What is KAVACH system?


  • An electronic track management system KAVACH used by the railways has become the focus of investigations after last week’s horrific train crash involving two express trains and a goods train in Odisha’s Balasore district.

What is KAVACH?

  • The KAVACH is an indigenously developed Automatic Train Protection (ATP) system by the Research Design and Standards Organisation (RDSO) in collaboration with the Indian industry.  
  • It is meant to provide protection by preventing trains from passing Red signals and thereby avoid collision.
  • It is a state-of-the-art electronic system with Safety Integrity Level-4 (SIL-4) standards.
  • It is meant to provide protection by preventing trains to pass the signal at Red (which marks danger) and avoid collision.
  • It activates the train’s braking system automatically if the driver fails to control the train as per speed restrictions. In addition, it prevents the collision between two locomotives equipped with functional Kavach systems.
  • The system also relays SoS messages during emergency situations.
  • An added feature is the centralised live monitoring of train movements through the Network Monitor System.
  • ‘Kavach’ is one of the cheapest, SIL-4 certified technologies where the probability of error is 1 in 10,000 years.
Kavach System
What is KAVACH system?

How does Kavach work on Railway Systems?

  • The Traffic collision avoidance system (TCAS), with the help of equipment on board the locomotive and transmission towers at stations connected with Radio Frequency Identification (RFID) tags, helps in two-way communication between the station master and loco-pilot to convey any emergency message.
  • The instrument panel inside the cabin helps the loco-pilot know about the signal in advance without visual sighting, and the permissible speeds to be maintained.
  • If a red signal is jumped and two trains come face to face on the same line, the technology automatically takes over and applies sudden brakes.
  • Additionally, the hooter activates by itself when approaching a level crossing which serves as a big boon to loco-pilots during fog conditions when visibility is low.

What is an interlocking system?

  • Interlocking is an integral part of railway signalling. It refers to a mechanism that controls the movement of trains to ensure trains move safely through a controlled area. The system is an arrangement of signals and points, which may be inter-connected mechanically or electrically or both, which operate so that a train can move from one track or junction to another safely, without coming in the way of another train. 
  • Electronic interlocking (EI) is an advanced signalling, computer-based system that uses electronic components to manage the movement of trains and the configuration of tracks. The EI system is based on software and designed to prevent two trains from running on the same track at the same time. It ensures that a train gets a go-ahead only when the route ahead is clear. The system is an alternative to the conventional Relay Interlocking system. 

The EI signal system comprises three crucial elements: 

  • Signal: Based on the status of the track ahead, signals are used to tell a train to stop (red light), proceed (green), or exercise caution (yellow).
  • Point: A train can change its track using a point. These are movable sections of a track which guide the wheels towards either the straight or diverging track. Points are operated using switches to lead trains in the desired direction. For instance, if a train has to change lines, the switch point is activated ahead of time and the point is locked. A point machine is a device used for locking point switches and plays an important role in the safe running of trains.
  • Track circuit: These are electrical circuits on tracks to detect the presence of a vehicle or a train on a section of track. Track circuits help to verify whether a particular route is clear or occupied and if it is safe for a train to proceed.

How does the system work? 

  • Two information points form the basis of the EI signal system — a signal to pass is given based first on which direction the track is set, and second on whether the divergent track is free of obstruction.
  • A moving train first gets a signal if it has to move straight or switch to a new track.
  • The EI system then directs a train to an empty track at the point where two tracks meet. And circuits prevent another train from running on that block.
  • All activities in the signalling system are recorded in a microprocessor-based system called a data logger.
  • It acts like the black box of an aircraft and can store and process signal data to generate reports.
  • The affected stretch where the accident took place on Friday (June 2) was also equipped with an EI system.




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