Related Clues:

• Exit indicator, e.g.
• Speed limit posting, e.g.
• MERGE or SIGNAL AHEAD, e.g.
• Stop or yield, say
• 'It informs or instructs highway users (4,4)'
• It's an indication for drivers, by the way
• No overtaking, perhaps, as horseboxes like to hog lanes in the end
• Perhaps stop king doing as planned
• Aid to motorists
• Image to identify on a driver's license exam
• Stop Kildare Street figure!
• By the way, this is a useful source of information
• Info for drivers
• Source of information or instruction, by the way
• Stop or Yield, say