When is an assistant conductor permitted to pass communicating buzzer signals or hand signals to start the train?

An assistant conductor is permitted to pass communicating buzzer signals or hand signals to start the train when a conductor explicitly asks them to do so. This protocol ensures that the operation of the train remains coordinated and safe, as the conductor carries the primary responsibility for the safe movement of the train. By maintaining clear communication and following the conductor's instructions, the assistant conductor helps ensure that all actions taken are deliberate and in line with safety regulations and standard operating procedures.

The other scenarios do not provide the proper authority or structured communication needed for safe train operations. For example, relying on other staff members or passengers could lead to miscommunication, while emergency situations typically call for specific emergency procedures rather than routine signals.