The reflective studs between a motorway and a slip road are green in color. These green studs indicate the presence of a slip road where vehicles may be joining or leaving the motorway, helping drivers to identify these junctions, especially in low visibility or dark conditions. This color coding is part of the UK motorway stud system where each color has a specific meaning for road safety and navigation. Other colors and their meanings are: white studs for lane separation, red studs for the left edge of the motorway, and amber studs for the central reservation or right-hand edge of the motorway. Green studs specifically mark the separation between the main carriageway and slip roads to alert drivers about traffic joining or exiting the motorway.