Which relay code corresponds to the description 'Reverse switch position route selection relay, northward initiation'?

• A. RLP
• B. RN
• C. RVP
• D. RWK

Answer: (B)

The main idea is that relay codes in this system encode the function and the direction of action in a compact form. The description calls for a relay that handles a reverse switch position and uses that to initiate a route for trains moving north. The two-letter code that matches this combination is the one where the first letter signals a route/switch-related function and the second letter picks out the direction, northward. So this code precisely represents a reverse-switch, route-selection relay with northward initiation.

In practice, when the switch is in reverse, this relay activates to set the appropriate northbound route, coordinating with signals and track switches to guide trains safely in that direction. The other codes correspond to different relay types or functions, so they don’t describe the same reverse-switch, northward route-selection role.