Reflective road studs may be used with white lines.
- White studs mark the lanes or the middle of the road.
- Red studs mark the left edge of the road.
- Amber studs mark the central reservation of a dual carriageway or motorway.
- Green studs mark the edge of the main carriageway at lay-bys and slip roads.
- Green/yellow studs indicate temporary adjustments to lane layouts, e.g. where road works are taking place.