The Manual on Uniform Traffic Control Devices (MUTCD) is the standard that dictates all traffic control device installations and maintenance across the United States. It covers every road open for public use - all highways, streets, and bike lanes.
MUTCD standards have been enforced since 1971 by the Federal Highway Administration under the United States Department of Transportation.
These standards keep all of the driving signs and symbols that you see on the road uniform, so there is no confusion between the driving signs and symbols from one state to another. By keeping signs and symbols uniform, safety is greatly increased for drivers and pedestrians on the road.
The shape of a MUTCD compliant sign is standardized to bring familiarity to drivers, and also to convey the level of importance to its message. Driving signs and symbols with more sides are typically more important to immediate safety.
Driving signs and symbols like stop signs (eight sides) and school crossing signs (five sides) warn drivers of immediate hazards, while square signs like those for street signs are less important for dangers as they are for direction.
The six shapes a driver is most likely to encounter for driving signs and symbols are:
- Octagon (stop signs)
- Pentagon (school warning signs)
- Triangle (yield signs)
- Diamond (warning and construction signs)
- Circle (railroad warning signs)
- Square (speed limit signs and parking signs)
For more information about the regulations on driving signs and symbols, visit the MUTCD's webpage.