What does the appearance of a signal convey to an approaching train?

The appearance of a signal primarily conveys a signal aspect to an approaching train. Signal aspects are visual indications that inform train operators about the status of the track ahead, such as whether it is safe to proceed, to reduce speed, or to stop. Each aspect, which may involve different colors or arrangements of lights, communicates specific instructions critical for safe train operation.

Understanding signal aspects is essential for maintaining safety protocols on the railway. Proper interpretation of these signals ensures that a train can operate efficiently and within the established speed limits, ultimately minimizing the risk of accidents or misunderstandings regarding track conditions.

The other options, while related to signals, do not accurately encapsulate this function. Signal range, severity, and distance pertain to elements that describe other aspects of railway operations but do not directly relate to the visual indication provided by a signal aspect for train movement.