This study is a part of the `Road and Weather conditions' project. The study was carried out in order to investigate the effects of rain on total daily traffic volume, and on driving behaviour. With respect to the daily traffic volume, no effect of rain was found. Apparently, rain does not cause a major modality shift towards road traffic. Driving behaviour in rain was found to be more cautious than in dry weather. The mean speed and the percentage of short time headways (less than 1 s) were reduced in rain. Also, the percentages of Time-To-Collisions (TTCs) less than 5 s and less than 10 s were reduced in rain. However, since safety studies reveal a higher accident rate in rain, this adaptation of driving behaviour to rain is apparently insufficient to maintain the same level of safety. (A)
Abstract