What does it mean for an interlocking appliance to be SECURED?

When an interlocking appliance is described as being SECURED, it means that it is locked mechanically in a required position. This status ensures that the interlocking apparatus can safely control the movement of trains by preventing unintended changes in the configuration of the switches or signals. By being mechanically locked, it provides a critical safety function, ensuring that track arrangements are stable and preventing accidents caused by erroneous operations.

The other possible meanings do not align with the definition of "secured" in the context of interlocking systems. For instance, if the appliance were operational with no restrictions, it would imply flexibility rather than a secured state. Similarly, being prevented from functioning would suggest a state of inoperability, which is not synonymous with being secured. Actively signaling a block limit refers to a different operational status that does not involve the mechanical lockdown of the appliance. Hence, the precise definition of a secured interlocking appliance focuses on its mechanically locked condition, ensuring safety and stability in railway operations.