When should you expect to see a 'Stop Obstruction' banner?

The 'Stop Obstruction' banner is an important signaling device used to indicate that a train must be prepared to stop because its path is obstructed. This type of banner is typically encountered in situations where trains need to operate at Restricted Speed. When operating at Restricted Speed, train crews are required to be more vigilant and slow down sufficiently to be able to stop within half the range of vision, which is crucial when obstructions are possible.

In this context, the option indicating 'Anywhere requiring operation at Restricted Speed' aligns perfectly with the purpose of the 'Stop Obstruction' banner. It serves as a cautionary signal, prompting the engineer to be ready to stop for any unexpected hazards on the track.

The other scenarios listed do not typically warrant a 'Stop Obstruction' banner. For instance, approaching a clear signal indicates that it is safe to proceed without the need for the caution urged by a 'Stop Obstruction' banner. At a station, while caution is required, the typical signals and procedures would not involve this specific banner unless there are specific obstructions or safety protocols in place. Lastly, a stop signal already conveys the necessity to halt, making the 'Stop Obstruction' banner redundant in that scenario. Thus, the correct identification of the