Kanchanjungha Express train accident: How does railways' collision prevention system 'Kavach' work?

West Bengal train accident: This incident has brought forward the issue of the railways' automatic train protection system, "Kavach" being missing.

A devastating train accident claimed the lives of at least 15 passengers and left 60 others injured in Darjeeling's Darjeeling district on June 17 morning as the Sealdah-bound Kanchanjunga Express was stationary when a goods train collided with its rear coaches, causing a massive derailment, authorities revealed.

Both local and central agencies, alongside residents, were working tirelessly to rescue any trapped passengers. Tragically, among the deceased were the pilot and co-pilot of the goods train and the guard of the passenger train, according to senior railway officials.

This incident has brought forward the issue of the railways' automatic train protection system, "Kavach" being missing. Moreover, news agency PTI reported that the initial investigation has revealed that the automatic signalling system between Ranipatra Railway Station and Chattar Hat Junction in West Bengal, where the accident took place, was defective since 5.50 in the morning.

Could the implementation of the ‘Kavach’ automatic train protection system have averted the tragedy? Let's delve into it.

What is Kavach?

The railways has been developing its own automatic protection system since 2012 as Train Collision Avoidance System (TCAS), which got rechristened Kavach or 'armour'.

Kavach was developed by the Research Design and Standards Organisation (RDSO) under Indian Railway (IR) in collaboration with Medha Servo Drives Pvt Ltd, HBL Power Systems Ltd and Kernex Microsystems.

Since 2016, the railways has been carrying out field tests for Kavach on passenger trains.

The Indian Railways had earlier said that it has plans to install Kavach across 2,000 rail route networks in 2022-23 and over 4,000-5,000 rail route networks every subsequent year.

As part of the new system, railway tracks, signalling systems on railway tracks and the engines of trains are installed with radio frequency devices that continuously send signals back and forth on a real-time basis to indicate that the track on which the train is operating has no obstacles.

The devices also continuously relay the signals ahead to the locomotive, making it useful for loco pilots in low visibility. Kavach also controls the speed of the train by an automatic application of brakes in case the loco pilot fails to do so. It helps the loco pilot in running the train during inclement weather conditions such as dense fog.

The system is certified for Safety Integrity Level-4 by reputed international safety assessors (ISAs). Similar safety systems are followed in other countries. Further operational improvement of Kavach is in the works, including change over from Ultra High Frequency (UHF) communication to LTE-4G communication.

At the moment, Kavach uses ultra-high frequency radio waves but the Indian Railways is working to make it compatible with 4G Long Term Evolution (LTE) technology and develop the product for global markets.

Would Kavach be used to avert a similar accident in the future?

Kavach uses a network of devices mounted on trains to avoid collisions. The devices use radio technology and GPS to precisely assess the location of two trains and automatically initiate the braking system if they are at risk of colliding.

"The Kavach system if implemented would have applied the breaks on the Bengaluru-Howrah Superfast Express as the system would have picked up the signal of the path in front being blocked," a senior government official had said earlier.

He added that while it is difficult to say for sure that now collision would have taken place, the impact of collision would be significantly lower with the use of the Kavach system.

"At the moment it would be difficult to say for certain that the Kavach system would have prevented the complete collision, that would depend on the distance and speed of the trains and how quickly the system would have time to respond," the official said.

Another former railway ministry official said that if the derailment and collision were separated by more than 5-10 minutes the Kavach system would have definitely prevented the accident.

But how does the new automatic train control work?

As part of the system, obstacles that are up to 10 km ahead will be detected by devices installed on railway tracks.

These devices then send signals to the device installed in trains to reduce speed to up to 30 km per hour, after which the driver of the train can bring the train to a halt.

Railway tracks will also be fitted with pressure sensors that can detect weights of above 500 kg and send signals to a train’s engine to automatically apply brakes.

Trains will also start reducing speed on their own when the digital system notices any manual error.

The signals sent between the devices on a train track and train work on unique radio frequencies and are transmitted directly between the two devices rather than through a central server.

How is the new system different from the older system used by IR?

The Indian Railways has since 2002 been using an anti-collision device (ACD) developed by Konkan Railways, which was dubbed ‘Raksha Kavach’.

The ACD system was invented by the former head of Konkan Railways Rajaram Bojji.

While the older system is still in use in most trains operated by Indian Railways at the moment, the new system will be introduced across all trains in the next five years.

Indian Railways, managing the fourth largest railway system globally, has over 68,000 kilometers of routes. The total expenditure on the development of Kavach stands at Rs 16.88 crore.

Note: This story has been repurposed from earlier Moneycontrol article to reflect updated news on Bengal train accident.