In which situation is the switch required to be inspected manually?

The requirement for a manual inspection of the switch when indicated by a signal is crucial for ensuring safety and operational efficiency. Signals are designed to convey important information about the status and condition of the track infrastructure, including switches. When a signal indicates a potential issue or alerts the crew to check for safety concerns, it necessitates manual inspection to verify that the switch is functioning correctly and to prevent any unsafe conditions that could lead to accidents or derailments.

In this scenario, trusting a signal prompts a proactive approach to safety. It ensures that before any trains proceed through or around the switch, the crew has confirmed that the switch is set correctly and is operable. This practice is essential to maintaining safe railway operations.

In contrast, factors such as weather conditions, regular maintenance schedules, or crew member uncertainty do not inherently trigger a manual inspection as effectively as a signal does. In the instances of sunny days or scheduled maintenance, routine practices may be adequate without the need for immediate, manual checks unless a specific signal points to a concern. Similarly, while uncertainty may warrant caution, it is the clear directive from signals that necessitates the immediate attention of a manual inspection.