Study on Highway Glare Index under Wet Condition Based on DIALux Simulation

Chinese road lighting norms have no limit for glare under wet conditions. The paper examines the glare phenomenon and road lighting indicators associated with glare, providing suggested indicators related to the glare and design method. The study is meaningful so that drivers can operate cars safely and comfortably under wet conditions. A simulation method that uses different kinds of surfaces to simulate reflection properties is developed. The main objects in the study are threshold index (TI) and luminance uniformity (U). DIALux, a German luminance software, was used to simulate the luminance of a two-lane road. The results show that the threshold index is ineffective under wet conditions. The luminance uniformity (U) decreases and fails to conform to the standard value. This paper suggests that the luminance uniformity (U) could be a limit value to the glare under wet conditions.