Agriculture icon celebrates 60 years

Written by Ed Lentz, ANR Educator, Hancock County

Drivers may see the recognizable triangular orange symbol warning drivers of slow-moving vehicles in the area for the next two to four weeks as farmers gear up for crop planting. The emblem is required on farm vehicles moving less than 25 miles per hour and horse-drawn vehicles. What you may not know is that Ohio was an agricultural leader in the development of this SMV emblem.

In the late 1950s, two researchers in the Department of Agricultural Engineering of Ohio State University, Walter McClure and Ben Lamp, completed a 10-year retrospective study of fatal tractor accidents to understand the nature and causes of highway tractor collisions. They found a significant number of fatalities related to highway travel by slow-moving vehicles. Ohio State Highway Patrol, county sheriffs, and municipal police cooperated in a later study by gathering detailed data on 708 slow-moving vehicle accidents and estimated that 65% of the motor vehicle accidents involving slow-moving vehicles were rear-ended collisions.

As a result of these studies, an emblem was designed and evaluated for slow-moving vehicles in 1962 by a team of OSU Agricultural Engineers led by Ken Harkness. A 1/16 scale highway simulator had been constructed to assess human recognition rates of different shapes and colors mounted on simulated slow-moving vehicles. After testing various designs, a triangular-shaped emblem with a 12-inch-high fluorescent orange center and three 1 3/4-inch-wide reflective borders were determined to be the most effective design for day and night visual identification.

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 significant role in the adoption of the emblem by the American Society of Agricultural Engineers. 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.

Orange and Red Reflective Slow Moving Vehicle Sign

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 National Standards Institute. In recognition of the research and 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. This year, the SMV celebrates 60 years as a safety symbol to alert the motoring public when sharing the roads with agricultural equipment and horse-drawn vehicles. It has been adopted for use in other countries and is one of the most recognized emblems used by farmers and ranchers around the world. This website,, has more information on SMVs and agriculture safety, including the information used in this article.

Farm equipment will be on rural roads for the next month. Look for the SMV sign, slow down, and be prepared to suddenly come upon tractors, sprayers, and other farm vehicles on the road. Let us enjoy the arrival of spring weather, celebrate our agricultural heritage, and arrive at our travel destination safely.

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