When may a train make a reverse movement on any main track?

The correct answer indicates that a train may only make a reverse movement on any main track if it has the authority to occupy that track. This is crucial because train movements on main tracks are strictly regulated to ensure the safety and efficiency of rail operations.

Occupying main tracks without the necessary authority can lead to dangerous situations, including collisions and accidents. Dispatcher authority is essential as it ensures that all train movements, including reverse movements, are coordinated properly with other traffic and that the necessary precautions are in place.

While considerations such as safety and train speed are important, they do not supersede the requirement for proper authorization. This ensures that all trains are accounted for in the dispatching system, and it maintains a controlled environment for rail operations. Without the proper authority, any movement on the main track could disrupt other scheduled train movements or create hazards.