The best clue that a roadway is changing from multi-lane to single-lane is

• A. a rumble strip
• B. a warning sign
• C. a painted line
• D. a speed limit sign

Answer: (B)

When a roadway is about to go from several lanes down to one, the clearest cue is a warning sign indicating lane reduction or merge ahead. Warning signs are placed specifically to alert drivers to changes in road geometry in advance, giving you time to slow slightly, check mirrors, signal, and merge smoothly before the lane count changes. A rumble strip mainly serves to wake or alert drivers about hazards or the road edge, not to communicate lane counts. Painted lines show lane boundaries but don’t reliably indicate an upcoming reduction in the number of lanes. Speed limit signs tell you how fast to drive but not how many lanes will be available. So the warning sign is the best clue because it directly communicates the upcoming change in lanes.