Analysis of Lighting Parameters During Adverse Weather Conditions

The most frequent adverse weather situation zones is the rain situation. Therefore the lighting properties of the traffic situation with a wet road surface are measured in great detail. The target of the investigations is to show the necessity and the potential for an improvement of headlights for this situation.

In the first part of this paper the results of experiments are shown, which analyse the visual performance of drivers during glare in wet road situations. In the second part rating experiments concerning comfortable luminance levels in front of the car during rainfall are described. To illustrate the result of these experiments the obtained rating parameters are applied to one example of a headlight beam pattern for a situation with wet road surface.