What generally indicates that a train should stop?

A stop signal is a clear and definitive indication that the train must come to a complete halt. These signals are an essential part of railway operations, providing critical information that ensures the safety of both passengers and crew. When a stop signal is displayed, it usually means that there is a hazard ahead, such as another train on the same track, maintenance work, or any other situation that requires the train to stop to prevent accidents.

In contrast, a proceed with caution signal indicates that a train may continue but with heightened awareness of potential hazards. Non-illuminated signs may not convey any specific directive, and a time control signal pertains to the scheduling of train departures rather than an immediate requirement to stop. Thus, the presence of a stop signal is the most authoritative instruction for a train operator to act promptly and bring the train to a stop.