkata and the existing rules, construction and mining operations are prohibited within 100 meters of protected monuments.
• over the concern of Archaeological Survey of India, an expert committee from the Indian Institute of Technology found no adverse affect on the protected monuments.

Source : The Hindu

GS III : Infrastructure: Energy, Ports, Roads, Airports, Railways etc