Kolkata Metro is set for a major infrastructure upgrade, with plans to install seven new traction substations along the Blue Line between Dakshineswar and Sahid Khudiram (Birji). The initiative aims to strengthen power supply, improve operational efficiency and enhance passenger comfort on India’s oldest metro corridor. According to reports, the substations will be located at Kalighat, Netaji Bhawan, Maidan, Esplanade, MG Road, Sovabazar–Sutanuti, and between Belgachia and Shyambazar. Once completed, the Blue Line will have a traction substation at every station, mirroring the configuration of the newer Purple Line (Joka–Majerhat) and Orange Line (Kavi Subhas–Beleghata). Additional upgrades are under way, with two more substations planned at Chandni Chowk and Geetanjali (Naktala). These are expected to ease bottlenecks, particularly the congestion of rakes between Esplanade and Central stations. A Kolkata Metro spokesperson said the Chandni Chowk substation would significantly reduce operational delays on this busy stretch. The network’s tunnel and station cooling systems are also being modernised. Earlier, tunnels were kept cool because trains were non-air-conditioned. With the fleet now fully air-conditioned, the Metro is transitioning to a modern Tunnel Ventilation System (TVS) that supports advanced fire and smoke extraction. Previously, mechanical ventilation relied on 110 kW centrifugal fans operating round the clock at fourteen midpoint locations, costing around Rs 210 million per year. Energy-efficient upgrades introduced in 2021–22 halved this power consumption. The ageing fans will now be replaced by axial units capable of operating for two hours even at 250°C, with automatic activation triggered by temperature, smoke or CO? levels. A Japanese subsidiary has been contracted to implement the environmental control upgrades, and engineers have already inspected installations at Jatin Das Park. The project is expected to significantly strengthen fire safety and reduce carbon emissions by 12,300 metric tonnes annually.