When does a train operator sound one long and one short, one long and one short blast of the horn?

The appropriate use of one long and one short, followed by one long and one short blast of the horn is for signaling the train crew that assistance is needed. This specific horn sequence is a universally recognized signal indicating a situation that requires help or intervention, ensuring that other railway staff are aware of an urgent need for assistance.

Understanding this helps train operators communicate effectively in situations where immediate support is necessary, enhancing safety and operational efficiency. Each horn blast communicates a specific message, and using the correct sequence is crucial for standardized responses in the event of an emergency or operational complication.