# Vulnerability Analysis of the China Railway Express Network Under Emergency Scenarios
## 5 Vulnerability Analysis of CRN Under Emergency
### Policy Recommendations  
Based on the simulation study of the CRN under node failures, edge failures, and simultaneous node and edge failures induced by unforeseen events, we present a series of policy recommendations aimed at enhancing network stability. In the case of node failures, research indicates that deliberate attacks targeting nodes based on node strength have a more profound impact on the network compared to attacks based on node degree and betweenness. This is because node strength reflects a node's capacity to process and transmit cargo flow within the network. Nodes with higher strength typically perform more critical logistics functions, and their failure can lead to significant disruptions in logistics and network structure collapse. Therefore, it is advisable to prioritize the protection of nodes with higher strength in network design and emergency management. This can be achieved by establishing redundant nodes and backup paths to enhance the anti-attack capability of these crucial nodes, thereby reducing the risk of cascading failures. Additionally, implementing hierarchical protection strategies that focus on nodes with a higher degree and betweenness can effectively prevent the expansion of cascading failures, as these nodes serve essential bridging functions in the network. In addressing edge failures, it is recommended to conduct a thorough assessment of the edge's betweenness and weight. Prioritizing the protection of edges critical to the network can significantly mitigate the impact of cascading failures, ensuring the network's continued functionality. Simultaneously, it is crucial that we develop adaptable intervention strategies. Depending on the edge's position and its connections with other edges, the targeted disruption of associated edges can effectively slow the spread of cascading failures. When executing this strategy, consider the edge's location within the network and its impact on the overall network structure. For simultaneous node and edge failures, research shows that targeted attacks on influential nodes and edges can accelerate the propagation of cascading failures. However, the high connectivity and redundancy of these nodes and edges help mitigate the scope of propagation. Therefore, it is recommended that we enhance the redundancy of these highly connected nodes and edges in network design, such as by incorporating backup connections or redundant paths, to ensure network stability and recovery capabilities. Even if less influential nodes and edges are removed during an attack, the overall stability of the network can still prevent the further propagation of cascading failures. Hence, it is important that we improve the resilience of these areas to ensure rapid network recovery. When adjusting network parameters comprehensively, including the cargo flow coupling coefficient, topology coupling coefficient, and cargo flow allocation, it is evident that variations in the cargo flow coupling coefficient significantly affect the network vulnerability. The cargo flow coupling coefficient measures the strength of the coupling between adjacent nodes, indicating how the state of one node impacts its neighbors. A high cargo flow coupling coefficient increases the likelihood of cascading failures when a node fails, affecting its adjacent nodes. Thus, it is recommended that we carefully adjust the cargo flow allocation when nodes with strong coupling are compromised to delay the propagation of cascading failures. This can be achieved by modifying the proportion of cargo flow allocation, thereby improving network stability and resilience. While changes in the topology coupling coefficient have a lesser impact on network vulnerability, optimizing network topology remains an effective strategy. It is advisable to enhance the overall stability by adjusting network connections and increasing redundant connections to reduce the effects of unforeseen events. Moreover, modifying the mode of cargo flow allocation is crucial.