A Memetic Algorithm to Optimize Bus Timetable with Unequal Time Intervals

An appropriate bus timetable is vital for bus enterprises to improve service quality and save operational cost. Most existing literature on bus timetable optimization divide a whole day into several periods and assume that departure time intervals are the same for each period. As passengers' flow varies over time in a period, giving the same time interval for each period cannot really meet the demand of passengers. In this paper, we study the optimization of bus timetable with unequal time intervals. Aiming at characteristics of this problem, a memetic algorithm is devised that combines a genetic algorithm with elite strategy and a local search. To handle infeasible solutions, a repair method is proposed to repair solutions that do not meet the constraint. A new metric reflecting the degree of bus carrying capability matching passengers' need is introduced. The metric together with passengers' waiting time is used to evaluate a bus timetable. Experiments show that compared to the actually used timetables, timetables optimized by the proposed approach are able to save about 4.54-12.84% cost and 11.87-37.76% passengers' waiting time.