In what scenario must trains operate under signal authority?

Trains must operate under signal authority on tracks specified in the timetable because this ensures that operations are conducted safely and efficiently, following the established protocols that govern train movements. The timetable serves as a critical reference for train schedules and track usage, indicating where signals provide the necessary authority for movement.

Operating under signal authority helps prevent conflicts between trains, especially in areas where multiple tracks or services intersect. It maintains a structured flow of train traffic, adhering to the schedules and preventing incidents that could arise from unsanctioned movements.

While peak hours, maintenance periods, and passenger requests might create operational considerations, they do not inherently establish whether trains must operate under signal authority. Adhering to timetable specifications is vital for maintaining overall safety and efficiency on the railway system.