what colour are the reflective studs between a motorway and a slip road?

The reflective studs between a motorway and a slip road are green. These green studs indicate the presence of a slip road where vehicles may be joining or leaving the motorway, helping drivers to be aware of this change, especially in poor visibility or darkness. They serve as a warning to adjust speed and check mirrors carefully. Other stud colors used on motorways include white (lane separation), red (left edge of the road/hard shoulder), amber (central reservation), and green/yellow for temporary roadworks or layout changes.