To expand the metro rail network in the city, Kolkata is set to get three underground tunnels. The tunnelling work is being carried out taking precautions to protect the century-old building of the Calcutta Municipality. According to global norms, if there is a distance of two and a half km or more between the two underground metro stations, a station must be built in the middle.
In the East-West Metro project of Kolkata, the distance between Sealdah and the Esplanade is more than two and a half km, for which a station at the Subodh Mallick Square had to be built. But due to a lack of land, a giant shaft or cavity like a well is being constructed there.
The tunnels are being constructed around 13 meters below the ground. Two of these are ventilation tunnels, with an emergency tunnel below to facilitate a safe exit for the passengers. The entry point of the tunnel starts at 13 meters below the ground and ending point for ventilation shaft will be at least 22 meters below the ground. The construction work is being done under constant monitoring of the ITD engineers. Project engineer, Dinesh Dani, informed that there are many aquifers in this place from where the water is drawn and the century-old Calcutta Municipality building is not far from the spot where the tunnels are being dug. The vibration while digging the tunnel could also pose a problem for the floor of the Municipality as well as other nearby old buildings. Hence the work is being executed slowly and cautiously.