What does the School Speed Limit When Flashing sign mean?
The School Speed Limit When Flashing sign (MUTCD S5-1) is a school zone sign under the federal Manual on Uniform Traffic Control Devices, the national standard the states build from. The lower figure binds only while the beacon is lit, or inside the hours printed on the plaque. Outside that window the regular limit is the one you are held to.
Source: MUTCD 11th Edition, Part 7, Table 7B-1, checked 2026-09-09.
What shape and color is the School Speed Limit When Flashing sign?
| MUTCD code | S5-1 |
|---|---|
| Group | School zone signs |
| Shape | Vertical rectangle |
| Color | Fluorescent yellow-green SCHOOL panel above a white speed limit panel with black legend |
What a vertical rectangle means. Usually regulatory: a law you must obey. Speed limits, turn restrictions and parking rules take this shape. Rectangles are the loosely assigned outline in the system, though, so on this sign the shape alone does not tell you its family; the color and the legend do.
What fluorescent yellow-green means. Pedestrian, bicycle and school warnings. Reserved so those warnings cannot be mistaken for an ordinary hazard.
School zone signs. A pentagon means school and nothing else, so the outline alone answers the question. Fluorescent yellow-green is weaker evidence, because pedestrian and bicycle signs are allowed the same color, and that asymmetry is where the marks go.
What is the School Speed Limit When Flashing sign often mistaken for?
An ordinary Speed Limit sign (R2-1). The lower limit is not in force at all times, and the plaque under it defines when it applies: WHEN FLASHING (S4-4P), WHEN CHILDREN ARE PRESENT (S4-2P) or a time of day (S4-1P).
|  |
|---|---|
| GroupSchool zone signs | GroupRegulatory signs |
| ShapeVertical rectangle | ShapeVertical rectangle |
| ColorFluorescent yellow-green SCHOOL panel above a white speed limit panel with black legend | ColorWhite background, black legend and border |
| What it meansThe lower figure binds only while the beacon is lit, or inside the hours printed on the plaque. | What it meansA ceiling fixed by law, and it assumes the best case: dry pavement, clear sight lines, light traffic. |
Which signs get mistaken for the School Speed Limit When Flashing sign?
Reduced School Speed Limit AheadS4-5, S4-5aS5-1, the sign that actually imposes the limit. S4-5 is advance warning only.
What are the other school zone signs?
All 7 school zone signs on one page, or every US road sign by shape and color.
Test yourself on this sign and the rest of the set with a road signs practice test for Florida, Texas or California.
The artwork is the federal design itself, which the manual dedicates to the public domain in MUTCD 11th Edition, Part 1, Section 1D.06, checked 2026-09-09. The Interstate Shield, the 511 pictograph and the National Scenic Byway graphic are named exceptions and are not reproduced anywhere on this site.
Source: Manual on Uniform Traffic Control Devices, 11th Edition. Not affiliated with or endorsed by the Federal Highway Administration or any state agency.