After an emergency stop, what signal must the train operator receive from the conductor before starting the train again?

In the context of train operations, safety procedures are critical, particularly after an emergency stop. The requirement for a train operator to receive a specific signal from the conductor before restarting the train is based on ensuring that all safety protocols are reflected in the communication between crew members.

Two long buzzer signals serve as a standardized and clear audible confirmation that it is safe to proceed. This signal indicates to the operator that the conductor has assessed the situation after the emergency stop, ensuring that it is safe to resume operations. This level of communication minimizes the risk of restarting the train before any potential hazards or issues have been addressed.

Other signals and options, while they may relate to different operational contexts, do not meet the specific criteria for communication following an emergency stop in this scenario. The emphasis is on having a clear and unmistakable signal from the conductor, which is met by the two long buzzer signals, thus contributing to safe train operations.