Side effects of glare-free high beam systems – A study about self glare by retroreflection on street signs

Glare-free high beam systems relieve the driver by automatic control of the high beam and enable an increase in the duty cycle compared to manual activation. Under certain circumstances, the use of these assistance systems may lead to bright and disturbing retroreflective traffic signs. Self-glare of the driver can be the result. This article provides a concise overview of current technologies for the realization of glare-free high beam systems. Current requirements of ECE and SAE regarding maximum values, an overview of the basics of retroreflection and a look at the risks of being glared by traffic signs is presented. Discomfort glare is explored through a series of studies. As a summary, the results of a study on test persons in the laboratory which examines the discomfort glare due to bright traffic signs are introduced. The determined values for the maximum luminance for traffic signs are visualized and the results are discussed. Finally ways to avoid the drivers glare will be proposed.