What is the function of interlocking signals in rail operations?

Interlocking signals play a crucial role in ensuring safe and efficient train operations by controlling the movement of trains through junctions and crossings. Their primary purpose is to prevent conflicting movements of trains, ensuring that only one train can occupy a given block of track at any one time.

When a block limit signal is displayed, it indicates the sections of track that are currently occupied or available for use. It ensures that trains are stopped or allowed to proceed based on the current track conditions, thereby maintaining the safety of train operations. This function directly correlates with the operations of interlocking systems, which coordinate signals and switch operations to manage track usage effectively.

The other choices do not accurately represent the function of interlocking signals. While passenger boarding areas, temporary orders, and changes in operating rules are all important aspects of rail operations, they do not specifically relate to the purpose of interlocking signals, which is focused on the safe movement of trains within controlled areas.