Risk And Safety Assessment Of Urban Rail Transit Networks Operation

ABSTRACT:With the rapid development of urban rail transit, some megacities'urban rail transits move into networks operation era, the networks scale expand and the passenger flows increase with each passing day. Compared with conventional single-line operations, the characteristics of networks operation mainly reflect in the obvious contradiction between passengers and capacity, the strong correlation between the stations. The local problems'linkage effect on the whole networks are more prominent, and the risk increases. The paper aims to propose a set of risk and safety assessment theory and method for urban rail transit networks operation. The research contents are as follows:(1) Taking the network's holistic behavior risk and safety as research objectives; and on the basis of system engineering theory, the risk analysis and safety assessment framework of urban rail transit networks operation is proposed;(2) On the basis of network topology, and centering on the system function and passengers, the dynamic and weighted network model and transportation model of ubran rail transist are eatablished; based on above, the risks of urban rail transit networks operation are analyzed from four aspects: heterogeneity (topology, transport capacity and passengers), vulnerability (topology, transport capacity and passengers), connectivity and passenger flows distribution.(3) Based on above, the identification method of critical stations and interval in networks is proposed to provide decision support for the operation management and monitoring; and the dynamic comprehensive safety assessment model of urban rail transit network operation based on Topsis and Gray correlation analysis is established.The feasibility and rationality of the methods described above are verified through the Beijing urban rail transit. The results show that:under existing network topology, the risks of urban rail transit network operation change dynamically:one the one hand, the more trains plan, the bigger the passengers are, and the more heterogeneous the distribution of micro-properties are, once the stations and intervals fail, the greater the influence on the network function is, the more vulnerable the network is, and the greater the risk is; on the other hand, the more unbalanced the passengers distribution is, the lower the whole network connectivity is. Additionally, the risk indicators interact each other; the change of any indicator will affect other indicators, which result in the increase of network operation risk. The safety state of Beijing urban rail transit network is lower in morning and evening peak than other periods, and is lowest in morning peak.The studies prove the above method can make up for the shortcomings of existing risk analysis and safety assessment of urban rail transit operation, find the weak links and risk control point in whole networks, achieve the change from'single-line management'to'holistic-network management', and provide the theory and method for improving the ability of risk control and safety.