Visibility research for road lighting based on a dynamic situation

Abstract

Much of visibility research related to road lighting is based on static tests with small objects. At an open-air road lighting laboratory a series of dynamic tests have been conducted. For this purpose a normal motor car was equipped with a measuring and recording set-up. The 'objects' to be detected by the drivers of this car were pedestrians. These pedestrians were not on the carriageway, but on the adjacent surroundings of the road. The results of these tests confirm the importance of the average road surface luminance. The improvement in visual performance is found to be considerable up to a lighting level of 3.4 cd/m2. Concentrating the light on the carriageway has a negative effect on visual performance as far as pedestrians positioned outside the carriageway itself are concerned: at least 40 per cent of the average illuminance on the traffic lane must be available on the adjacent surrounds.