Signal Ahead Sign: Get Ready for a Traffic Light
The signal ahead sign is a yellow diamond with a red, yellow and green traffic light symbol. It warns that there is a traffic signal ahead that you may not see in time, often because of a curve, a hill or high speeds. Ease off the gas, look for the signal and be ready to stop if it is yellow or red.
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Signal ahead quiz: 3 test-style questions
- A yellow diamond sign shows a traffic light symbol. What does it mean? The traffic signal ahead is not working / There is a traffic signal ahead; be prepared to stop / You have the right-of-way at the next intersection / Traffic lights are not used beyond this point. Answer: There is a traffic signal ahead; be prepared to stop. The signal ahead sign warns of a traffic light you may not see in time. It says nothing about the signal's color; be ready to stop.
- You approach a signal-controlled intersection and the light turns yellow. You should: Speed up to clear the intersection / Stop if you can do so safely; if you are too close to stop safely, proceed with caution / Stop immediately, even if you are already in the intersection / Treat it as a green light. Answer: Stop if you can do so safely; if you are too close to stop safely, proceed with caution. A steady yellow means the light is about to turn red. Stop if you can do it safely; never accelerate to beat the red.
- The traffic signal ahead is dark because of a power failure. You should: Drive through without slowing / Treat the intersection as an all-way stop / Yield only to vehicles on your right / Honk and proceed. Answer: Treat the intersection as an all-way stop. In most states a dark signal is treated as an all-way stop: stop completely and take turns.
What the signal ahead sign means
The Signal Ahead sign (MUTCD W3-3) is a yellow diamond with a symbol of a traffic signal showing red, yellow and green lenses. It does not tell you what color the light is. It tells you that a signal exists ahead and that you may not see it early enough on your own — for example after a curve, over the top of a hill, in a high-speed area, or where the signal is the first one after miles of open road.
Sometimes the sign comes with flashing yellow beacons and a plaque reading BE PREPARED TO STOP WHEN FLASHING. When the beacons flash, the light ahead is red or about to turn red.
What to do, step by step
- Take your foot off the gas and cover the brake.
- Look for the signal as soon as it comes into view and check its color.
- Check your mirrors so you know whether someone is following too closely.
- If it is red, stop at the stop line, before the crosswalk, or before the intersection if there are no markings.
- If it turns yellow, stop if you can do it safely. If you are too close to stop safely, continue through with care.
- If it is green, still scan the intersection for red-light runners and pedestrians before you enter.
Test traps
A common wrong answer is that the sign means the signal is broken. Another is that you can speed up to make the green light. Both are incorrect. Remember that the sign is yellow because it is a warning sign: it prepares you for the signal; the signal itself controls the intersection. If the signal is dark or flashing red, treat it like a stop sign; if it is flashing yellow, slow down and proceed with caution.
Where you see it
The sign is placed far enough before the intersection to give you time to stop from the usual speed of the road. It is common on rural highways entering a town, before signals hidden by curves or hills, and at new signals drivers are not used to. Red-light running is a serious cause of crashes at signals, which is why engineers add this early warning.
Related signs
The signal ahead sign belongs to a family with the stop ahead sign and the yield ahead sign. Also learn the no turn on red sign and review signal colors in our traffic lights guide.
Signal ahead sign FAQ
What does the signal ahead sign mean?
It warns that a traffic signal is ahead and may come into view late. Slow down, look for the light and be prepared to stop.
Does the signal ahead sign mean the light is red?
No. The symbol always shows all three colors. Only flashing beacons with a BE PREPARED TO STOP WHEN FLASHING plaque tell you the light ahead is red or turning red.
What should I do if the signal ahead is not working?
In most states, treat a dark signal as an all-way stop. Stop completely, then take turns with other drivers.
What should I do at a yellow light?
Stop if you can do so safely. If you are so close that you cannot stop safely, proceed through the intersection with caution. Never speed up to beat a red light.
Official sources
Keep studying
- Stop ahead sign
- No turn on red sign
- Traffic lights and pavement markings
- Traffic signals practice questions
- All U.S. road signs
- Practice tests by topic