| Road transportation network plays an increasingly important role in modern life. However, the events such as natural disasters, large-scale activities, vehicle fault, traffic accidents, bad weather, road construction and maintenance would weaken the capacity of the transportation network and may cause other road traffic congestion when the transportation network do not have enough capacity to withstand the influence of these events. It is the nature of vulnerability of road transportation network that road transportation network should fail under random factors and lose some or all of its connectivity, causing road transportation network performance or service level significantly decreased.Research on the vulnerability of road transportation networks can provide the support to determine the vulnerability degree of road transportation networks and adopt control strategies for road management department in order to prevent and mitigate the impact of destructive events. It also enhances people's prevention and response capabilities to disaster and emergency. This paper analyzes road transportation network vulnerability from the static and dynamic angle respectively, and studies the scope of influence of road transportation network vulnerability from the combining static and dynamic angles.The main research works of this paper are as follows:In Chapter 1 the paper mainly expounds the background and significance of the research on road transportation network vulnerability, and expounds the mainly research contents, the research framework and the major innovations.In Chapter 2 the paper analyzes and reviews the current research on the subject of road transportation network vulnerability. First, the concept and connotation of road transportation network vulnerability are summarized. The consensus and differences of different scholars'idea about the concept of road transportation network vulnerability are discussed and the relation and difference between the concepts of road transportation network vulnerability and reliability are analyzed. Second, the road transportation network vulnerability assessment methods are categorized and reviewed, also related concepts of road transportation network vulnerability are analyzed. Finally, the definition of road transportation network vulnerability is given.In Chapter 3 the paper analyzes the factors influencing road transportation network vulnerability. Many factors which impact road transportation network vulnerability are discussed, and the internal and external factors affecting road transportation network vulnerability are classified. The main characteristics of road transportation network vulnerability are analyzed. Then the linkages between various influencing factors are analyzed and the Interpretation Structure Model for the influencing factors of road network vulnerability is built. According to the results of the Interpretation Structure Model, the paper analyzes the most direct and fundamental factors leading to road transportation network vulnerability. Finally, the spatial difference of road transportation network vulnerability can be researched and analyzed based on GIS map overlay.In Chapter 4 the paper puts forward the comprehensive evaluation model of road transportation network vulnerability. This chapter uses the network efficiency and failure probability to describe network vulnerability from static angle, and uses road transportation network failure cost to describe network vulnerability from dynamic angle. First, the entire network is dynamicly zoning into multiple dynamic traffic zones according to the topology of the network and network flow. Second, without considering the road transportation network failure probability and traffic situation, from the operation efficiency perspective, the framework of measurement on road transportation network structural vulnerability is proposed based on the network efficiency model. Third, taking into account the probability of road transportation network failure, the model for identifying vulnerable links of road transportation network is proposed based on Bayesian Networks. This paper sets up Bayesian Networks models of identifying vulnerable links for transportation networks based on fault tree and minimal path sets. Fourth, considering the road transportation network potential traffic congestion, the cost evaluating process framework of road transport performance degradation and road disruption is given from the perspective of failure economy consequences. Road transportation network disruption performance degradation cost model is analyzed based on BPR road impedance function and user equilibrium assignment theory. Finally, the quantitative classification criterion of road transportation network vulnerability is given.In Chapter 5 the paper analyzes the influencing range of road transportation network vulnerability. First, the parameters in the cascading failure model of road transportation network are analyzed based on combination of coupled map lattices and the characteristics of transportation network. Then the law of cascading failure in road transportation network is analyzed by simulation of different transportation network topology, external disturbances and coupling strength. Finally, the failure propagation prediction algorithm of road transportation network is given.In Chapter 6 the paper gives an application example of road transportation network vulnerability assessment and puts forward some countermeasures to reduce road transportation network vulnerability. First, a specific application example is given. Second, the dynamic response process of road transportation network vulnerability is analyzed. Finally, aiming at the influence factors and characteristics of road transportation network vulnerability, some countermeasures and remedial measures are put forward to reduce the impact of road transportation network vulnerability from various points of view using network vulnerability assessment indexes and results.In Chapter 7 the paper summarizes the main research work and research conclusion as well as the future research.The main innovations of this paper are as follows: (1) The paper puts forward the Interpretation Structure Model of the influencing factors which cause road transportation network vulnerability. The paper divides the influencing factors of road transportation network vulnerability into internal factors and external factors. By means of qualitative analyses, the paper analyzes the fundamental reasons which cause road transportation network vulnerability. The hierarchical relationships between relevant factors of road transportation network vulnerability are analyzed by the Interpretation Structure Model from a qualitative point of view. The paper analyzes the most direct and fundamental factors which lead to road transportation network vulnerability.(2) The paper constructs the road transportation network vulnerability degree analysis model from three aspects, which are road transportation network operation efficiency, failure probability and economic efficiency of the failure. Without considering the road transportation network failure probability and traffic situation, from the operation efficiency perspective, road transportation network structural vulnerability is analyzed based on the network efficiency model. From the failure probability perspective, the probability vulnerability of road transportation network is analyzed based on Bayesian Networks. Considering the road network potential traffic congestion, the cost evaluation model of road transport performance degradation and road disruption is given. And the road transportation network cost vulnerability is analyzed. Finally, the quantitative classification criterion of road transportation network vulnerability is given.(3) The paper researches the law and prediction algorithm of cascading failure range of road transportation network vulnerability. The parameters in the cascading failure model of road transportation network are analyzed based on coupled map lattices. The law of cascading failure in road transportation network is analyzed by simulation of different transportation network topology, external disturbances and coupling strength. Finally, the failure propagation range of road transportation network under the external disturbance is predicted. (4) The paper analyzes the dynamic response process of road transportation network vulnerability. Several countermeasures such as optimizing the transportation network planning and design, improving the quality of roadbed and road surface conditions, properly controlling and distributing the traffic flow, predicting and forecasting the disasters, and improving the emergency warning and response ability, are put forward to reduce road transportation network vulnerability. |
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