Impacts of rainfall weather on urban traffic in beijing: analysis and modeling

Recently an increasing number of researches have been focused on the influence of rainfall intensity on traffic flow. Conclusions have been reached that inclement weather does have negative impacts on key traffic parameters. However, due to lack of data, limited work has been implemented in China. In this paper, the impacts of rainfall intensity on urban road traffic flow characteristics are quantified, based on the historical traffic data and weather data in Beijing, capital of China. The reductions of road capacity and operating speed are obtained by statistical estimation for different rainfall intensity categories against clear weather. Then the modified speed-density function and speed-flow function are calibrated at different rainfall levels, from which the reductions of free-flow speed can be calculated. Finally, a generalized continuous speed-flow-rainfall model is developed and calibrated. The validation results show a good accuracy, indicating the new model can be used for urban traffic management under various rainfall intensities.