Major Capacity Upgrade Planned for Kolkata Metro Blue Line at ₹671.7 Crore Outlay.

The Centre has approved rail infrastructure projects worth ₹895.3 crore aimed at upgrading the North-South metro corridor and rebuilding a key ageing railway bridge, marking a significant boost for the state’s transport network.

Of the total allocation, ₹671.7 crore has been earmarked for the modernisation of the Blue Line of the Kolkata Metro Blue Line, while ₹223.5 crore will be used to reconstruct the railway bridge over the Damodar river under the South Eastern Railway network.

Officials said the Blue Line upgrade is expected to dramatically improve commuter experience, particularly by reducing waiting times. A Metro Railway official noted that once the project is completed, the corridor will be capable of operating at a 2.5-minute headway, significantly increasing train frequency from current levels. The line currently serves around six lakh passengers daily.

The 41-year-old corridor, which runs through Kolkata, was originally designed for trains at five-minute intervals, but rising demand has pushed the system beyond its intended capacity. Officials said higher frequency operations are now essential to ease peak-hour congestion.

To enable faster and more frequent services, the upgrade will involve a comprehensive overhaul of infrastructure, including installation of traction substations at each station, replacement of the existing steel third rail with aluminium, and a transition from the current Train Protection and Warning System (TPWS) to the more advanced Communication-Based Train Control (CBTC) system.

The power system revamp includes seven new traction substations worth ₹291 crore, upgrades to auxiliary and traction substations, and a shift in power supply from 11 kV to 33 kV across key sections. Strengthening works will also be carried out between Esplanade and New Garia, along with improvements on elevated stretches between Netaji and Kavi Subhas stations.

The CBTC system, which allows trains to operate as “moving blocks” by continuously communicating with track signals, is expected to enable even shorter headways of around 90 seconds in the future. Current operations are limited by older signalling systems and a maximum speed of 55 kmph, except on select stretches such as Noapara to Dakshineswar where trains can run up to 80 kmph.

The Blue Line also faced operational disruption in July 2025, when the Kavi Subhas terminal station was shut after cracks were detected in one of its platforms. Since then, services have been curtailed up to Shahid Khudiram, the second-last southern station, and reconstruction work on the terminal is expected to begin shortly.

Officials added that the existing power infrastructure is nearing saturation and increasingly difficult to maintain due to spare parts shortages. The planned upgrades are expected to improve reliability, reduce disruptions, and support long-term capacity expansion on one of the city’s busiest metro corridors.