What does two long buzzer sounds indicate?

Two long buzzer sounds are typically used as a clear signal for operators to proceed. This auditory cue is designed to indicate that it is safe to continue moving, often following a verification that the track is clear ahead or that conditions are appropriate for movement.

In the context of train operations, such signals play a crucial role in maintaining safety and communication between personnel and onboard systems. A status of 'proceed' suggests that no immediate action must be taken to halt or slow down, reinforcing the importance of the sound as a standard operation protocol that train operators rely on.

Other options may suggest actions such as stopping or reducing speed, which are reserved for different warning signals indicating caution or immediate risks. Therefore, understanding these auditory signals is essential for the efficient and safe operation of trains.