If a train operator receives a starting light but no buzzer signal, what action must they take?

When a train operator receives a starting light without a buzzer signal, the appropriate action is to start the train. The starting light indicates that it is safe to begin the journey, and the absence of the buzzer signal does not indicate a hazard or a need to halt operations.

In many operating procedures, the starting light serves as a primary indicator that the route is clear, and the absence of a buzzer often implies there are no further warnings or issues to address. Starting the train at this point is consistent with established protocols, assuming that prior conditions and signals have been adequately checked.

This action is predicated on the understanding that the operator is trained to interpret signals correctly and is aware of standard procedures regarding when and how to initiate movement. Therefore, the operator would proceed with the assumption that all conditions are safe for operation unless explicitly indicated otherwise by additional signals or instructions.

The other options do not align with the standard operating procedures in such scenarios. While waiting for a buzzer signal might seem prudent, the presence of the starting light generally allows for immediate action. Continuing with caution is also unnecessary when the starting light is clear. Checking the passenger load is a task that typically occurs before starting the journey rather than in response to signal indications.