24. Automatic method for creating energy-efficient train timetables by reducing powering energy and effective use of regenerative power

There is a trade-off between improving convenience and reducing energy consumption. We have developed a method for creating train timetables that can save energy while ensuring convenience with existing train timetables. By solving a mathematical optimization problem that minimizes total powering energy consumption through adjustments in running time between each station, while keeping the total time from the starting station to the terminal unchanged for each train, a "running time adjustment timetable" is created (Figure 1, left). Next, the arrival and departure times of each train are adjusted, and a mathematical optimization problem is solved to maximize the overlap of powering and braking times between trains. This creates an "energy-efficient timetable" that effectively utilizes regenerative power (Figure 1, right). It is also possible to fix arrival and departure times at specific trains and stations in anticipation of transfers to other lines. Additionally, by incorporating restrictions on various conditions, which could not be taken into account in the past, such as speed limits and headways due to signalling facilities and other conditions, it is now possible to create reasonable energy-efficient train timetables.

To validate the effectiveness of the developed method, we conducted a case study of energy-efficient timetables using a full-day train timetable from a metropolitan area with over 400 trains, including connections of local and express services. Simulation of the created train timetable and calculation of energy consumption confirmed that vehicle powering energy consumption can be reduced and regenerative energy can be increased (Figure 2). The amount of energy supplied from substations was confirmed to be reduced by 4.4 to 7.5% (equivalent to 4.2 to 5.1 t/day in CO2 emissions) based on the existing train timetable (Figure 3).