Optimization research for rescue hot standby EMU location and coverage area in a large-scale high-speed railway network

With the extension of China high-speed railway network, the number of railway stations is increasing. The challenge that railway companies are facing is how to reasonably plan the location of hot standby Electric Multiple Units (EMU) and determine the rescue coverage area of each hot standby EMU. It is uneconomical to configure a hot standby EMU for each station. Railway companies want to use the minimum number of hot standby EMUs to provide rescue tasks for the entire high-speed railway network. In this paper, we develop the optimization models for hot standby EMU location and coverage area, respectively. The models aim to maximize the rescue distance and minimize the number of hot standby EMUs. Wha'ts more, in order to reduce the complexity of the models, a method of merging railway lines is used to transform the "point-to-network" to "point-to-point" rescue problem. Two numerical examples are carried to demonstrate the effectiveness of the models. The developed models are linear, and we use Python 3.7 to call Gurobi 9.5.2 to solve the models. In the results, we can find that the developed models can provide an optimal and reasonable plan for the location and coverage area of hot standby EMUs.