Signals are way-side traffic devices with the purpose to inform operators of approaching trains about the occupancy status of the tracks beyond the signal including information about the path and its speed restriction the train is about to enter. While prototype signals can display a plethora of different aspects to cover all that, the indication shown on the dispatch operator’s desk is normally “clear” or “stop”, ignoring details such as speed restriction and advance signaling – which is left to the system to take care of.
Signals are one-directional and therefore affect and control trains only in its assigned direction. Trains traveling in the opposite direction are not affected.
Signals can also have supporting functionality, such as distant-only signals and triggers,
In CTC signals are placed in control points, which is the “track object” linked into the path a train passes. There is one spot for each direction
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