Railway vertical alignment optimisation at stations to minimise energy

As the energy prices and environmental concerns increasing, improving railway operation efficiency, which is an effective method to reduce energy consumption and operation expense, attracts people attention. In metro systems, the two traditional approaches to minimise energy consumption are optimising the timetable and driving strategy, respectively. In this paper, a new approach is proposed to improve energy efficiency by optimising the vertical alignment at stations along metro route. Firstly, we develop a simplified route with one station in the middle to analyse the relationship between energy consumption and the parameters of vertical alignment at the station. Secondly, we carry out an optimisation simulation on vertical alignment at Beijing Subway Yizhuang Line No.5 station. The results show that the energy consumption could be reduced by 1.66%. Finally, the optimisation simulations are extended to the entire Yizhuang Line. The results show that with adding optimal vertical alignments at all stations, the total energy consumption and journey time could be reduced by 5.6% and 0.53%, respectively. Above all, optimisation of the vertical alignment at stations is an effective way to minimise energy consumption and improve energy efficiency.