Assessing the Impact of Rainfall on Traffic Operation of Urban Road Network

The research reported in this paper quantifies the impact of rainfall on traffic operation of urban road network. The macroscopic analysis method of the network is the Macroscopic Fundamental Diagram (MFD), which can be used to describe and estimate the level-of-service of road network and evaluate the network-wide traffic state. Quantitative mastering the impact of rainfall on MFD of urban network is not only important for the further understanding of the MFD stability, but also important for the transportation planning and traffic management under rainy conditions. The results of the empirical analysis indicate that rainfall has an obviously diminishing effect on traffic variables of the network's MFD. The average reductions in production, accumulation and weighted speed are 0.2%, 7.8% and 5.4%, respectively. Moreover, rain has greater negative impact on network's MFD in the evening peak.