"Road-Rail" Complex Passenger Transportation Network In Urban Agglomerations Vulnerability Study

Urban agglomeration transportation network is the basis for material,energy and information linkage among cities in urban agglomerations,and the construction of road network and railroad network is an important guarantee for the interconnection of urban agglomerations.In the urban agglomeration transportation system,the road and railroad passenger networks are vulnerable to disturbance events,and the network cascade failure is triggered by the process of passenger flow transfer between stations,which in turn affects the network topology and operation function,making the urban agglomeration transportation network with a certain level of network vulnerability.Therefore,it is important to investigate the vulnerability level of urban agglomerations transportation network to improve the theoretical framework of sustainable and stable development of urban agglomerations,to promote the interface between theory and practice of improving the vulnerability level of urban agglomerations transportation network,to ensure the efficient and stable operation of urban agglomerations passenger transportation network,and to facilitate the high-quality and stable development of urban agglomerations.Based on this,this paper investigated the vulnerability of "road-rail" complex passenger transportation networks in urban agglomerations.Firstly,based on the complex network theory,Space-L and Space-P methods were used to construct the road passenger transport and railroad passenger transport sub-networks of urban agglomerations respectively,and the sub-networks were connected according to the composite nodes to build the "road-rail" complex passenger transport network of urban agglomerations.Secondly,a complementary strength model was established to analyze the static and dynamic complementary strength of the "road-rail" complex passenger transportation network of urban agglomerations.The vulnerability measurement system of "road-rail" complex passenger transportation network in urban agglomerations was constructed,and the vulnerability of the network was measured from structural and functional perspectives by using network accessibility and network operational efficiency indicators.Then,we set different attack scenarios and simulate the cascading failure process and vulnerability changes of the network under different scenarios by using nonlinear load capacity model.Finally,we analyzed the vulnerability of the "road-rail" complex passenger transportation network in the Guanzhong Plain urban agglomeration by using simulation methods.The research results show that:(1)the construction of "road-rail" complex passenger transportation network in the urban agglomerations can effectively enhance the complementary roles of subsystems and improve the network accessibility and functional efficiency of the network under random and deliberate attack strategies.(2)The deliberate attack strategy based on node importance makes the network more vulnerable,and the railroad network is more resistant to disturbance than the road network in the passenger transportation sub-network.(3)Adjusting the capacity level of the nodes of the "road-rail" passenger transportation network in urban agglomerations based on the impact parameters in the load capacity model can have a significant impact on the vulnerability of the "road-rail" passenger transportation network in urban agglomerations.When the load capacity parameter α=2;β=0.1 and the capacity overload factor r=1.4,the network is more resistant to different attack strategies and the network vulnerability level is lower.(4)In the "road-rail" passenger transportation network of the urban agglomeration,the key vulnerable nodes are clustered in the large stations with dense passenger flow,and the key vulnerable areas form an agglomeration zone around the core cities of the urban agglomeration.The effective identification and protection of key fragile nodes and fragile areas is an important link to reduce the vulnerability of the network.Based on the simulation results,we propose an optimization path for the vulnerability of the complex passenger transportation network of "road-rail" in urban agglomerations,which provides a theoretical reference for reducing the vulnerability of transportation networks and promoting the construction of comprehensive transportation corridors and high-quality development of urban agglomerations.