Marker device for roadway, esp. for indicating an icing condition on roadway, has reflector device reacting to light from approaching vehicle

摘要

A marker device for mounting on or in a road surface (2) and which is provided with at least one reflector device (4), which reacts to light radiation emanating from a vehicle approaching on the roadway. The unit (1) changes its reflective properties depending on the temperature of the roadway.