Train engineers blow the train whistle when they...

Train engineers blow the train whistle primarily to signal their presence and ensure safety, particularly in emergency situations. The whistle serves as an audible warning to alert nearby pedestrians and drivers of the train’s approach, which is crucial in preventing accidents. In emergencies, such as when there is an obstruction on the tracks or a need for caution, the whistle's sound can warn people in the vicinity to stay clear and allow for safer navigation.

While blowing the whistle can also occur in other contexts—like signaling at train stations or when crossing certain structures—its fundamental purpose is rooted in maintaining safety, especially during emergencies. This proactive measure helps to manage risks associated with train operations, emphasizing the critical role of communication in transportation safety.