How are movements controlled within an interlocking?

Movements within an interlocking are controlled by interconnected signals and appliances. This system ensures that various tracks and switches can operate in a coordinated manner, enhancing safety and efficiency in train operations. The interlocking system uses signals to indicate the status of tracks and switches, preventing conflicting movements that could lead to accidents.

Each element within the interlocking is designed to work in conjunction with others, meaning that when one signal changes, it can trigger changes in other signals and track configurations automatically. This interconnected nature allows for complex routing of trains while maintaining strict adherence to safety protocols.

The other options do not accurately represent how interlockings operate. Random signals would not provide the structured safety required in train operations. Predefined routes, while necessary, do not encompass the complete functionality of interlocking systems, as they rely on the signals and appliances to execute those routes safely. Manual block systems also do not capture the full capability of interlockings, which are predominantly automated and designed to minimize human error.