Which term describes the arrangement that ensures train movements occur in proper sequence with interlocking rules?

• A. Interlocking (Int)
• B. Indication
• C. Pilot
• D. Cab Signal Indicator

Answer: (A)

Interlocking is the arrangement of signals, switches, and the devices that control them in a way that prevents conflicting train movements. It locks the relevant signals and track devices so that a route can only be cleared if it has been verified safe, and a conflicting route cannot be cleared simultaneously. This guarantees trains move in the correct order and that switches and signals cooperate to avoid collisions, even as routes are changed by a dispatcher or operator. The other terms describe parts of the signaling system rather than the safety-driven arrangement: indication is what the signal shows to the operator, a cab signal indicator is the cockpit display of signaling status, and pilot isn’t the term for the interlocking arrangement.