If You’ve Seen One of These, You’ve Seen a Million

October 23, 1964

A 45-year-old Illinois engineer named Sidney Allen Heenan applied for a U.S. patent for a durable road safety device that remains in extensive use nationwide to further reduce motor vehicle accidents. The device, as outlined in his patent application, was a raised pavement reflector marker. These markers were designed for placement on roads to help safely guide traffic via such key functions as making road lanes more visible for drivers at night. On July 25, 1967, Heenan was granted U.S. Patent 3,332,327 for his invention.

Heenan was not the first person to develop this type of retroreflective safety device for roads. English inventor and businessman Percy Shaw had come up with a similar device, which was called the “cat’s eye” in reference to the superior nocturnal vision of felines, more than three decades earlier. In its original form, the cat’s eye consisted of two pairs of reflective glass spheres set within a white rubber dome mounted in a cast-iron container. Shaw received a United Kingdom patent for his invention in 1934 and a related U.S. patent five years later.

Heenan’s rendition of a raised pavement reflector marker, however, distinguished itself from the type created by Shaw — as well as an equally popular version devised by California Highways Division engineer Elbert Dysart Botts during the 1950s – for several key reasons. These reasons were emphasized by Ronald A. Sandler, who was instrumental in having Heenan named Inventor of the Year by the Intellectual Property Law Association of Chicago in 1994.

“A principal aspect of [Heenan’s] invention was the discovery that ordinary plastic (acrylic), which, although relatively soft, could be used on the roadway even though subject to the conflicting effects of tire wiping and abrasion,” explained Sandler. “The significance to highway users was early recognized by various publications of numerous state highway departments that began to adopt and use the Heenan pavement marker.” Heenan died in 1997 at the age of 78.

For more information on Sidney Allen Heenan’s patent for a raised pavement reflector marker, please check out https://patents.google.com/patent/US3332327.

Additional information on the development and uses of raised pavement reflector markers is available at https://99percentinvisible.org/article/decoding-cats-eyes-global-color-guide-reflective-road-markers/.

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