Bengal Train Accident: What is Kavach, India's anti-collision shield? How it could have prevented such tragic crash

A tragedy on the Guwahati-Delhi route in West Bengal has cast a spotlight on Kavach, an indigenous anti-collision system being implemented across India's vast railway network. The accident, where a goods train rammed into the Sealdah-bound Kanchanjunga Express, claimed 15 lives and injured over 30. While the cause of the crash is under investigation, the absence of Kavach on the route has sparked critical discussions on the internet about prioritizing railway safety.

What is Kavach?

Kavach, meaning "armor" in Hindi, is an Automatic Train Protection (ATP) system designed and developed in India. It functions as an electronic shield, constantly monitoring the distance between trains and automatically applying brakes to prevent collisions in case of signal breaches or driver negligence.

The system works by integrating trackside sensors with the onboard locomotive unit. Trackside transponders transmit data on signal aspects and line occupation to the locomotive. The onboard unit continuously calculates safe braking distances based on speed and pre-defined parameters. If a situation arises where a collision is imminent, Kavach automatically applies brakes, irrespective of the driver's actions.

How does it function?

Kavach automatically controls train speed by applying brakes if the driver doesn't do so in time.

RFID (Radio Frequency Identification) tags are placed on tracks, station yards, and signals to identify tracks and locate the train and its direction. When activated, Kavach stops all trains within 5 km to allow a train on an adjacent track to pass safely.

The On Board Display of Signal Aspect (OBDSA) helps loco pilots see signals even in low visibility due to bad weather. Normally, they have to look out the window to spot the signals.

The safety system alerts the loco pilot when approaching a red signal and automatically applies brakes if needed to prevent passing the signal.

Railway Minister Ashwini Vaishnaw had said in 2022 that he had personally tested the safety system.

"Rear-end collision testing is successful. Kavach automatically stopped the locomotive before 380 m of other locomotive at the front," he said in a post on X.

The system also sends SOS messages during emergencies.

Kavach is currently installed on over 1,500 km of tracks. The government planned to extend it to 2,000 km of rail network during 2022-23, to cover around 34,000 km. The entire Indian Railway system spans over 1 lakh kilometers.