In an emergency, what should a train operator do to reverse the motors of a moving train when the controller is in an ON position?

In an emergency situation, it is crucial for a train operator to prioritize safety and ensure the smooth operation of the train's controls. Placing the brake handle in emergency and moving the controller to OFF is the correct course of action because it effectively cuts power to the motors, allowing the operator to safely stop the train.

When the controller is in the ON position while the train is moving, attempting to reverse the motors without properly disengaging the power can cause mechanical failure or safety hazards. By transitioning to the emergency brake, the operator can bring the train to a halt, ensuring that reversing does not occur while the train is still in motion, which could lead to dangerous situations.

Other methods, such as moving the controller back and forth, could result in mechanical issues or failure to safely manage train operations. Gradually reducing speed before reversing may not adequately address the urgency of an emergency situation. Furthermore, calling dispatch for instructions may delay critical responses needed to protect the train's safety and crew. Recognizing the immediate need for decisive action in emergencies is essential, which makes this particular answer the best choice.