Analysis of on-time performance of bus services using simulation

Applications of a microcomputer-based Monte Carlo simulation model for analyzing the impact of different operating strategies (e.g., additional time points, bus priority, and demand profile) on two measures of quality of service of fixed-route bus services are discussed. Two fundamental service quality measures, i.e., headway variations and the degree of adherence to schedules (on-time performance), are considered. It is shown that simulation can provide the necessary insight needed for planning bus-service operations when journey speeds, passenger demand, and route characteristics are uncertain. For instance, it is demonstrated that when the interstop journey speed of a route is normally distributed, the deterioration in on-time performance with respect to dispatch time is a direct function of the variance of the distribution. There is also certain limit to the number of time points that can have a positive influence on headway variations and on-time performance. This paper describes the use of the simulation model for identifying the optimal number of time points and for assigning them to the route to achieve the desired on-time performance level.