Blue Line ACs, ventilation system to undergo 500cr overhaul after 40 years
Times of India | 6 August 2025
Kolkata: Metro Railway has decided to pump Rs 500 crore to revamp the four-decades old air-conditioning and ventilation system between Rabindra Sarobar and Belgachhia stations in the North-South or Blue Line. There are 15 underground stations in this line.
Sources said the tendering for overhauling the environmental control system (ECS) or the air-conditioning system for 15 stations dotting the 16.9 km section from Rabindra Sarobar to Belgachhia that has been floated will also include replacing the AC and ventilation of the twin tunnels. "The work is mainly aimed at ensuring cooler stations and tunnels. It will also improve the fire safety system, making sure there is proper ventilation inside the tunnels when a fire breaks out and passengers need to be evacuated," a source said. He said the air-conditioning and ventilation will be upgraded in accordance with the current ambient temperature, which has risen considerably since metro first started operations around 40 years ago.
The 15 underground Blue Line stations have centralised air-conditioning systems which include water-cooled chillers, towers, coils, and ducts through which cool air is released into the platform, concourse, and mezzanine levels. "These are now considered primitive. They will have to be replaced with modern heating ventilation and air conditioning (HVAC) systems," an official said.
The Blue Line, currently running a 30 km underground and elevated corridor from Dakshineswar to Shaheed Khudiram, was India's first underground metro when its 3.4 km Esplanade-Bhowanipore stretch was launched on Oct 24, 1984. Over the years, it expanded north and southwards across the city's central axis. The southern terminal station at New Garia, Kavi Subhash, was shut down on July 28, when cracks were spotted on the columns supporting the Dakshineswar-bound or Up platform. Truncated operations are run till the second last southern station at Dhalai Bridge, Shaheed Khudiram. Metro Railway announced that the Kavi Subhash station will be rebuilt.
The tender process is likely to end this month, following which the lowest bidder will start the work. Sources said the work will take at least four or five years to complete. "The work will be done while the commercial operations continue uninterrupted. Therefore, work will take time, unlike greenfield projects," a source said.
Surface stations like Dum Dum, Noapara, and those between Mahanayak Uttam Kumar (Tollygunge), Shaheed Khudiram, and Kavi Subhash (New Garia) don't have cooling units.
Officials said the basic design of North-South Metro, done by IIT-Kharagpur, was advanced, but the various equipment used in the metro system need upgradation and replacement due to the passage of time. Keeping this in mind, Metro Railway engaged RITES to conduct a health study.