India's first underwater metro tunnel in Kolkata to be ready in 2023

The construction of India's first underwater tunnel in Kolkata under the Hooghly river that will connect Howrah and Kolkata through metro will be made fully functional by 2023. The tunnel corridor is built 33 metres below the riverbed. "Important passage work has...been done...if a technical problem arises...passengers can be taken out through the special passage," the site supervisor said.