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. 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. A white background indicates a regulatory sign; yellow conveys a general warning message; green shows permitted traffic movements or directional guidance; fluorescent yellow/green indicates pedestrian crossings and school zones; orange is used for warning and guidance in roadway work zones; coral is used for incident management signs;** blue indicates road user services, tourist information, and evacuation routes; and brown is for guidance to sites of public recreation or cultural interest.
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. 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.
Test your Sign IQ by taking the interactive shape and color quiz available on the web at https://mutcd.fhwa.dot.gov. On the navigation bar under Knowledge, select Sign Shape/Color.
Standards for the sign design and application of the signs shown here as well as for other traffic control devices are contained in the Manual on Uniform Traffic Control Devices (MUTCD). Dimension drawings for signs can be found in the Standard Highway Signs book. Both of these books are available in electronic format online at https://mutcd.fhwa.dot.gov. This web site also contains information on standard lettering used on highway signs and pavement markings and on highway sign color specifications.
Hard copies of the MUTCD can be purchased from the American Association of State Highway and Transportation Officials (http://www.aashto.org); the Institute of Transportation Engineers (http://www.ite.org); the American Traffic Safety Services Association (http://www.atssa.com); and the US Government Printing Office (http://www.gpo.gov). The Standard Highway Signs book can be purchase from the US Government Printing Office and the American Traffic Safety Services Association through the web sites listed above.
Prepared in 2002 by the
US Department of Transportation
Federal Highway Administration
Office of Transportation Operations
*This sign was anticipated for inclusion in the 2003 edition of the MUTCD at the time of this printing.
**The use of coral for incident management signs was anticipated for inclusion in the 2003 edition of the MUTCD at the time of this printing.
United States Department of Transportation - Federal Highway Administration