Early 20th century 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. Conflicts between these clubs frequently led to multiple sets of signs—sometimes as many as eleven—being erected on the same highway. Government involvement did not occur until the late 1910s and early 1920s when groups from Indiana, Minnesota, and Wisconsin began surveying road to develop signage standards. They reported their findings to the Mississippi Valley Association of Highway Departments, which adopted their suggestions in 1922 for the shapes to be used for road signs. These suggestions included the familiar circular railroad crossing sign and octagonal stop sign. In January 1925,
Thomas Harris MacDonald, chief of the federal
Bureau of Public Roads, published an article in which he argued that developing highway transportation in the United States to the "highest degree" would require five major innovations. Among them were "uniform markings and signs" and a "uniform
color code". MacDonald argued that "drastic enforcement of uniform rules" as to "all those matters of law, regulation and safety devices which involve the human attributes in the operation of the vehicle" would improve safety on American highways, because in emergency situations, a driver and his vehicle must react as one on the basis of "reflex" and there is no time to think. Despite the title, this manual did not have any guidance on
pavement markings; In 1937, the manual was republished as a typeset document. The test strips were located along
Ohio State Route 104 near
Columbus,
U.S. Route 250 and
Virginia State Route 53 near
Charlottesville,
Minnesota State Highway 101 near
Minneapolis, and other roads in New York.
France,
Chile,
Turkey,
India, and
Southern Rhodesia reciprocated by installing MUTCD signs on their roads. In the US, the experiments attracted unexpected controversy and curious onlookers who posed a hazard. By September 1951, the experts working on the project were in favor of the American proposals for stop signs (at the time, black "STOP" text on a yellow octagon), "cross road", "left or right curve", and "intersection", but were still struggling to reach consensus on symbols for "narrow road", "bumpy or uneven surface", and "steep hill". In 1953, after cooperating with the UN conference's initial experiments, the United States declined to sign or ratify the UN's then-proposed protocol for a worldwide system of uniform road signs. In an essay published in the July 1965 edition of
The Atlantic Monthly, he argued that a lack of uniform standards between states contributed to highway deaths. For example, two of the worst deviations from the majority rule that no passing should be marked with a solid center line were Pennsylvania, which marked no-passing zones only with signs and not center lines, and Georgia, which marked them only with a yellow line on the shoulder. The penalty for non-compliance was a 10% reduction in funding. In turn, taking advantage of broad rulemaking powers granted in , the Department simply adopted the entire MUTCD by reference at . ((a)(1), also enacted in 1966, authorizes federal agencies to incorporate by reference technical standards published elsewhere, which means the agency may merely cite the standard and need not republish its entire text as part of the appropriate regulation.) Thus, what was formerly a quasi-official project became an official one. States are allowed to supplement the MUTCD but must remain in "substantial conformance" with the national MUTCD and adopt changes within two years after they are adopted by FHWA. The 1971 edition of the MUTCD included several significant standards. The MUTCD imposed a consistent color code for
road surface markings by requiring all center lines dividing opposing traffic on two-way roads to be always painted in yellow (instead of white, which was to always demarcate lanes moving in the same direction), and also required that all highway guide signs (not just those on interstate highways) contain white text on a green background. Orange was introduced as the standard color for traffic control in work zones. was a preference to adopt symbols on signs in lieu of words "as rapidly as public acceptance and other considerations permit." During what was then expected to be a transition period, the MUTCD allowed state highway departments to use optional explanatory word plaques with symbol signs and to continue using the previous standard word message signs in certain cases. Conner was active in the Joint Committee and also represented the United States at international meetings on road traffic safety. However, several American traffic safety experts were concerned that American drivers would not understand the Vienna Convention's symbols, which is why the MUTCD allowed for explanatory word plaques. Most of the repainting to the 1971 standard was done between 1971 and 1974, with a deadline of 1978 for the changeover of both the markings and signage. The U.S. adoption of several Vienna Convention-inspired symbol signs during the 1970s was a failure. For example, the lane drop symbol sign was criticized as baffling to U.S. drivers—who saw a "big milk bottle"—and therefore quite dangerous, since by definition it was supposed to be used in situations where drivers were about to run out of road and needed to merge into another lane immediately. American highway safety experts ridiculed it as the "Rain Ahead" sign. (The American "School Xing" symbol was later redesigned to depict an adult crossing together with a child.) However, several signs from the Vienna Convention were successfully adopted into the 1971 MUTCD, including the red "Yield" sign, which replaced the previous yellow version, and the "Do Not Enter" sign, which replaced a word-only version. Because the Vienna Convention version was circular, it was given a square backing to conform with the MUTCD shape for regulatory signs, and the words "DO NOT ENTER" were superimposed to ensure American driver comprehension. The 1971 MUTCD's preference for a rapid transition to symbols over words were removed in the 1978 MUTCD. After 1971, FHWA formally assumed responsibility for publishing the MUTCD. The 1971 MUTCD was revised eight times. In 1978, the MUTCD physical format was changed to a
ring binder whose revisions were published as replacement pages (i.e., an interfiled
looseleaf service). The tenth edition of the MUTCD was published in 2009, with revisions in 2012. This was the first editing to cover traffic control devices on private property. and the eleventh edition was released in 2023. This edition allowed painted red bus lanes, rules allowing more crosswalks and traffic signals, new rules for determining speed limits, signage for shoulders that are used part-time as traffic lanes, and new signage for
electric vehicle charging stations and
autonomous vehicles. RRFBs were previously on interim approval by FHWA since March 20, 2018. Transportation safety advocates criticized the changes as not going far enough to deal with a substantial spike in pedestrian fatalities, especially guidance setting speed limits
based on the 85th percentile of actual driving speeds. == Development ==