The Effects of Headlight Glare on Vehicle Detection at Dusk and Dawn

Abstract

Ten experienced drivers performed a series of closed-course tests to determine whether a target vehicle, located between other oncoming vehicles in a single-lane convoy, could be detected under various levels of ambient illumination, with its low beam headlights on and off, and with different headlight configurations on the surrounding vehicles. Levels of ambient illumination varied from approximately 0.2 to 2100 lx during the experiment. Results indicated that low beam headlights on surrounding vehicles masked the unlit target vehicle. The degree of masking depended on the level of veiling luminance emitted by the surrounding vehicles and on the level of ambient illumination. It was also found that the target vehicle was more visible under all experimental conditions when its headlights were on than when they were off. Results are discussed in relation to subject and weather variations and in terms of current lights-on laws.