Explained | How does railways' collision prevention system Kavach work?

Three trains derailed and collided with each other in Odisha on Friday evening, killing at least 288 people.

Safety of travel by the Indian Railway has once again come under questions after a horrific derailment caused an accident involving three trains that left at least 288 people dead and over 900 injured.

The accident took place around 7pm on June 2 in Odisha's Balasore. Around 10 to 12 coaches of the Howrah-bound Shalimar-Chennai Coromandel Express got derailed and fell on the adjacent track.

Subsequently, the Bengaluru-Howrah Superfast Express collided with the derailed coaches, sending three to four of its coaches off the track. Some of the derailed coaches of the Coromandel Express skidded off to the loop line and collided with a passing goods train. In all, 17 coaches were smashsed.

Could the implementation of the ‘Kavach’ automatic train protection system have averted the deadliest of train crashes in over two decades? The Indian Railway said that there was no 'Kavach' system on the route, which might have stopped the express trains from the collision.

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 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. At the moment Kavach has been deployed on over 1,098 route km and 65 trains running under the South Central Railway after successful trial runs.

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 said.

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 much will deploying Kavach across Indian Railways cost?

In the first phase Indian Railways will install the new anti-collision system across 2000 rail route networks in 2022-23.

It will later be implemented on 3,000 km of the Delhi-Mumbai and Delhi-Howrah corridors where the tracks and systems are being upgraded to host a top speed of 160 kmph.

The Indian Railways plans to subsequently come out with tenders to deploy Kavach across the entire 68,446 km it operates.

The cost of Project Kavach is around Rs 30-50 lakh per kilometre and private player will be given a timeframe of two-three years to implement the system across different pockets that will be tendered out.

The railways expects to completely shift to the new anti-collision system across all train tracks in India by 2028.

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.

The new Kavach system covers everything from railway stations, signalling systems and even types of trains, while the older ACD or the auxiliary warning system only works on individual trains and locomotives, senior officials from the RDSO said.

The new system is also a lot more accurate in sending signals to trains and is faster as it works on a real-time basis while implementing safety measures as well, officials added.

"The indigenously-developed anti-collision technology is SIL4 (Safety Integrity Level 4)-certified which means there is the probability of a single error in 10,000 years," railways minister Ashwini Vaishnaw had said at the launch of the Kavach.

With inputs from News 18 coverage