Abstract
Based on an analysis of the conditions under which red warning triangles were used, theoretical standards were established for perceptibility and wind stability of this kind of equipment. Based on the braking distance required at a speed of 120 km /h, the minimum distance at which triangles can be recognised was found to be 210 metres. A reflective power greater than 90 cd /sg m per lux is therefore advisable for warning triangles. A statistical investigation into the number of collisions with the stationary vehicles on the road in the Netherlands is included.