What actions are prohibited for passengers while the train is in motion?

Occupying the vestibule is prohibited for passengers while the train is in motion due to safety and operational reasons. The vestibule area serves as a transition space between train cars and is critical during emergencies. Keeping this area clear enhances passenger safety, allowing quick access for emergency personnel if necessary and preventing any obstruction that could impede evacuation or impact the train's operation.

In contrast, standing in the aisle may be allowed under certain conditions, especially if there is not enough seating, though it still poses safety concerns. Using electronic devices is generally permissible, as long as they do not disturb other passengers. Engaging in conversation is a normal activity and does not present a safety risk as long as it is conducted at a reasonable volume. Thus, prohibiting occupancy in the vestibule specifically caters to maintaining a safe environment for all passengers onboard.