Final answer:
If the automatic stop arm of a home signal does not go down after the train operator operates the lever or button twice (a call-on has been displayed), he must take appropriate action to ensure safety and contact the signal maintainer or dispatcher for further instructions.
Step-by-step explanation:
If the automatic stop arm of a home signal does not go down after the train operator operates the lever or button twice, it means that the call-on has not been acknowledged by the signaling system.
In this case, the train operator must take appropriate action to ensure the safety of the train and its passengers. One possible action the operator can take is to contact the signal maintainer or dispatcher to report the issue and get further instructions.
The automatic stop arm is an important safety feature of railway signaling systems. It indicates to the train operator that it is safe to proceed or stop based on the signals received from the control center. If the arm does not go down, it could mean that there is a malfunction in the signaling system, and the train operator should not proceed until the issue is resolved.