Regulatory Signs: Speed Limits, Stop/Yield, Prohibitions, and Lane Use
What regulatory signs do
Regulatory signs are the white vertical rectangles with black legends that tell you what the law requires: speed limits, stop and yield, turn and lane restrictions, parking and truck prohibitions. A few regulatory signs use red and white, notably STOP, YIELD, DO NOT ENTER, and WRONG WAY. The exam tests whether you can read the sign, place it in the correct sign family, and apply it at the right point on the road.
Core rules
- A speed-limit sign gives the maximum legal speed in ideal conditions; slower is required in rain, snow, ice, or heavy traffic. North Dakota posts limits from 25 mph in many urban districts to 80 mph on rural interstate segments, but the posted number controls.
- STOP means a complete stop at the stop line, crosswalk, or edge of the intersecting roadway, then yield to traffic and pedestrians.
- YIELD means slow down and stop only if needed to let traffic or pedestrians go.
- Prohibition signs use a red circle and slash, or a word legend such as NO LEFT TURN, NO TRUCKS, or NO PARKING.
- Lane-use signs such as LEFT TURN ONLY or STRAIGHT ONLY assign the lane; do not change the assignment because traffic is light.
Worked example
You approach a green light and see a white sign with a left arrow inside a red circle and slash. The signal is green, but the sign prohibits left turns. Reasoning: the regulatory sign overrides the general permission to turn on green; you must go straight or follow another allowed movement. If you are already in a left-turn lane, you may have to continue and turn only where legal.
Traps
Treating YIELD as a full stop every time, or treating STOP as a rolling check. Ignoring plaques such as TRUCKS or NIGHT. Reading an advisory speed as a legal limit. Assuming a green light cancels a no-turn sign.