Warning signs alert you to hazards ahead. Under the MUTCD they are yellow diamonds (or fluorescent yellow-green for pedestrians, bicycles, and schools), placed far enough before the hazard to let you react at highway speed. The correct test answer is almost always a change in speed or position, warning signs never grant right-of-way by themselves.
- Diamond: the standard warning shape.
- Pentagon (five-sided): school zones and school crossings.
- Round: railroad crossings ahead.
- Three-sided (triangle pointing down): yield, technically a regulatory sign, but tested alongside warnings.
- Placement distance scales with speed: about 100 feet before a hazard on low-speed streets, 500+ feet on highways.
| Sign | Meaning | Required action |
|---|
| Crossroad (+) | Intersection ahead | Scan, be ready to yield |
| T-symbol | Road ends ahead | Prepare to turn |
| Y-symbol | Side road joins | Watch for entering traffic |
| Circular arrows | Roundabout ahead | Slow, yield to left |
| Merge | Traffic merging from right | Adjust speed, open a gap |
| Lane ends | Your lane merges away | Signal early, change lanes |
| Two-way traffic | Divided highway ends | Keep right, expect oncoming |
- Curved arrow (left or right): reduce speed before the curve, the advisory speed plate below it is legally enforceable in many states when conditions are poor.
- Winding road: series of curves; hold a steady low speed.
- Hill (percent grade): steep descent, downshift, don’t ride the brakes.
- Narrow bridge / narrowing lanes: merge or slow early.
- Dead end / no outlet: no through road.
- Pedestrian crossing (fluorescent yellow-green): scan both sidewalks; yield laws apply inside the crosswalk.
- School crossing (pentagon): slow to the school-zone limit when children are present or lights flash.
- Bicycle crossing: expect bikes entering the roadway.
- Deer/moose crossing: most active at dawn and dusk; brake straight, never swerve.
- Truck crossing: trucks entering from side roads or ramps.
- Flagger ahead: obey the flagger over signals and signs.
- Slippery when wet: reduce speed in rain, this sign marks pavement that stays slick.
- Bump/dip, rough road: slow before, not during, the obstacle.
- Signal ahead: prepare to stop; don’t accelerate to beat it.
- Stop sign ahead: a yield is not enough, the next stop is full.
State exams test warning signs in two styles: name-the-meaning (picture of a deer, answer “animal crossing ahead”) and choose-the-action (“you see a merge sign, what should you do?”, adjust speed and position to let traffic enter). For the second style, memorize the response, not just the label. Signs with advisory speed plates always pair “slow to the advisory speed” answers with the hazard type.
| Trigger in question | Correct answer pattern |
|---|
| Yellow diamond, black arrow | Curve, slow before it |
| Yellow-green pentagon | School, expect children |
| Yellow circle, black X | Railroad, prepare to stop |
| Yellow diamond, two arrows joining | Merge or lane ends |
| Yellow diamond, signal symbol | Traffic signal ahead |
| Fluorescent yellow-green person | Pedestrian crossing |
| Shape | Color | Family | Example |
|---|
| Diamond | Yellow | Road geometry | Curve, hill, merge |
| Diamond | Yellow | Activity | Signal ahead, flagger |
| Pentagon | Fluorescent green | School | School crossing |
| Round | Yellow | Rail | Railroad advance |
| Rectangle | Yellow | Advisory plates | Speed, truck rollover |
| Rectangle | Orange | Work zones | Road work ahead |
| Triangle down | White/red | Yield (regulatory) | Yield |
| If the question mentions… | Pick… |
|---|
| Yellow diamond with arrows joining | Merge - adjust speed |
| Advisory speed plate | Slow to that speed before the hazard |
| Orange diamond | Construction zone - slow, follow flagger |
| Yellow circle with RR | Railroad - be ready to stop |
| Green person crossing | Pedestrian - yield in crosswalk |
| Truck on downgrade sign | Steep grade - downshift, check brakes |
| Deer sign | Stay alert dawn/dusk - brake straight |
