Robustness optimisation of tram timetable based on passive signal priority

Semi-exclusive right-of-way trams were considered in this research. Compared with subways, the travel time of trams fluctuates greatly due to manual driving and control by traffic signal at intersections. In this work, schedule optimisation was combined with signal timing optimisation of intersections along a tramline to improve the robustness of tram operation (i.e. the ability to resist relatively small-scale delays). On the basis of the normal needed travel time, an appropriate slack time is added to the timetable to absorb delays during tram operation. Based on historical tram trajectory data, the tram's travel time distribution at each running section/station was obtained. The PM-Band passive signal priority model was used to construct an integer programming problem to solve the slack time of timetable and signal timing at intersections. Finally, a tram robustness evaluation simulation model was established based on historical data and the robustness of the timetable was tested by adding random interference time in the tram travel process. The result shows that, compared with the traditional method, the modified timetable has great advantages in indicators such as average punctuality rate, standard deviation of the whole travel time and average delay time.