Kolkata: The sheer expertise and professionalism with which the tunnelling work for the East-West (E-W) Metro project in Kolkata has been executed forms a major part of the project that will be aired on the National Geographical Channel on Sunday.



"The execution of the project has followed extreme engineering expertise and technology. The model that has been followed is being practised as a standard in similar kinds of projects all over India. National Geographic Channel will showcase the work that we have done on behalf of the executing agency of the E-W Metro — the Kolkata Metro Railway Corporation Limited (KMRCL) in an hour-long show on Sunday," said Satya Narayan Kunwar, project manager Afcons Infrastructures Limited, the construction company that has dug the twin tunnels from Howrah Maidan till Mahakaran.

The Afcons have done tunnelling for three of the six underground stations in the alignment of the E-W Metro project that includes Howrah Maidan, Howrah and Mahakaran. Four ventilation shafts in each of these stations have also been done by Afcons. "We have been working for Metro projects in Chennai and Ahmedabad. But the evacuation plan was not required in both of these places. It was only in Kolkata where we have had to execute an evacuation plan. It was really challenging but we did a commendable job," Kunwar said. The lighting arrangements in the stations are energy efficient and the intensity will be controlled as per requirement. The faucets of water in the Metro stations have been designed in such a manner that the volume of water ejection from the taps will be less but the coverage will be maximum. Underground tunnelling work in close proximity of dangerous and dilapidated buildings was another major challenge with 165 buildings being located in the influence zone. 20 of these buildings were vulnerable and 18 were highly vulnerable, three were heritage structures while two were ASI monuments. "We adopted several measures to minimize the impact of the tunnelling work in these structures," a senior Afcons official added.

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 train will pass through the tunnel at a speed of 80 km per hour. Of the 16.6-km route of the E-W Metro project stretching from Salt Lake Sector V to Howrah Maidan, the tunnelling covers 10.6 km of which 520 metre is under the river. Such under-the-river tunnelling is the first of its kind in India. "The tunnelling under the river was scheduled to be finished in 120 days' time. But the work was completed in half the time," Kunwar added.