Advisory Speed Plaque: The Yellow MPH Sign Explained
The advisory speed plaque is a yellow square with a speed such as 35 MPH, mounted below a warning sign. It shows the recommended maximum speed for that curve, turn or hazard in good conditions. In most states it is not a legal speed limit, but going faster than it is risky and can lead to a ticket for unsafe speed.
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Advisory speed quiz: 3 test-style questions
- A yellow square plaque reading 25 MPH is mounted under a curve sign. What does it mean? The legal speed limit for the rest of the road is 25 mph / 25 mph is the recommended maximum speed for the curve / The minimum speed is 25 mph / Only trucks must slow to 25 mph. Answer: 25 mph is the recommended maximum speed for the curve. A yellow speed plaque is advisory. It tells all drivers the safe speed for the hazard in good weather.
- Which sign shows a legal, enforceable speed limit? A yellow square plaque under a warning sign / A white rectangle reading SPEED LIMIT 45 / An orange diamond reading ROAD WORK AHEAD / A yellow diamond with a curved arrow. Answer: A white rectangle reading SPEED LIMIT 45. Speed limits are regulatory signs: black on white rectangles. Yellow speed plaques are warnings.
- It is raining hard and you approach a curve with a 40 MPH advisory plaque. You should: Drive exactly 40 mph / Drive slower than 40 mph if conditions require it / Drive the posted speed limit / Speed up to get through the curve quickly. Answer: Drive slower than 40 mph if conditions require it. Advisory speeds are set for good conditions. In rain, snow, fog or darkness, a lower speed may be necessary.
What the advisory speed plaque means
The Advisory Speed plaque (MUTCD W13-1P) is a yellow square with black numbers and the letters MPH. The “P” in its code means it is a plaque: it is never used alone but mounted below a warning sign, such as a curve sign, a turn sign or a winding road sign. It gives the recommended maximum speed for that specific hazard.
Road agencies set advisory speeds from engineering studies of how fast a typical vehicle can safely take the curve, and post them in 5 mph steps. Related signs exist for freeway exits and ramps: a vertical yellow rectangle reading EXIT 30 MPH or RAMP 25 MPH works the same way.
Advisory speed vs. speed limit
Even where the plaque is only a recommendation, every state has a basic speed law: you must never drive faster than is safe for conditions. If you crash or lose control above the advisory speed, you can be cited. See the speed limit sign page for regulatory limits.
| Advisory speed plaque | Speed limit sign | |
|---|---|---|
| Color and shape | Yellow square (or yellow vertical rectangle for exits and ramps) | White rectangle |
| Type | Warning | Regulatory |
| Applies to | One curve, turn or hazard | The road until the next limit sign |
| Legal effect | Recommendation in most states | Enforceable maximum |
What to do
- Read the plaque and the sign above it together: the plaque tells you how fast, the sign tells you why.
- Brake before the hazard so you reach the advisory speed while still on straight road.
- Go slower in rain, snow, ice, fog or darkness, or if you drive a tall or heavily loaded vehicle.
- Accelerate again only once you have passed the hazard.
Test traps
The most common trap is the question “Is the advisory speed a legal limit?” The best answer is that it is a recommended safe speed, while the basic speed law still applies. Another trap: the plaque does not cancel the speed limit. If the limit is 55 and the curve plaque says 35, the limit after the curve is still 55. Also, the advisory speed applies to all vehicles, not only trucks.
Related signs
Learn it together with the curve sign, the slippery when wet sign and the speed limit sign. Then read our guide to speed limits and following distance.
Advisory speed FAQ
Is the advisory speed a legal speed limit?
In most states, no. It is a recommended maximum for good conditions. You can still get a ticket under the basic speed law if you drive too fast for conditions.
Why is the advisory speed sign yellow?
Because it is part of a warning sign. Yellow is the color for general warnings; legal speed limits are on white regulatory signs.
Does the advisory speed apply to cars and trucks?
Yes, to all vehicles. Large trucks and vehicles with a high center of gravity often need to go even slower than the posted advisory speed.
What does an EXIT 30 MPH sign mean?
It is an advisory speed for a freeway exit ramp. Slow down to that speed in the deceleration lane, not on the main lanes of the freeway.
Official sources
Keep studying
- Curve sign
- Speed limit sign
- Winding road sign
- Speed limits and following distance
- Speed practice questions
- All U.S. road signs