Study On Urban Traffic Congestion Diffusion Based On Cascading Failure

Cascading failure is a "chain reaction".Due to the failure of a node or connection relationship between nodes in a complex network,other nodes(inter-node connection relationship)will also be affected and have a negative impact on the whole network.In the urban road traffic network,the surrounding road congestion and even the collapse of the entire urban road traffic network often occur due to the maintenance of a certain road section,natural disasters or traffic accidents,which is the phenomenon of cascading failure under the urban road traffic network.The study of cascading failure in urban road traffic network can clarify the failure propagation mechanism and identify the "key points" in the road network.On this basis,the prevention research of cascading failure can be carried out to reduce the harm degree of cascading failure.The main research work of this paper is as follows:(1)The classical ML model,CLM model and characteristics of urban road traffic network in capacity-load model are analyzed.The deficiency of ML model and CLM model in urban road traffic network is analyzed.It includes initial load determination,initial capacity determination,considering congestion characteristics,capacity updating and so on.(2)Based on the characteristics of urban road traffic network,the improvement ideas of capacity-load model are put forward,including the improvement of initial load and initial capacity determination rules,the determination of load distribution rules based on timeliness,and the construction of section capacity updating model.(3)Based on timeliness,"local urban road traffic network capacity-load model" and "macro urban road traffic network capacity-load model" are constructed.Taking the local urban road traffic network of Dalian as the research object,this paper makes an example analysis,and the importance ranking of each road section in the road network is carried out.The most important difference between "capacity-load model of local urban road traffic network" and "capacity-load model of macro urban road traffic network" is the difference of load distribution rules.The former is based on the local Angle in a short time after the road is attacked.According to the classification of adjacent sections of the attacked section,the load distribution rules are determined,and the flow of each section is determined.The latter is based on a macro perspective.Based on the clear information of the road section being attacked by travelers,OD is redistributed according to the user equilibrium flow assignment model to determine the load of each road section.