Road stud colour carries information. A driver approaching a section of road at night reads the colour sequence before reading any sign, and the sequence tells them whether they are on a lane line, an edge line or approaching a hazard. Because of that, colour is specified by standard rather than chosen by the buyer.
The Core Convention
Across most markets, the basic division is between lane markings and edge markings. White studs mark lane divisions and the running edge of the carriageway. Amber or yellow studs mark the central reservation or the boundary of the opposing carriageway. Red studs mark a hazard side, typically the left-hand edge in left-hand-drive markets.
The logic is directional: the colour sequence on the left of the driver should always differ from the sequence on the right, so that a driver who has lost orientation can identify which side of the road they are on from colour alone.
Where Markets Diverge
| Item | Common Practice | Divergence to Check |
|---|---|---|
| Edge line studs | Red on the hazard side | Some markets use white for both edges and rely on stud spacing instead |
| Central reservation | Amber or yellow | Colour name and chromaticity limits differ between standards |
| Hazard warning | Red or flashing amber | Flashing studs are permitted in some markets only |
| Cycle lane separation | Green in several markets | Not universally adopted; check local standard |
The practical consequence for buyers is that a single colour set cannot be shipped against a multi-market order without checking each destination standard. A stud that is acceptable as a central reservation marker in one country may fall outside the chromaticity tolerance for the equivalent application in another.
Colour Fastness
Colour is specified as a chromaticity range, and that range has to hold through the service life of the stud. UV exposure fades pigments at different rates: yellow and red are more susceptible than white, and the fade is faster on the face exposed to direct sun than on the sides.
For projects in high-sunlight markets, accelerated weathering data is more useful than a colour statement on the datasheet. The relevant question is not what colour the stud is at dispatch but what colour it is after two summers.
Matching Studs to Existing Markings
Where studs are installed alongside painted lines, colour has to match the paint under both daylight and headlight. A stud that reads amber under sodium lighting and yellow under LED may conflict with a line painted to a single standard.
For retrofit projects, the simplest approach is to sample the existing markings and match the stud batch against them under the lighting actually used on that road, rather than against a colour chart.