TRIP FREQUENCY SCHEDULING FOR TERMINAL QUEUING BUS ROUTES

Abstract

Many public bus transit system in cities of developing countries have to operate in a very hectic traffic environment and are often subject to a terminal queuing process: buses and crews are placed into queues at terminals after they complete a trip instead of pre-assignment to specific trips before the start of daily operation. This special feature requires the development of a specific computerised trip frequency scheduling mechanism other than conventional trip frequency determination. This paper presents trip frequency scheduling methods taking into account the terminal queuing process, the fluctuating traffic conditions throughout the day, limited bus fleet size, and lack of parking spaces. An integer programming model is developed and two heuristic methods, one of which is based on linear programming and the other a straightforward derivation from the present bus operation practice, are presented. The resulting method is tested on two selected bus routes in Bangkok and extensive comparisons are made. It appears from the study that at similar exploitation costs significantly better service can be offered to the public. The method allows the bus company to systematically plan all its bus frequencies and to allocate buses to routes in a much more efficient way than at present.