What action must the engineer take if the whistle or horn fails en route?

When the whistle or horn fails while en route, the appropriate action for the engineer is to ring the bell continuously and notify the dispatcher. The bell serves as an alternative warning device to alert pedestrians, other trains, and anyone near the tracks of an approaching train. Continuous ringing of the bell helps to maintain safety by providing an audible signal in place of the malfunctioning whistle or horn.

Notifying the dispatcher is also essential, as this communication ensures that other personnel are aware of the situation and can take necessary precautions or provide guidance. This measure supports overall safety protocols and helps to mitigate risks associated with the train's operation under such conditions.

Continuing without warning signals is not safe, as this may lead to hazardous situations where the train could come into contact with people or vehicles unaware of its approach. While reducing speed is a prudent measure, the engineer must take proactive steps to alert others around the train. Proceeding only if it is safe to do so does not account for the immediate need to communicate the train's approach in the absence of a whistle or horn.