When moving cars not headed by an engine over a highway crossing, what is required?

The requirement to provide an on-ground warning by a crew member when moving cars not headed by an engine over a highway crossing is essential for safety. This procedure ensures that any approaching vehicles or pedestrians are alerted to the movement of the rolling stock, minimizing the risk of collision. The presence of a crew member signals to both the train crew and the public that someone is actively monitoring the situation, enhancing the overall safety at the crossing. This is especially crucial since unpowered cars could pose a greater hazard than cars coupled to an engine, as they may not be visible until they are very close to the crossing.

Other options reflect misunderstandings of safety protocols. Proceeding without any warning when the crossing gates are down does not account for the comprehensive safety measures designed to protect both rail and vehicular traffic. Stopping only if traffic is approaching fails to consider that even without direct traffic, the potential for accidents remains high if warnings are not given. Lastly, the idea that no restrictions apply at highway crossings overlooks the inherent dangers present when trains and vehicles share these intersections. The strict requirement for ground warnings reinforces the commitment to safety and accident prevention within rail operations.