Roadway signs in the United States increasingly use symbols rather than words to convey their message. Symbols provide instant communication with roadway users, overcome language barriers, and are becoming standard for traffic control devices throughout the world.
LEARN TRAFFIC SIGNS - ROAD SIGNS WITH MEANINGS FOR KIDS AND ALL
Familiarity with symbols on traffic signs is important for every road user in order to maintain the safety and efficiency of our transportation facilities. The color of roadway signs is an important indicator of the information they contain.
The use of red on signs is limited to stop, yield, and prohibition signs. Sign shape can also alert roadway users to the type of information displayed on a sign.
Traffic regulations are conveyed in signs that are rectangular with the longer direction vertical or square.
Additional regulatory signs are octagons for stop and inverted triangles for yield. Diamond-shaped signs signify warnings. Rectangular signs with the longer direction horizontal provide guidance information.
Road Symbol Signs
Pentagons indicate school zones. A circular sign warns of a railroad crossing.
The illustration below shows how the shape and color of a sign indicate the nature of the message. Dimension drawings for signs can be found in the Standard Highway Signs book. This web site also contains information on standard lettering used on highway signs and pavement markings and on highway sign color specifications.