Influence of rain on motorway road capacity - A data-driven analysis

The influence of rain on motorways is proven degradative for traffic flow. This degradation can be seen from lower capacity and speed values. The effect of rain is however a highly stochastic one. Although relationships between rain intensity and capacity reduction have been offered, these show a large spread in quantitative outcomes. In this contribution a large data-driven analysis is performed for the capacity reduction effects of rain on Dutch motorways. This is performed for 11 different motorways at multiple locations per motorway and over two years resulting in 6550 capacity distribution observations. In comparison to previous research, this contribution gains strength from the large number of locations and highly accurate traffic and detected precipitation data. The analysis proves a statistically significant decrease in road capacity with increasing rain intensity and found a relationship in degradation of capacity of 1.9% per mm intensity of rainfall.