Glare and mounting height of high-beam headlamps used as daytime running lamps

Abstract

This analytical study examined the effects of mounting height on discomfort glare from reduced-power high-beam headlamps used as automotive daytime running lamps. Of interest were the effects for mounting heights between 0.864 m (34 in) and 1.372 m (54 in) - the range in which full-power low beams are currently allowed, but reduced-power high beams are not. Three analyses were performed. The first analysis involved estimating the illuminance reaching a preceding driver via rearview mirrors. The second analysis compared glare illuminance from reduced-power high beams with that from full-power low beams. The third analysis evaluated the expected changes in discomfort-glare ratings from reduced-power high beams as a function of increased mounting height. The analyses were based on photometric information from five high beams and 43 low beams from lamps manufactured for the United States market. They were performed for five following distances and three lateral offsets of the vehicles. The results indicate that allowing reduced-power high beams with mounting heights between 0.864 m and 1.372 m would not appreciably increase discomfort glare for preceding drivers as compared with (a) glare from reduced-power high beams at a mounting height of 0.864 m, or with (b) glare from currently allowed full-power low beams.