Energy-efficient Train Timetable Optimization Model for Urban Rail Transit Line with Asymmetric Passenger Demand
To relieve the asymmetric phenomenon of urban rail transit line,such as the stranding of passengers in the heavy-demand direction,the wastage of capacity and high energy consumption in the low-demand direction,this paper proposes an asymmetric transportation strategy combining skip-stop tactics and flexible train composition technology.In this strategy,more train services will be arranged in the heavy-demand direction of the transit line,and the service frequencies will be reduced in the low-demand direction.The flexible train composition technology is also utilized to improve the flexibility of capacity supply and reduce energy consumption waste.In addition,several express trains are operated in the low-demand direction to accelerate the turnover speed of rolling stocks.Based on this,an integrated optimization model of operation plan,train timetable and rolling stock circulation plan were constructed to determine the bidirectional service frequency,train composition,stopping plan,timetable and circulation plan of rolling stocks,to minimize the total passenger travel time and total traction energy cost of the entire corridor.A customized variable neighborhood search algorithm is designed to solve the mixed integer nonlinear programming model.The case study in Guangzhou Metro Line 14 showed that:compared with the actual symmetric transportation strategy,the proposed method can reduce the total passenger travel time by 6.52%,the total traction energy consumption by 34.20%,and the total objective function by 11.40%.Express trains can accelerate the turnover speed of the rolling stocks,reducing six on-line rolling stocks,which can facilitate the asymmetric strategy.Flexible train composition technology can further improve the flexibility of the capacity supply,and significantly reduce the number of on-line rolling stocks,where the average load factor of trains is increased by approximately 20%,and the optimization rate of the total traction energy consumption is increased by approximately 33%.The asymmetric strategy combined with skip-stop trains and flexible train composition can save train operating costs,and greatly improve the capacity matching degree under the asymmetric passenger demand.