A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, glass, metal, ceramic, thermoplastic paint, and come in a variety of shapes and colors.

Some other names for specific types of raised pavement markers include convex vibration lines, Botts' dots, Delineators, Reflectors, Cat's Eyes, IPL (In Pavement Light), Road Studs, or Road Turtles. At SERNIS, we call it Road Studs.

There are two types of Road Studs: with passive lighting and with active lighting.

 

Road Studs Types

Road Studs with Passive Lighting: These Road Studs have reflectors on their sides. They look like they are lighting but in reality, they just reflect the light of vehicles' headlights. This lighting reflective road stud includes a lens or sheeting that enhances their visibility by retroreflecting automotive headlights.

 

Road Studs with Active Lighting: These Road Studs contain LEDs, a battery, a circuit, and, in some cases, a solar panel. These Road Studs may be powered by solar or electricity. The wired studs feature pre-programmed operating modes and timings (you can use PC500 controller). The solar studs light up automatically at night, and the solar panel charges the battery in it throughout the day, which lights the LEDs. The solar panel serves as a charging source as well as a sensor for detecting nighttime. The circuit in it controls everything.

Road Studs Applications

They can indicate out mild bends or curves in the road that a driver would miss at night since headlight illumination requires a point of reference.

They can be used to signal junctions without traffic lights, speed bumps, and pedestrian crossings so that drivers can slow down or stop as needed.

On highways, they are frequently used as lane markings as well as road divider indications.

 

Road Studs Curiosities

During World War II, Road Studs helped drivers with shielded headlights to see where they were going, allowing them to use roads to navigate safely since the German aircraft could not see the vehicle headlights. Since then, Road Studs have been a common sight on UK roadways.

The name "Cat's Eye" is derived from Percy Shaw's inspiration for the device: the reflection from a cat's eyes while driving home one misty night.

 
Road Studs Colors Meanings (UK example)

• The original Cat’s Eyes are white road studs that separate lanes or the center of the road.
• Red road studs alert drivers when they are approaching the left edge of the road.
• Amber road studs alert drivers of a dual road or a highway’s center reserve.
• Green road studs mark the main highway's edge, where rest stops and access roads depart.
• Drivers are warned that there are green/yellow road studs ahead.

Road Studs History

The basic road stud, or Cat's Eye as it is more widely known, was created in 1933 by Percy Shaw, a road mender from Halifax (UK), and is currently used as a safety device all over the world.

The Cat's Eyes (the first reflective road stud) has a rather convoluted origin story. According to the most widely circulated version of the event, Percy Shaw (1890-1976), a Yorkshireman, was driving home one night in the dark (or fog, or dark and fog, depending on which version you hear) in 1933, and was having difficulty staying on the road, and would have plunged off the side of a hill if it hadn't been for a cat's eyes reflected in his headlights. That lead to the invention of the idea of mounting glass lenses on studs in the center of the road. Alternatively, following the removal of tram lines on the road near where he lived, Shaw noticed that he had been remaining in the proper spot on the road partially by observing the reflections of his headlights on the shining rails, giving him the idea of developing a reflective device for the road surface. Shaw subsequently informed BBC television presenter Alan Whicker that, rather than reflecting tram lines, he was inspired by road signs with glass lenses, therefore the cat's eye's origins remain somewhat clouded in mystery.

The reflecting glass lenses invented a few years earlier by Richard Hollins were put on the road signals in operation at the time of Shaw's encounter.

As vehicles were becoming increasingly popular, there were more people desiring to travel at night and they wanted more assistance to do it safely. That's when the idea of burying a simple reflective device in the road surface to guide drivers along dangerous roads waved came to him.

Shaw was not the first person to consider reflective glass lenses as a road safety measure. Frederick “Freddie” Lee (1904-1977) patented a similar idea for using colored glass lenses at the sides of roads to both mark out the road and warn of specific hazards such as junctions and steep gradients two years earlier, though his contribution to the history of road safety is unfortunately overlooked since Lee’s patent lapsed because he couldn't afford to pay it.

We can honor both Lee and Shaw without pitting them against one another. Lee for coming up with the idea initially, and Shaw for putting his invention into production and getting it on British roads.

Percy Shaw patented his innovation in 1934, and in 1937, he obtained a government contract to mass-produce the road stud.

Shaw has built the device out of two pairs of reflecting glass spheres - the 'eyes' - that are typically placed within a white rubber dome and fixed in a cast iron housing.

The blackouts of World War II (1939–1945) and the shuttered automobile headlights in use at the time showed the utility of Shaw's innovation and helped promote its widespread use in the United Kingdom. They got strong support after the war from a British Ministry of Transport group and their usage eventually expanded throughout the world, becoming crucial to road safety.

Cat's Eyes was named one of Britain's top ten design symbols in the BBC and Design Museum's Great British Design Quest in 2006.

The design has evolved slightly throughout time. Different casing forms accommodate varying traffic levels, and the white rubber inserts are now available in black as well.

Technology has also advanced in the field of 'reflecting' road studs, and in some situations, they are no longer reflective but are self-illuminated, or “active”. You can explore SERNIS range of road studs here.