Kavach - Indian Railways

KAVACH () is an Indian Automatic Train Protection (ATP) system indigenously developed by Research Designs & Standards Organisation (RDSO) in collaboration with ''Medha Servo Drives, Kernex Microsystems'' and ''HBL Power Systems''. Initially it was known by the name Train Collision Avoidance System (TCAS). Kavach was adopted by Ministry of Railways as the ''National ATP System'' in July 2020.

Development of Kavach began in the year 2011 as an open architecture system. In 2014, field trials commenced. First field trial experiments on passenger trains was done in February 2016. Subsequently, Kavach received Safety Integrity Level (SIL-4) certification in the year 2019. It is being promoted as one of the cheapest ATP systems available worldwide.

The Union budget of India for the FY 2022-23 allocated funds for the rapid implementation of Kavach across 2,000 km of track, as well as sanctioning its implementation along 34,000 km track of the Golden Quadrilateral rail route, which is to be implemented by 2027-2028.

Overview

Kavach incorporates several key characteristics of the European Train Control System (ETCS) as well as the Indian Anti-Collision Device (ACD); however, ETCS is wider in its scope, since Kavach is not intended to function as a replacement for traditional Lineside signals. While ETCS requires a centralised trackside infrastructure, Kavach is distributed, permitting piece-meal deployments. Kavach is also not intended to have interoperability with other country's systems, unlike ETCS' rigorous cross-border interoperability requirements. These aspects make it cheaper than ETCS.

To use Kavach, each train must be either built with compatible apparatus or to undergo a retrofit of such apparatus. The system consists of few core elements, out of which computer and UHF/GSM radio infrastructure (which consists of radio modems and antennas) are fitted, both at stations and onboard the locomotives; remaining are the radio-frequency identification (RFID) tags, that are placed between the running rails; and onboard the locomotives, there are RFID readers to read those RFID tags placed on the tracks along with a Brake Interface Unit (BIU) to provide Kavach, the interface to control the locomotive's braking system.

Kavach uses many data inputs to ascertain the location and direction of the train. The timing data is confirmed by a GPS satellite link, while the location and direction are measured by an odometer that resets itself whenever the train passes over an RFID tag. Loco Pilots are provided with information through a DMI screen; an event recorder is present to retain a record of all interactions. Specific data exchanged includes speed, direction, location, and identifiers (individual to train and tracks). Some of the track-fitted RFID tags are used for additional purposes, such as to communicate an upcoming signal, level crossing, or the train's entry and exit from a Kavach-covered area.

All messaging between trains and the trackside infrastructure is handled through radio communication. The radio towers used by the Kavach for communication are installed alongside the tracks, aligned with the lineside signalling equipment and railway stations, and are deployed at a regular interval of 1–5 km, depending on the overall terrain. Kavach communicate with relevant signalling control stations, being interfaced with both Electronic interlocking (EI) and Route Relay Interlocking (RRI) systems, functioning in both absolute and automatic block signaling sections to retrieve information on signal aspects, permitted speeds, movement authority, and any restrictions; these criteria are continuously and automatically checked against each train's reported criteria and presented to the Loco Pilot on the DMI screen. The GSM-R radio link is also used to send data to the Network Monitoring System (NMS) to log all train movements, inputs, and fault messages; where appropriate fault teams are automatically contacted to address issues that arise in real time.

The initial implementation of the system harnesses ultra high frequency (UHF) radio frequencies, while the LTE-R based version of Kavach (Version 4.0) will soon be rolled out. Also, work is underway to integrate Kavach with Traffic Management System (TMS), Electronic Interlocking System (EIS).

Functions

Primarily, Kavach works on the principle of continuous supervision of the movement authority and is designed to maintain train speed within the specified limits and can automatically apply brakes to slow down or to bring the train to a complete standstill, in case the Loco Pilots violates the speed restrictions or fails to act in time to prevent Signal Passed At Danger (SPAD); thereby reducing the risks of collision in block sections and on running lines at stations. It displays upcoming signal aspects in the Loco Pilot's cab on the DMI screen; this feature aids in the operation of high-speed trains and assists Loco Pilots during low visibility weather conditions.

Additionally, Kavach offers few Non-Signalling based Non-SIL features such as; providing protection from head-on, rear-end, and side collisions by estimating the length of the track that the train is occupying in a block section and identifying the track that the train is on. It can detect and stop the train in case of a rollback. It automatically blows horn when approaching a Level crossing and manual SOS function which would trigger emergency brakes of all nearby trains.

Development

Origins

During the early twenty-first century, Indian Railways became increasingly interested in deploying automatic train protection (ATP) upon its existing mixed-traffic routes. An extensive evaluation of internationally available systems, such as the European Train Control System (ETCS), was conducted; it was ultimately concluded that there was no existing off the shelf ATP system that fulfilled its requirements. These requirements included the prevention of instances of Signal Passed At Danger (SPAD), collision prevention, in-cab signalling, automatic whistling at level crossings, intelligent real-time health monitoring, and to facilitate substantial speed and capacity increases for both freight and passenger operations. A further key target to be pursued in part via the addition of ATP is the Indian Railways’ ambition to achieve a zero accident rate.

Instead of procuring and installing an existing system, a project to domestically develop a suitable ATP system was pursued by Indian Railways instead. During 2011, work on what would become Kavach commenced; this project was originally titled as the ''Train Collision Avoidance System (TCAS)''. An early Proof of concept was produced in 2012 while a development order for the design and manufacture of the system was issued during the following year. It is an Open architecture system, as there was an explicit requirement for it to be interoperable between multiple vendors unlike in the case of Anti-Collision Device (ACD).

During 2014, the deployment of an initial trial system along a 265 km section of line commenced, upon with the first real world evaluations of Kavach were performed.

Validation

Between 2015 and 2017, field trials of the system were carried out. Data and experiences gathered from these trials were used to refine the specification, which was formalised in March 2017. Final approval of the system was issued in 2019, permitting the training of railway employees on Kavach ahead of the formal rollout and commencement of operations. Kavach has been subjected to tests performed by an Italy based Independent Safety Assessor (ISA) ''ITALCERTIFER S.p.A.'' to validate its performance. The Stationary Kavach achieved Mean Time Between Failures (MTBF) of 60,000 hours, MTBF of Loco Kavach is 40,000 hours while the RFID Reader, Radio modems and GPS/GSM antennas have recorded MTBF of 100,000 hours; reportedly achieved an overall availability of 99.9% during testing. Accordingly, it has been certified with Safety Integrity Level (SIL)-4 for compliance with the CENELEC/ EN standards as per ''EN 50126:1999'' (covering specification and demonstration of RAMS

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