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.