关键词: 城市交通, 活动效用, 通勤走廊, 帕累托最优解, 韧性

Abstract: In the urban transit system, a certain cooperation relationship has been formed between the ground bus and the subway. In daily operations, as the main mode of transportation, the subway lines often bear a large amount of passenger flow, and may be affected by disturbances such as equipment failure, early termination of operations, natural disasters and deliberate attacks. It can be seen that it is necessary to further improve the scientific design of ground bus lines and enhance the resilience of commuter corridors while continuously enhancing the carrying capacity of rail transit hardware. Through the analysis of existing studies, it can be found that, on the one hand, there are few studies considering the resilience of the interaction between ground bus lines and subway lines. On the other hand, the performance of commuter corridors is also closely related to travel behavior factors. However, in the existing research on traffic resilience, the study on behavioral factors is rare.
Therefore, the research work of this paper is divided into three parts. Firstly, considering the dynamics of commuter corridor's service efficiency, variables such as travel time are introduced as the main factors to define commuter corridor's resilience, and the resilience evaluation model of the commuter corridor is established. Furthermore, the behavioral factors based on the travel activity utility are introduced into the resilience model to make it more consistent with the traffic characteristics of the commuter corridor. Finally, a feasible resilience recovery strategy will be formed through multi-objective optimization of mobile bus lines when metro stations fail.
Firstly, in the existing research, the average daily traffic flow of the bus line is often used as an important indicator to measure the resilience of the public transit network system. However, in reality, the decline in traffic flow may also be caused by a reduction in travel demand over a period of time. Therefore, considering the dynamics of commuter corridor's service efficiency, the travel time is introduced as the main factor to define the resilience of the transit commuter corridor, and the resilience evaluation model of the commuter corridor is established with reference to the definition of resilience in existing research. Secondly, based on the travel activity utility, the behavioral factors are introduced into the resilience assessment model to depict the travel behavior of ground bus and subway respectively. Moreover, the net utility of ground bus and subway is calculated respectively, which makes the travelers' perception of utility more consistent with the flow characteristics of commuter corridors. Thirdly, commuter corridor's resilience is improved by optimizing the stop plan and departure frequency of mobile bus. A multi-objective optimization model is established, in which the stop plan and departure frequency of mobile bus lines are set as variables, and the objective function is to maximize the resilience of the commuter corridor and minimize the resilience recovery cost. In the model, the travel activity utility is organically combined with the OD matrix equilibrium algorithm to depict the resilience recovery process of the commuter corridor. Moreover, the multi-objective particle swarm optimization algorithm based on quantum behavior is introduced to solve the Pareto optimal strategy of resilience recovery. Finally, the model and algorithm in this paper are applied to the commuter corridor composed of Beijing metro line 1 and the ground buses along the subway line, and the mobile bus lines in this commuter corridor are optimized based on the real traffic flow data.
The study finds the following main results. (1)When the marginal utility of travel activity is taken into consideration, the optimization model can produce the optimal solution with lower cost and better resilience improvement. (2)When the metro stations are out of service, compared with only adding the same number of inherent bus lines, the optimized bus stop plan can significantly improve the resilience of the commuter corridor. (3)Only increasing the bus departure frequency without optimizing the stop plan will not necessarily restore the resilience. In reality, the methodology proposed in this paper can provide operational decision support for traffic management departments to effectively deal with emergencies and ensure the safe and orderly operation of the commuter corridor.

Key words: urban transportation, activity utility, commuter corridor, Pareto optimal solution, resilience