In this paper, we have provided physical explanations for the effects of rain on roadway visibility. These explanations are based on either optical or psychophysical models. We have classified the visual effects of rain into three main categories. The first category concerns light scattering by rain drops. The second category concerns splash and spray. It encompasses both rain falling on the windshield and water splashed by other vehicles. The third category concerns wet road surfaces, especially road markings, whose appearance is modified by the water layer. In the end, the reduction of visibility caused by rain and sprayed water results from a combination of these three categories of effects. We can estimate a priori that the effects of the second and third categories have the highest impact on visibility, scattering effects being negligible for common intensity downpours. To give a schematic view of these effects, we propose two diagrams.
Review of the mechanisms of visibility reduction by rain and wet road
2009
11 Seiten, 9 Bilder, 30 Quellen
Conference paper
English
Road lighting-visibility and accident reduction
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