After encountering a signal displaying STOP AND PROCEED, how long must a train proceed at restricted speed?

When a train encounters a signal displaying STOP AND PROCEED, it is important for safety that the train operates at restricted speed. Proceeding at restricted speed means the train must be able to stop within half of the range of vision. This ensures that the crew can react appropriately to any changing conditions, obstacles, or other signals that might affect the safe operation of the train.

The requirement to continue at restricted speed "to the next signal" aligns with the purpose of STOP AND PROCEED, allowing the crew to observe the track conditions and be ready to respond appropriately to the next signal's indication. This practice is essential for maintaining safety while giving the crew a clear directive about the distance over which this speed must be maintained.

Proceeding at restricted speed is a fundamental aspect of adhering to the rules concerning signals, allowing for safe train operation even in situations where the signal initially indicates a stop. The other choices, while they may involve the concept of speed and stopping, do not align with the specific requirement following a STOP AND PROCEED indication in terms of safely navigating towards the next signal.