Glare Causes in Nighttime Traffic - How can we minimize the risk of glaring headlights to increase traffic safety?

Glare is generally described as a visual condition in which one feels uncomfortable or visual performance is reduced due to unsuitable lighting conditions. Drivers especially encounter the issue of glare in nighttime traffic. Besides the uncomfortable feeling for the driver the reduction of visual performance due to glare can affect safety. Therefore, regulations regarding photometric limits and the continuous development of adaptive front lighting systems aim to minimize the risk of glare in nighttime traffic. However, since glare events still occur, it is necessary to continue the investigation of glare issues. Here the question arises whether the basic conditions, such as photometric limits and headlight system design, are decisive, or whether circumstances that can change during the operational life of a vehicle (headlight adjustment, soil contamination, etc.) are mainly responsible for increasing the glare risk. Therefore, the aim of this paper is to identify glare causes that occur during the product life cycle of a vehicle. These causes should then be assigned to the different phases in the product life cycle (production, operation) and evaluated according to their relevance. The findings of the research should be used to address contributors (OEMs, suppliers, legislation, society) to the respective causes of glare, who can play a decisive role in remedying or at least improving the current situation. It is crucial to draw the attention of all parties involved to the glare issue in order to have the chance to reduce glare for all road users and improve safety in nighttime traffic.