Cat's eyes are one of those things most drivers see every single night but rarely think about. These small reflective road studs play a massive role in keeping motorists safe, particularly in the dark or during poor weather. Below, we cover what cat's eyes are, how they work, what the different colours mean, and why they remain essential to road safety across the UK.
What Are Cat's Eyes?
Cat's eyes are reflective road studs embedded into the road surface. They reflect vehicle headlights back towards the driver, helping to define lanes, road edges, and junctions when visibility drops. You'll find them on motorways, dual carriageways, and many A roads throughout the country.
Their name comes exactly where you'd expect – from the way a real cat's eyes glow when caught in light at night.
When Were Cat's Eyes Invented?
Cat's eyes were invented in 1933 by Percy Shaw, a British engineer from Halifax. The story goes that Shaw was driving home on a foggy night and noticed his headlights reflecting off a stray cat's eyes at the roadside. That reflection gave him the idea for a device that could guide drivers through poor visibility.
Shaw patented his design in 1934, and by 1937 cat's eyes were being installed on UK roads. His original design used glass beads, a rubber housing, and a cast iron base – simple, durable, and remarkably effective. It's a design principle that still holds today.
How Do Cat's Eyes Work?
Each cat's eye unit contains pairs of glass reflectors that face opposite directions, ensuring they reflect light back to drivers travelling in either direction. The reflectors sit inside a rubber housing that compresses when a vehicle drives over it, pushing the glass below the road surface to protect it from damage.
There's a clever self-cleaning feature built in, too. When a tyre presses the rubber casing down, rainwater collected in the base washes over the glass reflectors, keeping them clear and effective without any manual maintenance.
What Do the Different Colours of Cat's Eyes Mean?
Different coloured studs tell drivers different things about their position on the road. Knowing what each colour means is important for safe motorway driving, especially at night or in heavy rain.
White Studs
White cat's eyes separate lanes on the motorway and mark the centre of the road on standard A roads. They're the most common type you'll encounter and help prevent drivers from drifting between lanes.
Red Studs
Red studs mark the left-hand edge of the motorway, sitting between lane one and the hard shoulder. They act as a warning that you're approaching the boundary of the carriageway.
Amber Studs
Amber reflective studs sit along the right-hand edge of the motorway, marking the gap between the outside lane and the central reservation. They stop drivers from straying into the central barrier.
Green Studs
Green studs indicate junctions, slip roads, and access points. If you spot green cat's eyes, you're approaching an entry or exit point on the motorway.
Fluorescent Green or Yellow Studs
These are temporary studs used to mark changes in road layout caused by roadworks. They alert drivers to adjusted lane positions and should be followed carefully until normal markings resume.
Why Cat's Eyes Matter for Road Safety
From guiding drivers through heavy fog to preventing lane drift on a dark motorway, cat's eyes are a simple solution that saves lives. Their colour-coded system gives drivers instant information about their road position without needing to rely solely on painted line markings.
Road Marking and Road Stud Services from Northern Marking
Northern Marking has over 20 years of experience delivering professional road marking and surfacing solutions across Manchester and Northern England. We're ISO 9001:2015 quality assured, local council approved, and trusted by local authorities, private businesses, and major organisations alike. If you need work for highways or need any type of road marking, get in touch with our team for straightforward, expert advice.
