Security issues related to optimization of urban rail operating schemes under express-local mode

The operating scheme of urban rail traffic is closely related to the service level and operating costs. In particular, a study on the optimization of the operating scheme under express-slow mode is of great value. Hidden problems were revealed when an attempt was made to improve the service level. Consequently, how to promote a better service and how to solve operating safety issues are discussed in this paper. The method aims firstly at providing a better service; the entire travel time of passengers was analyzed, and a time-cost algorithm model was established, to minimize the travel time. Then, an optimized model was built and the ant colony algorithm was applied to seek the best solutions for both operators and passengers. Meanwhile, a new problem arose: there was not enough braking distance for the trains to stop in an emergency situation. Finally, the relationship between braking distance and velocity was analyzed, and we were able to assure velocity before braking. The results were that the service level under express-slow mode can be promoted through the optimized model, which also saved passengers’ time. It was found that locating the critical point of the braking distance and speed was of great importance. The study has a vital significance and can assist decisions made in support of urban rail transit operations.