Origins of the Slow Moving Vehicle Sign

| Industry Insights

slow moving vehicle sign
Like many safety advancements, the slow moving vehicle sign developed in response to statistics that painted a very clear picture. In the 1960s, researchers at The Ohio State University noted that almost 2/3 of the highway fatalities involving slow moving equipment were rear-end collisions. Many of these fatalities occurred at night when drivers simply were unaware of tractors on the road until it was too late.

The researchers responded to this data by testing the visibility of different colors, materials, and shapes, seeking to achieve optimal visibility for daytime and nighttime driving.

How the Sign Got Its Distinctive Shape

The slow moving vehicle sign is instantly recognizable not just for its color scheme and reflectivity but also for its shape. The distinctive shape of the SMV emblem helps shed light on the practical nature of this enduring symbol.

While the emblem began as a regular equilateral triangle with a 12-inch fluorescent orange center, with 1 ¾” red reflective borders, necessity During testing, however, one of the graduate assistants working on the project repeatedly ripped his clothing on the corner of the emblem while climbing onto a rear-mount tractor on which the emblem had been fitted. Ironically, a safety symbol had become a safety hazard with its sharp corners. (As the story goes, his mother was also not happy about needing to repeatedly mend his clothing.) So it was off with the corners, and the unique shape of the SMV symbol has become one of the most recognizable safety signs for farmers and ranchers worldwide.

Developed (and modified) out of necessity, the SMV sign has saved countless lives over the last 53 years, and it will continue to save lives in years to come. As with many common-place safety measures, the creation and implementation of SMV signs began with individuals who recognized an avoidable hazard, and worked to prevent it.


Jepsen, Dee. “Slow, Simple, Safe!” AEM Product Safety and Compliance Seminar. Hyatt Regency, Shaumburg, IL. 28 Apr. 2014.

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