Green reflective studs on a motorway are found where the main carriageway meets a slip road (entry or exit) and at some lay-bys or designated access points.

Main locations

  • Between motorway and slip road : Green studs mark the boundary where you join or leave the main motorway, helping you identify slip roads clearly, especially at night or in poor weather.
  • Lay-bys and some access areas: On motorways and A-roads, green studs can also indicate the start and end of certain lay-bys or access points off the main running lanes.

Why they’re used

  • They give clearer guidance at junctions and exits so drivers can position correctly and avoid last‑second lane changes.
  • Their high visibility in rain, fog, and darkness makes them a key safety aid when painted lines are harder to see.

In UK-style driving theory questions, if you are asked “Where would you find green reflective studs on a motorway?”, the expected answer is: between the motorway and its slip road (entry/exit).

Information gathered from public sources and guidance available online.