Types of Indian Railway Train Signals

1. Fixed Signals: These signals are installed permanently. They are normally fixed at the track side.
2. Hand Signals: These signals are used when fixed signals are not working due to certain reasons.
3. Detonating Signals: These signals are used in foggy weathers to indicate the position or locality of a signal to the driver of approaching locomotive. They are placed on the tracks and explode when engine passes over them which make a loud sound which attracts the attention of the driver.
4. Semaphore Signals: They are the older type, of signals widely observed throughout the country. In this, each signal has an assembly with an arm mounted on a pole, where the arm can move through 2 pr 3 different positions at different angles; each position provides a distinct signaling aspect.
5. Colour – Light Signals: These signals are assemblies of lamps that indicate different aspects by means of different colour of lamps that are light. In recent times 5. many semaphore signals have been replaced by colour light signals.
6. Position Light Signals: These signals are the assemblies of lamps where the signals not only indicated by colour aspects but also provides certain combination of the lamps that are lighting up.
7. Disc Signals: There are in the form of a vertical disc with a pattern such as bar painted on it, which rotates about its center to different position to indicate different signal aspects. They are normally mounted the pole but may be close to ground levels.
8. Target Signals: They have a vertical disc or 2 parallel vertical discs which can rotate about its vertical axis so as to present the disc either face on or edge – on to an observer along the track. Normally, a lamp is provided behind the disc or between the parallel discs which is visible only when the discs are oriented edge on. These types of signals are always located at the ground  levels.

Followings are some of the additional types of signals used by the Indian Railways (IR):

1. Two – aspects Lower Quadrant semaphore signaling (2LQ)
2. Modified Lower Quadrant semaphore signaling (MLQ)
3. Multiple Aspect Upper Quadrant semaphore signaling (MAUQ)
4. Two – Aspect Colour – Light signaling (2CL)
5. Three – Aspect Colour – Light signaling (3CL)
6. Four Aspect Colour Light signaling (4CL) or Multiple Aspect Colour – Light signaling (MACL)