Method for Congested Traffic Network State Analysis Based on Reasonable Routes

In order to prevent the propagation of traffic jam throughout the road network, a traffic network analysis model is built, which is based on reasonable routes taking into account both the degree of saturation and the travel time. The uncongested zone out of the central congestion layer is classified into four layers from inside to outside: control layer, guidance-and-control layer, guidance layer, and unrelated layer. These layers help reflect the spatial distribution of network traffic states and the potential evolution trend. Finally, a case study is conducted by simulation to testify the performance of the proposed model under assigned network traffic volumes. The results show that the proportion of each layer varies with the increasing traffic volume, and the congestion in congested zone tends to propagates throughout the whole network. During peak hours, the proportion of the above four layers is 20%, 5%, 10%, 10%, respectively. Within each layer, the link bearing a higher degree of saturation has a more influence on the congested zone.