The distance at which a vehicle rear marking of the 'chevron' type could be recognised on an unlit road at night has been measured. It was found that on a clear night, with correctly aimed headlights: (1) the marking was recognised at a slightly greater distance when using Anglo-American dipped headlights than when European dipped headlights were used. (2) when glare from opposing headlights was encountered there was an average reduction of about 17 per cent in recognition distance when compared with the situation when no opposing glare was present. (3) the degree of reduction in recognition distance due to opposing glare increased with the age of the observer. (4) varying the mounting height of the marking within the limits permitted by law had no effect on recognition distance. (5) a rear marking incorporating a special "high intensity" retro-reflective material was recognised at a distance approximately 20 per cent greater than was the standard rear marking, under conditions of opposing glare. When no opposing glare was present the "high-intensity" markings were recognised at a distance only slightly greater than that at which the standard markings were recognised. The recognition distances of the order of 300 metres obtained in these tests were achieved under almost ideal conditions of test and are probably in excess of those that would be achieved under normal conditions of night driving. (Author/publisher)
Samenvatting