White road studs mark lanes or the middle of the road. What is their use?

• A. Mark the left edge of the road.
• B. Show the edge of the road.
• C. Indicate a central reservation.
• D. Mark lanes or middle of the road.

Answer: (D)

White road studs are there to define the road layout by marking where the lanes are and where the middle of the road sits. They reflect light, so in poor visibility—at night, in rain or fog—you can still see the lane boundaries and keep to your lane, helping you avoid drifting across the central line. They specifically indicate lanes or the centre, rather than the road edges, which are shown by other color markers.