Which whistle signal indicates "One long and two short blasts"?

The signal indicating "One long and two short blasts" is indeed used to communicate that a train is approaching. This specific whistle signal serves as a cautionary alert to indicate to passengers and personnel in the vicinity that the train is on its way, ensuring that they are aware and can take appropriate safety measures.

In rail operations, clear and consistent communication through whistle signals is crucial for safety and efficiency. This particular configuration of long and short blasts is standardized within the guidelines of rail signaling, facilitating immediate recognition by those who are familiar with these signals.

Other signals, such as those indicating preparation to move, an all-clear status, or a change of direction, utilize different combinations of blasts that serve different purposes and contexts in railway operations. Thus, the unique pattern of one long followed by two short blasts unequivocally conveys the message of an approaching train, highlighting its importance in managing rail safety.