Manual on Uniform Traffic Control Devices

The Manual on Uniform Traffic Control Devices (MUTCD) is a document issued by the Federal Highway Administration (FHWA) of the United States Department of Transportation (USDOT) to specify the standards by which traffic signs, road surface markings, and signals are designed, installed, and used. These specifications include the shapes, colors, and fonts used in road markings and signs. In the United States, all traffic control devices must legally conform to these standards. The manual is used by state and local agencies as well as private construction firms to ensure that the traffic control devices they use conform to the national standard. While some state agencies have developed their own sets of standards, including their own MUTCDs, these must substantially conform to the federal MUTCD.

The National Committee on Uniform Traffic Control Devices (NCUTCD) advises the FHWA on additions, revisions, and changes to the MUTCD.

At the start of the 20th century—the early days of the rural highway—each road was promoted and maintained by automobile clubs of private individuals, who generated revenue through club membership and increased business along cross-country routes. However, each highway had its own set of signage, usually designed to promote the highway rather than to assist in the direction and safety of travelers. In fact, conflicts between these automobile clubs frequently led to multiple sets of signs—sometimes as many as eleven—being erected on the same highway.

Government action to begin resolving the wide variety of signage that had cropped up did not occur until the early 1920s, when groups from Indiana, Minnesota, and Wisconsin began surveying the existing road signs in order to develop a standard. They reported their findings to the Mississippi Valley Association of Highway Departments, which adopted the report's suggestions for the shapes to be used for road signs. These suggestions included the familiar circular railroad crossing sign and octagonal stop sign.

In 1927, the American Association of State Highway Officials, or AASHO, published the Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs to set standards for traffic control devices used on rural roads. This was followed by the Manual on Street Traffic Signs, Signals, and Markings, which set similar standards for urban settings. While these manuals set similar standards for each environment, the use of two manuals was decided to be unwieldy, and so the AASHO began work in 1932 with the National Conference on Street and Highway Safety, or NCSHS, to develop a uniform standard for all settings. This standard was the MUTCD.

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