Research On Evaluation For City Road-network Vulnerability Based On Reliability Theory

In recent years, with the frequent occurrence of natural disasters, severe weather, majortraffic accidents and other abnormal events, it poses a great challenge on the traffic carryingcapacity and the traffic operation of city road transportation network. The structure of cityroad network is the main frame and the artery of the city operation. When a road unit in theroad network is destroyed by natural condition or artificial damage, it can make the networktraffic capacity decreased, therefore it will be a certain extent on the road network, andfurther will cause a great loss of people production and activities. In general, thetransportation network vulnerability refers to when the road network is subjected by thecertain probability but has serious consequences for failure events, it could cause the declineof the whole service level on the road network sensitivity. Therefore, the research on the cityroad network vulnerability has an important significance on the optimization of road networkstructure and the improvement of city road service level.Based on the vulnerability of the city road network which is studied by the relevantscholars, firstly, we define the road network vulnerability, namely: the road networkvulnerability refers to the result of the comprehensive function between the failure probabilityof network vulnerability unit and its consequence of the failure. On this basis, construct thecalculation model of failure probability on the road unit which is based on the reliabilitytheory, the failure probability on the road unit is comprehensive determined by the travel timereliability of the node and the connectivity reliability of the edge, it has a certain amount ofscientific nature. Secondly, depend on the road weighted connection degree, roadbetweenness and the road saturation to be as evaluation indexes to and considering the failureprobability of each road unit, integrated screen out the key sections of the city road networkin the study area unit. Finally, use the edge method to delete the key road in turn, adopt thenetwork efficiency, traffic efficiency, travel cost to evaluate the failure extent of the roadnetwork after the key section of the road unit is failure. At the same time, combined with thefailure probability of the key road unit and using the AHP method to calculate the variousindicators, ultimately get the network vulnerability strength after deleted a critical road. Therefore, it could get a scientific decision for the road network vulnerability in the regionalcity road network.This paper is based on the previous studies to define the road network vulnerability,through the network vulnerability determination method which is adopted in this paper caneffectively overcome the disadvantages of the previous method, at the same time according tothe method proposed in this paper can identify the key road and locate the structurecharacteristics of road network clearly. Accordingly, it is important to promote the planningand management of the road network and the road service ability.