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The Evolution of MUTCD

Updated December 2023 for the Eleventh Edition of the MUTCD.

The Prologue and Part I of this article were developed from a series of articles by H. Gene Hawkins, Jr., published in the ITE Journal between 1991 and 1994. Additional information has been supplemented by FHWA.


Part II and the Epilogue were developed by FHWA.


Prologue

The arrival of the automobile in the early 1900s started a revolution in travel - and traffic control devices have developed to keep modern day travelers moving ever more safely and efficiently to their destinations. Road signs were the first traffic control devices to direct travelers on their journeys. The evolution of these road signs provides a fascinating insight not only into the evolution of traffic control devices, but also to the pace of economic and social development in our Nation.

The Horseless Carriage Arrives

It was a bit like the old saying about being "all dressed up, and no place to go." The early days of the automobile found intrepid "tourers" out for a drive, only to wind up losing their way because directional signs were either nonexistent or they were broken, unreadable, or knocked down. In fact, as early as 1899, horseless carriage owners in New York City met at the Waldorf-Astoria Hotel for the purpose of forming an automobile club—the predecessor of the American Automobile Association—and part of their function was to place and maintain signs on principal local highways to guide drivers through the area or to specific sites.

Records indicate that in 1905, the Buffalo Automobile Club installed an extensive signpost network in the New York State. In 1909, the Automobile Club of California undertook the task of signing the principal highways within a 250-mile radius of San Francisco. These could be actual signs, or perhaps they were colored bands around a utility pole. Similar clubs conducted comparable efforts in local areas around the Nation. Unfortunately, competition for signing certain popular routes was fierce and organizations became increasingly aggressive as to which club would sign which routes. One study noted that for 40 to 50 percent of the more traveled roads, it was common to encounter as many as 11 different signs for one single trail or route.

But First, Some Other Firsts

While automobile clubs were busy developing early road signs, other entities were developing devices to control the flow of traffic. For example:

  • 1911, a centerline is painted on a Michigan road.
  • 1914, the first electric traffic signal is installed in Cleveland.
  • 1915, the first STOP sign appears in Detroit.
  • 1916, the Federal-Aid Act requires that a State have a highway department before it can get Federal money.
  • 1918, Wisconsin is the first state to erect official route signs as part of its maintenance functions.
  • 1920, the first 3-color traffic signal is installed in Detroit.

The First Signs of the Times

In the early 1920s, representatives from Wisconsin, Minnesota, and Indiana toured several States with the intent of developing a basis for uniform signs and road markings. The group reported its findings to the Mississippi Valley Association of Highway Departments (MVASHD) in 1923. Their efforts resulted in standards for sign shapes, many of which are still in use today.

These pioneers devised a plan to classify sign shapes according to the level of danger represented by highway situations. For example, round signs warned of approaching railroad crossings which, even then, represented the most potential danger to the driver. The octagon advised of the next level of danger—the need to STOP for intersections. Diamond signs indicated more ordinary conditions that required drivers to be cautious. Rectangular signs provided direction or other regulatory information. All signs were black letters on white background and were limited to 2 feet square—that was the maximum width of sign-making equipment. Because round and octagon shapes required the most cutting and wastage, they were chosen for the fewest installations. These shapes made sense because there was little illumination of signs and the rationale was that drivers would respond to the shape of the sign even when they couldn't see the letters.

In 1924, the First National Conference on Street and Highway Safety (NCSHS) improved on earlier efforts and proposed standardizing colors for traffic control devices. Again, many remain in use today. For example, the color red indicated STOP. while green signified proceed. Signs with black letters on a yellow background advised caution. Black and white signs providing information on direction and distance were specified for every intersection and junction. One combination that didn't last was white letters on purple background, indicating an intersection!

The First Signing Manual

Also in 1924, the American Association of State Highway Officials (AASHO, now AASHTO) took earlier efforts one step further by issuing a report that combined the previous efforts to standardize sign shapes and colors. The report recognized the superior visibility of the yellow background and advised its adoption for all danger and caution signs, including the STOP sign. The use of red was rejected because of its inadequate visibility at night. This report was also the first to propose an official shield to mark and designate U. S. highways.

The importance of the AASHO report is that it became the basis for the first guidebook, Manual and Specifications for the Manufacture, Display, and Erection of U.S. Standard Road Markers and Signs, in 1927. However, this manual addressed only use and design for signs on rural roads. Following a national survey of existing traffic control devices, the NCSHS published the Manual on Street Traffic Signs, Signals, and Markings to address urban traffic control devices. This manual corresponded with the AASHO rural manual, except that material also addressed traffic signals, pavement markings, and safety zones. The manual also allowed smaller signs in urban areas, and the STOP sign was modified to allow red letters on a yellow background. These two manuals would establish a firm foundation for the MUTCD, still yet to come…

Part I: The Early Years

MUTCD: The Beginning

1935, First Edition

It was immediately apparent that having two different manuals simply confused the attempt to standardize traffic control devices. Thus in 1932, AASHO and NCSHS formed the first Joint Committee on Uniform Traffic Control Devices. In 1935, the first MUTCD was published. More accurately, it was mimeographed. The demand for the manual was so great, that a printed version was published in 1937. The 1937 printed version was 166 pages; content was separated into four parts that addressed signs, markings, signals, and islands.

The 1935 edition set the standard for types of signs by classifying them as regulatory, warning, or guide signs. Regulatory signs were black on white rectangles (except the STOP sign was black on yellow or yellow on a red octagon); diamond-shaped slow-type signs warned drivers to slow down; signs that cautioned were square. The manual also promoted using symbols on signs because nighttime roadway illumination was becoming more common.

The 1935 MUTCD also defined some pavement markings. For example, centerlines were required only on approaches to hill crests with a clear view of less than 500 feet, short-radius curves, curves with restricted view, or pavements wider than 40 feet. Acceptable colors for centerlines were white, yellow, or black, depending on which provided the greatest contrast. It also supplied much-needed clarification on the number, color, and meaning of signal indications. The 3-color signal was adopted as the standard for signal lenses.

On November 7, 1935, the first edition of MUTCD was approved as a National standard by the American Standards Institute (now the American National Standards Institute).

MUTCD Editions Reflect Life in America

The 1935 MUTCD responded to the need for a manual that standardized the use and design of traffic control devices. As the Nation grew and changed, the MUTCD has grown and changed. The Manual has been revised at least once in every decade since to reflect that growth and change.

Early revisions were just that: a separate compendium itemizing each change to an existing edition. Current editions were not reformatted or reprinted to incorporate the new changes into the content. For example, in 1939, the Joint Committee issued a 25-page revision to the 1935 edition. The revision recommended changes for sign illumination, speed signs, no-passing zone pavement markings, signal warrants, and pedestrian signals. And, although illumination was recommended, white reflectors (red for Stop signs) could be used to illuminate all signs.

1942, Second Edition

The 1942, 208-page, MUTCD described the types of traffic control devices to be used during blackout conditions resulting from the war. Traffic control standards were not relaxed for blackout conditions, but rather special blackout devices were to be used where necessary. For example, reflectorized beads were required for use on all pavement markings required for blackout conditions. Pavement markings were also used in lieu of many signs that would normally be illuminated. This, by the way, was the advent of using word messages in pavement markings. The 1942 MUTCD was subtitled the “War Emergency Edition” and it was prepared “with the advice and assistance of the War Department and Office of Civilian Defense.”

1948, Third Edition

As the end of the war neared, traffic engineers realized that the MUTCD had to be completely rewritten. Work on a peacetime edition began in 1944, and a new edition of the MUTCD was published in 1948. The major format change in the postwar edition was reorganizing material so that every traffic control device was addressed in only one place. The 1948 Edition also represents the expansion in scope from mainly regulatory and warning signs to including guide signs. There was also a concerted effort to simplify word signs, and a rounded-letter alphabet—the upper-case letter forms of today’s Standard Alphabets, Series A through F—was adopted as standard for all signs.

The 1954 15-page revision to the 1948 MUTCD included 47 changes and a brief description of each. The most significant change is that the color for the STOP sign was white letters on red background, which resulted primarily from the development of new fade-resistant finishes that could also provide nighttime visibility. In addition to establishing red as the now-familiar color, the allowance of secondary messages on STOP signs was discontinued. Also significant is the introduction of the YIELD sign, the original version a black-on-yellow downward-pointing triangle with the legend YIELD RIGHT OF WAY. The revision also recommended generally limiting the use of Series A and B of the Standard Alphabets—the narrowest of the letter forms—to street name and parking signs.

New MUTCD Editions Signal America on the Move

1961, Fourth Edition

Changes incorporated into the 1961 MUTCD truly reflected a changing America. The Manual was 333 pages long and introduced three new areas. A new part addressed construction and maintenance operations. A major new chapter addressed needs of the new Interstate Highway System, adopting the use of white letters on green backgrounds for guide signs, blue backgrounds for rest area and roadside area signs, the use of upper- and lower-case letters for destination names, having been established earlier in a separate AASHO manual. Finally, there was a new chapter included for civil defense signing. In addition, Series A, the narrowest of the Standard Alphabets, was expressly discontinued.

Part II: FHWA Becomes the Custodian of the MUTCD

In response to the realities of a truly connected and seamless roadway transportation system, the Highway Safety Act of 1966 granted authority to the Secretary of the newly formed U. S. Department of Transportation to establish the national standards for traffic control devices. This meant that compliance with the MUTCD would become mandatory throughout the United States. This action recognized that providing clear, consistent, uniform messaging to road users on a national level is an effective, key component in fostering a safe travel environment. The MUTCD was codified in law for the express purpose of promoting the “safe and efficient utilization” of the nation’s system of roads—for all its users.

1971, Fifth Edition

A completely rewritten MUTCD premiered in 1971. Some of the most significant changes included adding definitions of the terms, "should," "shall," and "may." Orange was designated for construction signing, yellow markings separated opposing traffic, and there was a wider use of symbol signs. School signs were also adopted. The FHWA revised the 1971 MUTCD eight times by publishing a compendium of Official Rulings on requests that listed the individual revisions.

1978, Sixth Edition

The 1978 MUTCD contained two new parts that addressed highway-rail grade crossings and traffic control for bicycle facilities. There were also revisions addressing the fundamental safety principles concerning work zones, the need for traffic control plans, and an upgraded section on barricades and channelizing devices. New illustrations reinforced the signing and pavement marking standards. The 1978 MUTCD was published in loose-leaf format in a binder. FHWA revised this edition four times by issuing revised pages.

1988, Seventh Edition

The FHWA published the 1988 MUTCD as a bound document to provide an up-to-date Manual as the process of using loose-leaf pages to update the Manual had not worked as well as expected. The FHWA revised the 1988 MUTCD seven times.

In 1989, a blue-ribbon panel evaluated the MUTCD and recommended reformatting and rewriting the Manual to clarify language and intent. By early 1992, FHWA announced its intent to pursue such an effort. Throughout the 1990s, a number of Notices of Proposed Amendments for a significantly revised MUTCD were published in the Federal Register while several concurrent rulemaking efforts were focused on revisions of the 1988 MUTCD.

The MUTCD Enters a New Millennium

2000, Eighth Edition

The 2000 MUTCD represented a major change from its antecedents. Branded the “Millennium Edition,” it organized content into Standard, Guidance, Option, and Support provisions with those headings clearly labeled in every instance. This edition was the first to be available to the public on the FHWA Web site and the first to be dual-dimensioned, showing the primary dimensions in the International System of Units (Metric), along with the equivalent U. S. Customary units for reference. Organizational changes included removing the part on islands (Part 5) and replacing it with low-volume roads and adding a new part for highway-light rail transit grade crossings. The 2000 MUTCD added new content on in-roadway lights and accessible pedestrian signals to improve pedestrian crossing safety. In addition to the changes in the format and content of the 2000 MUTCD, FHWA transitioned exclusively to an electronic Web format and discontinued the printing of hard copies of the MUTCD. The FHWA provided the MUTCD in PDF and HTML formats that could be accessed free of charge. Those who wished to purchase printed copies of the MUTCD could do so from a number of professional and trade organizations, including AASHTO, ARTBA, ATSSA, and ITE.

2003, Ninth Edition

The 2003 MUTCD was originally envisioned primarily for the purpose of addressing errata in the 2000 MUTCD inherent in the efforts to combine the overall volume of changes with the first fully electronic production and deployment of that update. Nonetheless, the opportunity to make real strides in safety and operation was seized upon with a number of new advancements that were supported by experimentation and other research. Significant changes in the 2003 MUTCD included the addition of pedestrian countdown signals, improved accessibility in work zones, and the introduction of fluorescent pink as the sign color for incident management signs. Minimum levels of sign retroreflectivity were added to the MUTCD as one of the two revisions of this edition.

Improving Uniformity

To further the goal of achieving basic uniformity, in 2006, a revision to the Code of Federal Regulations formally defined the terms, “open to public travel” and “substantial conformance,” as applied to the MUTCD. While these terms had been in use and applied to the MUTCD for many years, they were not well-defined. The 2009 MUTCD would become the first under which these terms were formally defined and applied, providing transportation agencies a clearer picture of how and when their own standards and policies could be refined further from those in the National MUTCD, and how and where they apply.

2009, Tenth Edition

The 2009 MUTCD—the tenth edition, entering the year of its diamond jubilee—introduced new content and expanded existing content to improve uniformity, embrace all road users including an aging population, and accommodate innovation. New content included toll roads, managed lanes, pedestrian hybrid beacons, flashing yellow arrow, and changeable message signs. This edition required exclusively the use of symbolic indications for pedestrian signals and increased the sizes of many signs to make them more legible, along with many improvements in criteria to improve safety. This edition introduced the numbering of individual paragraphs and reverted to the use of U. S. Customary units only, eliminating the dual-dimensioning of the 2000 and 2003 MUTCDs. Minimum levels of pavement marking retroreflectivity were added to the MUTCD as the third revision of this edition.

2023, 11th Edition

In late 2020, FHWA published a Notice of Proposed Amendments for a new edition of the MUTCD. In the year following the publication of the NPA, the Infrastructure Investment and Jobs Act was passed. This legislation established a required quadrennial update cycle for the MUTCD so that it could better keep pace with evolving technologies and changing travel habits and needs. In addition, the statutory language in the U. S. Code was amended to reflect the fact that traffic control devices—and the MUTCD—serve a human-centered purpose, making explicit reference to the “safety, inclusion, and mobility of all users.” On December 19, 2023—nearly three years after the publication of the NPA—the final rule for the 11th Edition of the MUTCD was published. In this new edition are many advancements, including improved and expanded criteria for setting appropriate speed limits in differing contexts and environments, changes in warrants for traffic signals, colored pavements for bike lanes and transit lanes, and a completely new specific service sign category for electric vehicle charging. A completely new part on automated vehicles replaced low-volume roads as Part 5, with the existing provisions consolidated into their respective primary chapters thereby reducing a considerable amount of redundant content.

Epilogue

Will the MUTCD ever be “done”?

“What’s past is prologue.” Just as the world changes, so, too, does the MUTCD along with it. Maturing and developing technologies and changing trends—in travel patterns, people’s preferences and priorities—mean that there is always room for improvement in the MUTCD to respond to a changing environment. In this regard, the MUTCD is never really “done.” It is a document that evolves with the times.

Although not a “live” document in which changes are made at will, the MUTCD is a living document with an established, open process that offers the public the opportunity to weigh in on contemplated changes before they are adopted, and allows agencies time to adopt and implement changes in a systematic, manageable way that causes the least disruption to the traveling public. And with its established processes for evaluating new concepts, the ability to issue official interpretations of its provisions, and advance proven concepts through interim approvals, the MUTCD continues to be responsive to traveler needs even between new editions.