Cat eyes, also known as road studs, are retroreflective safety devices used for marking roads lines. It is the first of a range of elevated pavement markers. In 1933, Percy Shaw in England invented the Cat’s Eyes. It is made up of reflective glass spheres inside a rubber and cast iron housing. It exists in different colors, each having different meanings in different parts of the world while serving different purposes.

This article highlights how Cat’s Eyes or road studs work and provides a guide on understanding the meaning of these road studs and their uses in different parts of the world.

Guide To Understanding Cat’s Eyes

Every unit of road stud is complex and also dynamic. They are each designed to serve a variety of clever functions, and they comprise of:

  • Metal housing part: This part protects the device while producing an audible sound every time a car passes over it.
  • Fixed rubber wiper: This part clears off the glass when pressed under the road.
  • Reflective glass

Road studs are retro-reflective, which means they can redirect light back to their source with minimum scattering, making it very visible for moving cars. Raised pavement markers exist in different colors: some colors have similar meanings with painted road conventions, while other colors are used to relay information to people in the know.

To better understand how road studs work, here’s a highlight of their uses.

  • Road studs can be used as indicators: Road studs can inform incoming cars of what is ahead. For example, they can be used to pre-inform cars of a dead end.
  • It can be used for directions: Road studs can be used to guide and show travelers the right direction.
  • It can be used as a map for locating some facilities 

Although the uses of road studs are similar worldwide, the color usage may vary from one place to another.

General Meaning Of Stud Colors 

In different times different colors of road studs have evolved for diverse purposes. But some colors have remained constant, having a universal meaning in almost every part of the world.


  • White: White studs are positioned in the middle of roads to mark lanes and show islands. 
  • Yellow: Often positioned along the edges of roads, yellow studs are used as medians and road dividers.
  • Red: Red studs are placed along the bard shoulder of motorways.
  • Blue: Mainly used for emergency car pull-offs and slip roads. The police also use the blue stud to park their cars while monitoring busy traffic.
  • Green: It is used to indicate places with entrances or exits. It aids in marking mirror side roads and also in junctions to aid joining or leaving slip roads.



In general, cat eyes can send different messages using different colors, but you need to understand these road studs to know what they signify. Note that different colors can also be combined to send multiple messages. Cat eyes are easy to read, and their benefits are critical for the safety of all road users.

This article has highlighted some essential information you should know about cat eyes, their uses, and how to understand their colors.