Development of real-time optimal bus scheduling and headway control models

Infrequent bus service because of a sudden rise in international gas prices has created a significant social problem in South Korea. Bus service frequency is determined by considering bus operation costs to the service supplier, passenger demand, and so forth. Optimal bus frequency was determined and a timetable for each bus stop was created by applying the DTR (demand- and travel time-responsive) model or the DTRC (demand- and travel time-responsive model for critical scheduling areas); both use data for each bus stop and route segment. A bus headway control model that can monitor and assess punctuality of an operation was also developed. This model was based on real-time event data, such as bus stop departures and arrivals for buses operating on a line-based timetable, constructed for each bus stop. It was also based on the bus stop traffic cost, which was applied in the bus scheduling model. The model's ability to evaluate the punctuality of operation made it possible to transmit headway control instructions (when to decelerate or accelerate) to a bus driver via an onboard unit. A model verification process was implemented by using data collected from a bus management system and integrated transit fare card system for the bus route in Seoul. To evaluate the reliability and uncertainty of the optimal solution, a sensitivity analysis was implemented for the various parameters and assumptions used in the models.