Vulnerability Of Equilibrium Road Network Against Cascading Failure

The events such as natural disasters, large-scale activities, traffic accidents, bad weather and road construction would weaken the capacity of the road network and may cause huge loss to production and living when the road network do not have enough capacity to withstand the influence of these events. Transportation network vulnerability is the sensitivity that destructive events occurred a small probability with serious consequences result in the service level of road network decreased significantly. For a given road transport network, it is important to predict the impact of road network interruption, especially to get the most likely portion of the interruption and the severity of the impact, so can do the emergency rescue preparations and optimize the network topology, reducing the possible loss. Main contents of the dissertation include the following aspects:The connotation of transportation network vulnerability is described firstly. Base on the damage type of road network, the internal and external factors affecting road transportation network vulnerability are analyzed, and the Interpretation Structure Model for the influencing factors of road network vulnerability is built. The model analysis showed that the most fundamental factor to the road network vulnerability is the road network topology, road capacity and road network traffic flow. Then, departure from the most fundamental factors for the road network vulnerability, the residents travel behavior changes after events is considered. The vulnerability index of road network evaluate link, node and traffic area is established from travel costs, accessibility and travel demand view. In order to realistically reflect the actual vulnerability of the road network, eight different initial road network attack strategy are proposed, the load reassignment model of degenerate network is explored based on considering the cascading failure, and the road flow is obtained by the stochastic user equilibrium model.Finally, based on the vulnerability theory exploration and methodology designing, an actual road network is analyzed by vulnerability indexes. Some proposals are put forward to reduce the impact of road network vulnerability.