Special Content


Issue no 52, 26 March - 1 April 2022

Kavach: Indian Railways' Armour

Two trains on the same track heading towards each other. From what one can see, a head-on collision is imminent. However, both the locomotives are seen halting when they are nearly 400 metres apart, thus avoiding the mishap.

This feat was recently performed by the Indian Railways when an extensive trial of 'Kavach' was conducted. Union Minister for Railways, Sh. Ashwini Vaishnaw was onboard the locomotive that moved from Gullaguda towards Chitgidda (in Secunderabad Division of South Central Railway). Chairman and CEO of the Railway Board, Sh. V K Tripathi was onboard the locomotive that moved from Chitgidda towards Gallaguda. During the trial, a head-on-collision situation was created. Kavach initiated the automatic braking system and halted the locomotives 380 metres apart.

The focus of the Indian Railways is to increase capacity utilization of existing assets including rolling stock, track infrastructure, traction power and signalling and telecommuni-cations. By running more high-speed trains on the existing infrastructure, passengers and freight carrying capacity as well as revenue and profitability can be increased. In order to ensure safety over high speed and high-density rail networks of Indian Railways, it was felt that automatic prevention systems should be adopted. Indian Railways took up indigenous development of such technology to prevent dangerous train collisions caused due to human errors or limitations and equipment failures by providing an additional layer of enhanced safety in the operations.

What is Kavach?

'Kavach', which literally means 'armour', is an indigenously developed Automatic Train Protection (ATP) system by Research Design and Standards Organisation (RDSO) in collaboration with Indian industry and trials facilitated by South Central Railway. The aim is to achieve the corporate objective of safety in train operations across Indian Railways. It is a state-of-the-art electronic system of Safety Integrity Level (SIL)-4 standards. SIL-4 certified technologies are those with the probability error of 1 in 10,000 years.

ATP is a type of train protection system which continually checks that the speed of a train is compatible with the permitted speed allowed by signalling, including automatic stop at certain signal aspects. If it is not, ATP activates an emergency brake to stop the train.

In addition to preventing collision between two locomotives, Kavach, or the Train Collision Avoidance System (TCAS), is meant to provide protection by preventing trains against Signal Passing at Danger (SPAD), excessive speed, and collisions. It activates the train braking system automatically if the crew either fails to do so as per the speed restrictions, or is not in position to do so.

 During the trial, crossing of the red signal was also tested. The locomotive, however, did not cross the red signal as Kavach necessitated the application of brakes automatically. The automatic whistle sound was loud and clear when the gate signal approached. The crew did not manually touch the sound and braking system during the trial.

The speed restriction of 30 Kmph was also tested when the locomotive was run on a loop line. Kavach automatically reduced the speed to 30 Kmph from 60 Kmph as the locomotive entered the loop line.

Kavach is one of the cheapest SIL-4 certified technologies. It opens avenues of export of this indigenous technology for Railways. The indigenously-developed system costs around Rs. 40-50 lakh for each kilometre, whereas European models cost approximately Rs. 1.5-2 crore for each kilometre.

 Features of Kavach

1. Prevention of Signal Passing at Danger (SPAD)

 2. Continuous update of Movement Authority with a display of signal aspects in Driver Machine Interface (DMI)/Loco Pilot Operation Cum Indication Panel (LPOCIP)

3. Automatic Braking for Prevention of Over Speeding

4. Auto Whistling while approaching Level Crossing Gates

5. Prevention of collision between two locomotives equipped with functional KAVACH

6. SoS Messages during emergency situations

7. Centralised live monitoring of train movements through Network Monitor System. The trackside sub-system of the TCAS consists of Radio-Frequency Identification (RFID) tags fitted on track in the station section and block section for giving Trackside information to the Loco TCAS unit installed in the locomotive. Portions of the track, including berthing tracks, point and block sections, are assigned unique IDs called Track Identification Number (TIN). TIN, along with RFID tags, are used to determine the direction of the train. The system also consists of a Stationary TCAS unit installed at the station with radio tower to communicate with locomotives in the station area. Stationary TCAS is interfaced with station interlocking to acquire real-time dynamic information related with signalling. Route information of all the signals monitored by a specific Stationary TCAS unit is configured on the basis of TCAS Control Table (excluding shunt signals and overlaps). Stationary TCAS unit gets realtime information regarding locations, speed, etc. of various trains in its jurisdiction through Ultra High Frequency (UHF) radio communication.

The advanced accident prevention measures, under which trains will be in constant communication with the protection systems through UHF/LTE communication, will be implemented over Indian Railways in a phased manner.

 Kavach Deployment Strategy

96% of railway traffic is carried on Indian Railway High-Density Network and Highly Used Network routes. To transport this traffic safely, Kavach works are being taken up in a focused manner as per the following priority set by the Railway Board:

First Priority: High-Density Routes and on New Delhi-Mumbai and New Delhi-Howrah sections for 160 Kmph with Automatic Block Signaling and Centralized Traffic Control. These sections have been given first priority since such sections have higher chances of human errors on part of drivers resulting in accidents as trains run closer to each other.

Second Priority: On the Highly Used Networks with Automatic Block Signaling and Centralized Traffic Control.

Third Priority: On other Passenger High-Density Routes with Automatic Block Signaling.

Fourth Priority: All other routes.

The Union Minister for Railways stated that the Kavach is a major step taken by Indian Railways in taking forward Hon'ble Prime Minister of India's initiative of Atmanirbhar Bharat. During the development phase, Kavach was implemented for a length of 264 kilometres covering 25 stations across Wadi-Vikarabad-Sanath Nagar and Vikarabad-Bidar sections over South Central Railway. Later, the system was further extended by additional 936 kilometres, taking the cumulative deployment of Kavach to 1,200 kilometres. As a part of Atmanirbhar Bharat, 2,000 km of the network will be brought under Kavach for safety and capacity augmentation in 2022-23. The system will be further extended to an additional 4,000 to 5,000 Kms from next financial year. Around 34,000 Kms of network will be brought under Kavach. Indian Railways is planning to implement the Kavach protection system over its entire network at the earliest.

Compiled by: Annesha Banerjee & Anuja Bhardwajan

Sources: PIB/Indian Railways/RDSO