The motorway stud colours are a common topic in the driving theory test. These studs are also known as cat’s eyes, as they are a similar shape to cat’s eyes and reflect in the night. They are designed to help drivers see where the different sections of the motorway are. The four parts of the motorway that are marked with coloured studs are: The slip road, the hard shoulder, the lanes and the central reservation.
The coloured studs are made of plastic and are also used on dual carriageways and roads with poor lighting because they are reflective, meaning that they reflect your car headlights back to you, allowing you to see them in the dark.

The Motorway Stud Colours

Green motorway studs mark where the slip road meets the motorway. They are shown both for when the road is joining in to the motorway traffic and leaving it.
Red motorway studs are used to show where the hard shoulder of the motorway is. The hard shoulder is on the far left of the motorway and is used when pulling over during an emergency.

White motorway studs are placed between the lanes of the motorway. They help drivers to see where the lanes separate and make sure that they remain in their lane.

Amber motorway studs mark the far right of your side of the motorway, i.e. the central reservation. This is what separates you and the oncoming traffic.

The image below shows a good visual representation of the motorway road stud colours. As you can see, it goes from green / red on the left for the slip road / hard shoulder, white in the middle of the lanes, and amber on the far right for the central reservation.

Here is a quick reference for you to memorise the stud colours more easily:

Green = Slip road
Red = Hard shoulder
White = Lanes
Yellow = Central reservation

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