The Centre has sanctioned Rs 6,717.2 million (mn) for an upgrade of electrical infrastructure on the north-south corridor of Kolkata Metro Railway. The allocation aims to increase train frequency on the Blue Line, which currently operates with a peak-hour headway of five minutes and is planned to be reduced to two-and-a-half minutes by 2030. A Press Information Bureau release dated May 2 set out the sanctioned works and funding split.

Of the total, Rs 2,910.6 mn will be used to install seven additional traction substations and Rs 3,806.6 mn will replace transformers, rectifiers, high-speed circuit breakers and the network of cables. Engineers said that each station requires a traction substation for shorter intervals and that modern traction substations can now handle 33KV alternating current directly. The Blue Line was built in the 1980s and retains five receiving substations that step down high-voltage power before it reaches older traction equipment.

The corridor has 26 stations and 13 traction substations, and the sanctioned work will add eight more so that most stations have dedicated traction supply, with an extra substation planned between Dum Dum and Belgachia because of the longer distance. Two new traction substations at Chandni Chowk and Gitanjali are nearing completion and are expected to be operational by the end of July. The seven additional substations will be located at Kalighat, Netaji Bhawan, Maidan, Esplanade, MG Road, Sovabazar and between Belgachia and Dum Dum.

Upgrades are intended to reduce energy losses and enable faster train acceleration by replacing the steel third rail with an aluminium one, which offers improved electrical conductivity and lower voltage drop. The works are being implemented in phases; most of the underground section has been upgraded while the elevated stretch between Tollygunge and Kavi Subhas remains to be completed. Officials said the investment will save energy and operating costs and support the planned increase in service frequency.