iCBTC : Helping towards unmanned train operations

A CBTC system is a continuous, automatic train control (ATC) system that uses high-resolution train location determination independent of track circuits; continuous, high-capacity, bidirectional train-to-wayside data communications; and train borne and wayside processors capable of implementing automatic train protection (ATP) duties.

iCBTC : Helping towards unmanned train operations
iCBTC : Helping towards unmanned train operations

NEW DELHI (Metro Rail News): Communications-based train control (CBTC) is a railway signalling system that utilizes telecommunications between train and track equipment to regulate traffic and control infrastructure. The exact position of a train is known more precisely with CBTC systems than with traditional signalling systems. This results in a more efficient and safe way of managing railway traffic. Metros (and other train systems) can increase capacity while maintaining or even enhancing safety.

A CBTC system is a continuous, automatic train control (ATC) system that uses high-resolution train location determination independent of track circuits; continuous, high-capacity, bidirectional train-to-wayside data communications; and train borne and wayside processors capable of implementing automatic train protection (ATP) duties, as well as optional automatic train operation (ATO) and automatic train supervision (ATS) services, as defined in the IEEE 1474 standard. CBTC can be classified based on operational requirements:

  • Only ATP functions without ATO or ATS. 
  • ATP and partial ATO and / or ATS functions.
  • CBTC can be only train control system or may be used in conjunction with other auxiliary wayside systems. 

Trains in modern CBTC systems constantly compute and broadcast their status to wayside devices spread along the line via radio. This status comprises, among other things, the exact position, speed, travel direction, and braking distance. This data enables for the computation of the area that the train could potentially occupy on the track. It also allows the wayside equipment to identify the spots on the line that must never be passed by other trains on the same track. These points are conveyed to the trains in order for them to automatically and continually alter their speed while meeting safety and comfort (jerk) standards. As a result, the trains continuously receive distance information from the preceding train and can change their safety distance accordingly.

CBTC : Key Features

  • Continuous Automatic Train Protection (ATP), Automatic Train Operation (ATO), and Automatic Train Supervision (ATS) are implemented with wayside and train-borne processors by processing train status and control data.
  • The maximum capacity per track design is obtained through CBTC signalling. The system can support maximum number of trains. There are no trackside signals or track circuits. Greater precision in determining train location – independent of track circuits. Continuous data exchange between the train and the wayside.
  • Unlike traditional signalling systems, where block length is fixed, CBTC employs the Moving Block concept, in which block length is continuously modified based on the speed of the preceding train.

Processes of Operation 

CBTC works in following stages: 

  • High precision train location detection without track circuits, by train-borne system.
  • Transmission of train location & other train status data to wayside controller/equipment.
  • Wayside controller generates limit of Movement Authority (MA). 
  • Transmission of MA to train-borne system. 
  • Determination and enforcement of ATP profile by train-borne equipment
  • Implementation of MA by train-borne system.
  • Communication of commands from wayside to external interlocking and status from external interlocking to wayside. 
  • Communicating data from one wayside controller to other wayside controller.
  • Communication between multiple sets of train-borne equipment within a train. 

Benefits of CBTC 

  1. CBTC makes effective use of infrastructure in following ways: 
  • Allows trains at closer headways. 
  • Greater precision and control of trains is possible. 
  • Provides continuous safe train separation & over speed protection. 
  • Utilizes the track in the most efficient manner while ensuring safety. 

2. CBTC requires less maintenance cost due to: 

  • Driverless system (or upgradable to driverless) to reduce operating costs;
  •  Less wayside equipment 
  • Improved reliability
  • Real time diagnostic data 


I-CBTC : An Introduction 

With a total route length of 68,103 kilometres as of 31 March 2022, India runs the world’s fourth largest national railway system. The Indian Railways, the country’s principal transport system, operates the largest rail network in Asia and the world’s second largest under one control. India, known for its complex and intricate railway network, may soon see a significant transition away from conventional railway signalling systems, as Bharat Electronics Ltd (BEL) has signed an agreement with Delhi Metro Rail Corporation to jointly develop an indigenous communication-based train control system (i-CBTC).

Salient Features

  • i-CBTC, which is being developed in India for the first time, shall enable unmanned metro and train operations. It is a significant step forward in metro and rail automation, and it will support the Government of India’s ‘Atmanirbhar Bharat’ mission. The project is being carried out under the auspices of the Government of India’s Ministry of Housing and Urban Affairs (MoHUA). The MoU seeks to benefit on BEL and DMRC’s complementary strengths and skills.
  • Traditional railway signalling relies on colour light signals and train detection via track circuits and axle counters. Although this technology is suitable for train detection and control, it is still unable to fully utilise section capacity. The indigenous communication-based train control system (iCBTC) enters the scene.
  • For traffic management and infrastructure control, the current communication-based system utilizes telecommunications between the train and track equipment. It facilitates tracking the precise location of a train, which is superior compared to conventional signalling methods. It helps in a more effective and safe railway traffic management. This helps in  Metros (and other train systems) enhance headways while preserving or even improving safety.
  • With the integration of cutting-edge innovation, the i-CBTC is the preferred choice of mass transit railway operators globally today, with over a hundred systems already in operation. In India, the technology is also being used in metro systems. With a rise in population throughout major cities/towns, the requirement for mass transit and signalling systems must evolve and adapt to safely meet this increase in demand and traffic capacity. As a result, i-CBTC is being widely embraced for its characteristic of moving blocks, which allows for high frequency of system operation and guarantees efficient use of Metro infrastructure while also guaranteeing safe operations.


i-CBTC is a modern communication-based technology that employs radio communication to convey accurate and fast train control information. The system will enable unmanned metro and train operations, representing a significant advancement in the field of automation. It is a significant step toward the development of an indigenously built signalling system in India abd a significant step toward achieving self-sufficiency in Metro Signaling and Train Control Systems. This will facilitate and encourage innovation, improve local talent, lower Metro deployment costs, and contribute to the evolution of expertise inside the country in the field of train control signalling systems.

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