Minimizing passenger travel time in URT system adopting skip-stop strategy

The Skip-stop is one of the known acceleration strategies in Urban Rail Transit systems “URT”. It involves assigning each train to stop at a different set of stations including the terminals, and skipping the rest. This paper solves the problem of finding the best skip-stop arrangement that minimize the average travel time of passengers. A non-linear Integer Mathematical model is formulated and is relaxed and linearized. The model incorporates 5 scenarios of arranging stations, a Safety index collision constraint; and allows for transfer and backtracking passengers. A heuristic algorithm to handle larger size problems is proposed. An Origin-Destination (OD) Matrix generator is developed to generate random test problems according to specific attributes. Twenty five test problems are generated and solved using both the relaxed model and the heuristic. Results indicate that the Math model and the Heuristic achieve 99.0% optimality for passenger's travel time. Skip-stop strategy is shown to save about 10% in travel time as compared to all-stop strategy. A 4-Factor Design of Experiments is conducted to investigate the optimality of each solution methods to different URT line characteristics. Analysis shows that optimality performance of both methods is almost insensitive to key line attributes in the tested range.