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History of Cats Eyes and Their Function for the Road User


The Cat's Eye is a safety device and is used on 99 per cent of roads in the UK. The device was invented by Percy Shaw, who worked as a road-mender. The story behind the invention is quite a famous tale.

Percy Shaw Invented Cats Eyes

It is said that Shaw was driving home at night in the fog in 1933 when he reached a dangerous part of the road. Shaw claimed that at night he drove by using the reflection that his car headlights gave off in the tram tracks. But on this night in 1933 the fog was so bad that there was no reflection off the tracks and he could not make out where the road turned into the hillside. That is until he had the fortune of spotting his headlights reflecting back from the eyes of a stray cat that was sat by the road.

This was when it clicked that it would be a brilliant idea to replicate the reflection of Cat's Eyes to guide drivers along dark and dangerous roads. Shaw realised that as the car was becoming more popular and more motorists would want to drive at night - they would need a guide as headlights would not be enough to keep them safe.


Patent Registered for Cat's Eyes

Shaw registered the patent for the Cat's Eye in 1934 but it took several years to design what is known as the Cat's Eye. It took him so long because not only did he make it bright enough to illuminate the road at night, he also made it tough enough to withstand all weathers and vehicles driving over the top of it.

It was not until 1937 however, that Percy Shaw won the contract from the government to mass-produce the Cat's Eyes. Shaw made the road safety device from four glass beads, a rubber moulding and a cast iron base. To give off the best possible reflections Shaw decided that it was best to position the glass beads in pairs and face them in opposite directions. This was all integrated in an elasticated rubber moulding, which was firmly attached to a cast iron base. To keep the device in place it was buried and fixed in position with asphalt. Shaw made his Cat's Eyes really tough, even if vehicles drove over them - the rubber was shrunk into the road and the glass beads dropped safely beneath the road surface and remained undamaged.

Shaw even made them to cleanse themselves with the help of a little rain-water – the cast iron base collected the rainwater and whenever a vehicle ran over the top of the Cats Eye, the weight pushed the dome down and then the rainwater would automatically wash the glass beads keeping them clean and motorists safe. Shaw’s company Reflecting Roadstuds at its peak made over one million Cats Eyes a year and exported them across the globe.

There are variations of the original Cats Eye on UK roads, these are noted below:

  • The original Cats Eyes are white studs that separate lanes or the middle of the road.
  • Red studs warn motorists that they are close to the left edge of the road.
  • Amber studs warn drivers of the central reservation of a dual carriageway or motorway.
  • Green studs signify the edge of the main carriageway where rest-areas and access roads exit the main road.
  • Green/yellow studs warn drivers that there are temporary adjustments to lane layouts, e.g. where roadwork’s are taking place.

Disclaimer: The information in the article is for general purpose information only and should not be constituted as legal advice. This article has been produced by a third party and Jardine Motors does not take any responsibility for the completeness, accuracy, or reliability with respect to the website or the information provided. Article last updated March 2016.