Reflective studs serve to delineate your position on the carriageway, particularly in low visibility conditions such as at night or in fog. Each color corresponds to a specific location:
- Red studs mark the boundary between the hard shoulder and the carriageway.
- Amber studs denote the edge of the carriageway and the central reservation.
- White studs are positioned between lanes.
- Green studs are found between the carriageway and slip roads.
- Fluorescent green/yellow studs are used in contraflow systems and roadworks.