Synchronization of Public Transport Timetabling with Multiple Vehicle Types

Public transport (PT) timetables play an important role in creating a bridge between the PT agency, the community municipality, or both and the passengers who seek a reliable, comfortable, and attractive PT service. Inadequate inaccurate PT timetables not only confuse passengers but also reinforce the unfavorable image of PT service as a whole. Therefore, a prudent timetable strategy can improve these conditions economically and imagewise. This work addresses the problem of PT timetable synchronization while taking into consideration fluctuating passenger demand and multisize vehicle types for better matching of supply and demand. This problem was formulated as an integer programming, two-objective optimization problem. A decomposition method that integrated the route's headway, vehicle trip offset time, and vehicle type selection and assignment was developed to synchronize timetables of PT routes. The goal was to develop a maximally synchronized timetable that used a mixed-size fleet for a given PT network. The two-objective function was to minimize both the expected total passenger waiting time and the observed passenger load discrepancy at a desired occupancy level on vehicles at the maximum load points. The elaborated methodology was applied to a numerical PT network example and to a real-life PT network in Auckland, New Zealand. The results show that, compared with those of the current timetables, the total passenger waiting time and vehicle load discrepancy can be reduced by 68% to 72% and by 59% to 65%, respectively, by adopting the new timetabling strategy that synchronizes multiple types of vehicles.