Which term refers to interconnected signal appliances?

The term that refers to interconnected signal appliances is interlocking. Interlocking is a critical system used in railway signaling that ensures the safe movement of trains by controlling signals and switches in a coordinated manner. It prevents conflicting movements through the use of interconnected devices, making certain that only one train can occupy a specific section of track at a time. This interdependence of signals and switches means that if one signal aspect changes due to the position of a switch or the status of another signal, it will automatically adjust to maintain safety protocols.

In practical terms, interlocking helps prevent accidents on railroads by ensuring that tracks are set correctly before a train is allowed to proceed. This system enhances operational safety and efficiency, critical aspects in railway management. The other concepts listed, while relevant to railway operations, do not specifically convey the idea of interconnected signaling systems in the same way that interlocking does.