Which term refers to the fixed signals of an interlocking?

• A. Interlocking Signals
• B. Marker
• C. ACSES
• D. Foul Time

Answer: (A)

Interlocking signals are the fixed signals that sit at the entrances to and within an interlocking and are controlled by the interlocking to prevent conflicting movements. They are physically fixed in place and display the required aspect (stop, proceed, etc.) based on the interlocking’s routing. The other terms don’t refer to these signals: a marker is just a trackside reference, ACSES is a signaling/control system, and foul time relates to track occupancy—none of these describe the fixed interlocking signals.