# Resilience Analysis of Traffic Network under Emergencies: A Case Study of Bus Transit Network
## 3 Methodology  
### Construction of Transportation Network Resilience Analysis Framework  
In general, bus routes and stops in a bus network are usually relatively fixed. Without changes in time and space, the entire bus network can be viewed as a static complex system. However, in reality, static conditions are difficult to achieve, and the operation of the bus network is dynamic. From a dynamic perspective, on the one hand, due to the different travel needs of passengers such as commuting, shopping, and tourism, the indicators of bus routes, such as passenger flow and operation time, are constantly changing and showing uneven temporal distribution patterns. On the other hand, due to the different travel goals of passengers, the choices of bus stops, routes, and transfer points are also different, resulting in different indicators on different routes and stops showing uneven spatial distribution patterns. From a static perspective, the routes and stops of the bus network are fixed and unchanged in the short term, and its network structure is relatively stable.  
As shown in Figure 5, in the context of studying the dynamic characteristics of bus route systems and the static structure of bus networks, this paper defines the resilience of a bus network as its ability to resist, reduce, and absorb the impact of disturbances (such as shocks, interruptions, or disasters), maintain an acceptable level of service (static resilience of the transportation network structure), and restore normal and balanced operation within a reasonable time and cost (dynamic resilience of the transportation network in terms of time and space). The performance of bus routes is the external manifestation of the working state of the network. To quantify the performance of the bus network, performance indicators must be relied upon, such as the average speed of a route, passenger flow, and one-way travel time to express route performance. To determine the most representative performance indicators, it is necessary to screen the existing monitoring indicators for bus network operation and obtain key indicators that fully reflect the status of the bus network.  
This paper first uses the CRITIC-entropy method to objectively determine the key indicators for analyzing the resilience of bus routes. Then, the changes in key indicators during the resilience cycle are taken as an expression of system performance, and a bus route resilience analysis model based on resilience cycle theory is proposed to quantify the absorption capacity, degree of performance decline, and recovery ability of bus routes in the face of unexpected events. Performance factors, absorption factors, recovery factors, steady-state recovery time factors, and fluctuation coefficients are defined for each stage of the resilience cycle, and bus route resilience is determined based on these resilience calculation factors. The resilience value of a route is a comprehensive reflection of its robustness and resistance to destruction when facing unexpected events, and the higher the resilience value of a route, the less likely it is to be affected by unexpected events. Finally, based on complex network theory, the resilience of the bus network is analyzed using the closeness centrality and edge betweenness centrality of the complex network to quantify the resilience value of the bus network in a static state. On this basis, the centrality index of the network is weighted by the resilience value of the bus route, so that the constructed model not only considers the static network structure but also takes into account the dynamics of bus routes.