What does a red signal typically indicate in train operations?

In train operations, a red signal is a critical safety indication. It conveys that the train must come to a complete stop. This is essential for ensuring that trains do not proceed into potentially dangerous situations, such as an occupied track section or when approaching a station where clearance cannot be guaranteed. The requirement to halt is also crucial for maintaining safety protocols, allowing train operators to assess the situation ahead and prevent accidents.

The other choices do not align with the fundamental purpose of a red signal. Proceeding with caution or moving at reduced speed could pose significant risks, as they imply that the train can continue, which contradicts the necessity of stopping completely at a red signal. Similarly, continuing unless directed otherwise would disregard the clear instruction to halt, thereby potentially endangering both train operations and personnel. Thus, the correct understanding of a red signal as a signal to stop completely is vital in train operations for maintaining safety and operational integrity.