What must the motorman do if no route or call-on is given after standing at a home signal for a while?

The correct action for a motorman who has been waiting at a home signal without receiving a route or call-on is to signal for a signal maintainer and call the desk trainmaster. This course of action is essential for safety and operational efficiency. Standing at a signal without any indication of movement can indicate a problem, and it’s important to address potential issues promptly.

By signaling for a signal maintainer, the motorman ensures that any malfunction or error with the signal can be checked and corrected by a qualified technician. Additionally, notifying the desk trainmaster allows for coordination of the situation and further instructions to manage any disruptions in the service. This proactive approach ensures that the train can safely and efficiently continue its journey once the signal issues are clarified.

The other options do not provide the appropriate response to the situation. Waiting for further instructions from the control tower could lead to unnecessary delays, without taking action to address the signal issue. Checking the route request buttons for errors may not be relevant if the signal itself is malfunctioning, and continuing to wait until the signal changes could lead to a dangerous situation if the signal cannot change due to an underlying problem. Hence, the correct response is to take immediate action by calling for assistance.