###### Abstract
Train organization alleviates the operation pressure of large passenger flow stations by optimizing supply. Adding backup trains is an effective means to cope with large passenger flow [19; 20; 21]. When the passenger flow density is high, priority can be given to adding backup trains compared to closing the entrance gate and closing the escalator facing the platform [12]. In addition to large passenger flow scenarios, the strategy of adding backup trains can also serve operation disruptive scenarios. For the period of operation recovery, while re-establishing the order of online trains, adding backup trains from storage lines or train bases can better alleviate passenger detention [22]. When the on-board signal equipment of a train breaks down, it can be considered to withdraw from operation promptly and use a backup train to \"replace\" its subsequent operation plan [7]. In addition, when a train breaks down badly and needs to be rescued, on the one hand, the faulty train should be promptly moved to the storage line or train base, and on the other hand, the strategy of adding backup trains should be used to maintain the normal service of the line as much as possible [23; 24]. Therefore, studying the use of backup trains is very meaningful. To improve accessibility, URT has shown a networked development trend, and some studies focus on the role of transfer coordination in reducing passenger transfer time. [PERSON] et al. [25] studied the optimization method of train departure time in all directions at the interchange station in a URT network. [PERSON] et al. [26] studied the transfer mechanism model and designed a model to optimize the train operation plan with the objective function of minimizing the average waiting time of transfer passengers in the interchange station. [PERSON] et al. [27] put forward the connection adjustment strategy and passenger flow assignment strategy by analyzing the influence of train delay on the connection between adjacent trains and the passenger flow composition in the interchange station. At the same time, to further utilize the operation facilities and improve the passenger experience, some URT operators have organized cross-line trains. Such trains can realize the turnover between different lines, and the according transfer passengers do not need to get off and get on, which also helps to reduce the risk of passenger detain in the interchange station. For the optimal routing and departure frequency, [PERSON] et al. [1] established an optimization model to minimize the total cost by analyzing the cross-line routing settings and their capacities. [PERSON] et al. [2] carried out the optimization of the cross-line plan and the comprehensive operation scheme of express cross-line trains by a mixed integer nonlinear programming model, which can significantly reduce the number of passenger transfers. [PERSON] et al. [3] established an optimization model for the operation plan of cross-line trains at the network level based on the principle of minimizing passenger transfer times and travel time, taking into account the constraints of line capacity, train load factor, and upper limit of routing quantity. [PERSON] and [PERSON] [4] constructed a two-level programming model for the cross-line operation of URT trains considering multiple marshaling forms, with the lower-level goals of saving passenger travel time and maximizing enterprise profits, and the upper-level goal of balancing the load factor between cross-line trains and non-cross-line trains. [PERSON] et al. [5] discussed an optimization model for train operation plans in URT networks, the model takes into account constraints such as line capacity, number of train operations, and sectional capacity, and the goal is minimizing the costs of passenger travel and enterprise operation. This paper focuses on the cooperative rescheduling of planned trains and cross-line backup trains in the large transfer passenger flow scenario.