Which system is used for individual train detection?

The use of track circuits for individual train detection is essential in ensuring the safe operation of railway systems. Track circuits consist of electrical devices that detect the presence of a train on a specific section of track by detecting a change in voltage when the wheels of the train create a circuit. This method allows for real-time monitoring of track occupancy, enabling operators to determine whether a segment is clear or occupied.

When a train passes over a track circuit, it completes the electrical circuit, signaling to the control systems that a train is present. This information is crucial for preventing collisions and managing train movements efficiently by maintaining proper spacing between trains. Therefore, track circuits play a vital role in overall train safety and operational integrity. The other options either pertain to different aspects of railway operations or do not directly serve the function of detecting individual trains.