Final answer:
When a train whistle becomes inoperative, the train operator must follow railroad safety protocols, such as using alternative signals, reducing speed, and notifying the control center.
Step-by-step explanation:
If the train whistle becomes inoperative enroute, the operator should take specific actions to ensure safety. The situation depicted in the question doesn't clearly state what options are available, but typically, a train operator would need to take precautionary measures and follow established railroad safety protocols.
These protocols can include using alternative signaling methods, reducing speed, increasing vigilance at crossings without active protection, and notifying the appropriate railroad dispatch or control center to inform them of the situation.
As train whistles are critical for warning at crossings and for signaling workers on the tracks, the safety of both passengers and those near the railroad depends on the operator's adherence to safety procedures in the absence of a working whistle.