About Us: Slow Moving Vehicle Sign

Slow Moving Vehicle Sign

A Historical Perspective of the SMV Emblem

In the late 1950s, a 10-year retrospective study of fatal tractor accidents was conducted by Walter McClure and Ben Lamp, both of the Department of Agricultural Engineering at The Ohio State University (AEOSU), to understand their nature and causes. Their research indicated a significant number of fatalities related to highway travel of slow moving vehicles (SMV). A research proposal written by Ken Harkness (AEOSU), and funded through the Automotive Safety Foundation (1961-62), further focused on understanding SMV accidents and resulted in the development of a unique SMV emblem. Early data estimated that 65 percent of the motor vehicle accidents involving SMVs were rear-end collisions. The Ohio State Highway Patrol, county sheriffs, and municipal police cooperated in research by gathering detailed data on 708 SMV accidents.

In 1962, under the supervision of Ken Harkness, the design and testing of the SMV emblem was completed. A 1/16 scale highway simulator had been constructed to test human recognition rates of different shapes and colors mounted on simulated SMVs. After testing various designs, a triangular-shaped emblem with a 12-inch-high fluorescent orange center and three 1 ¾-inch-wide red reflective boarders was determined to be the most effective design for day and night visual identification.

The Goodyear Rubber and Tire Company sponsored initial public exposure to the SMV emblem in 1962. An emblem mounted on the back of a farm wagon and towed by a Ford tractor made a 3,689-mile trip from Portland, Maine to San Diego, California.

The first formal introduction of the SMV emblem was at a University of Iowa Invitational Safety Seminar in 1962. Carlton Zink of Deere and Company then became an avid promoter of the SMV emblem and played a major role in the adoption of the emblem by the American Society of Agricultural Engineers (ASAE).

In 1963 Novice G. Fawcett, President of The Ohio State University, dedicated the SMV emblem to the public. Also in 1963, the Agricultural Engineering Journal printed its first article with color illustrations about the SMV emblem. The National Safety Council promoted the adoption of the emblem and awarded a Certificate of Commendation to Ken Harkness.

In less than two years from the emblem’s first date of availability, Nebraska, Michigan, Ohio, and Vermont adopted legislation requiring the emblem to be used on SMVs. Safety Leader Bill Stuckey, an Ohio Farm and Home Safety Committee member spearheaded the adoption of the SMV emblem in Ohio. In 1967 the Canadian Standards Association adopted the SMV emblem as a CSA Standard. In 1971 the SMV emblem became the first ASAE standard to be adopted as a national standard by the American Nation Standards Institute (ANSI). In recognition for the research development of the SMV emblem, Ken Harkness was selected as a Charter Member of the Ohio Safety Hall of Fame in 1992.

In 1992 the American Society of Agricultural Engineers designated the development of the SMV emblem as an ASAE Historic Landmark.


SMV Sign Timeline

  • 1961 – 1963 Developed by Kenneth A. Harkness, Department of Agricultural Engineering at The Ohio State University campus
  • 1964 Became an ASABE Standard
  • 1968 Specified in national uniform vehicle code
  • 1971 First ASABE standard ratified by American National Standards Institute (ANSI)
    Became Occupation Safety and Health Act (OSHA) regulation
    Ohio Farm and Home Safety Committee provided leadership in achieving acceptance
  • Dedicated 1992

The ASAE Slow Moving Vehicle commemorative plaque is located in the Agricultural Engineering Building on the Ohio State University in Columbus.


“The duty of the agricultural engineer to agriculture is plain. We should help the farmer in the better selection and use of equipment, and we should encourage standardization and the development of new types of equipment. We have educated the farmer and his wife to desire home comforts and sanitary features. But after we get the farmer to the point of using all these improvements, we must show him how to pay for them.”

Frederick W. Ives
18th President of ASAE
Chairman, OSU Department of Agricultural Engineering