Which relay is described as 'Reverse traffic indicator relay'?

• A. RWP
• B. RWR
• C. RFK
• D. RN

Answer: (C)

Think about what a “Reverse traffic indicator relay” actually does: it powers or drives an indicator to show when traffic is moving in the opposite direction, signaling a reversal in the expected flow of trains. The relay that matches this purpose in the typical signaling relay family is the one designated for reverse-traffic indication. Its coil is energized by reverse-direction conditions, and its contacts feed the indicator device so operators can see that trains are traveling in the reverse direction.

That’s why the RFK relay is the best fit for this description—its function is specifically tied to indicating reverse traffic. The other relays handle different duties in the signaling system and aren’t described as the reverse-traffic indicator, so they don’t align with this description.