What must be ensured before a main track switch is considered operational?

Before a main track switch can be considered operational, it is crucial that the switch is lined correctly and locked. This ensures that the switch points are positioned accurately for the intended route, allowing trains to pass through safely. If the switch is not lined properly, a train could derail or end up on the wrong track, resulting in potential accidents and operational disruptions. The locking mechanism is also vital as it secures the switch in place, preventing any unintended movement while a train is passing. This combination of proper alignment and locking is essential for maintaining safety on the tracks.

While factors such as visibility, painting, and inspection are important to the overall maintenance and functionality of railways, they do not directly guarantee that the switch is ready for operation. Visibility ensures that personnel can see the switch from a distance, but it doesn't prevent operational hazards if the switch is not lined correctly. Painting might protect the switch from environmental wear but does not influence its immediate operational capability. Lastly, passing inspection might indicate that the switch meets certain standards, but unless it is correctly lined and locked at the moment a train approaches, it remains unsafe for use. Thus, ensuring that a switch is properly lined and locked is the fundamental requirement for its safe operation.