Research On Variable Route Bus Operation Scheduling And Mode Optimization

In the past decades, the rapid growth of car ownership and the gradually increased level of motorization have resulted in the urban traffic congestion in China. However, the level of service in public transport systems is still quite low, and the public transit cannot compete with private transport modes. The contradiction between travel demand and traffic supply becomes more and more prominent and the problems of traffic congestion and traffic carbon emission have benn more serious. Turning residents to the public transport systems is a primary way to ease urban traffic congestion, develop low-carbon transport systems and promote sustainable development of the modern cities.China has already entered a period of accelerated development of urbanization, which results in more sparse suburban and rural residential districts. The conventional fixed-route, fixed-schedule transit operation mode is not favored, and transit divisions have to spend more money in developing transit systems to reach the similar level of service in these low demand areas. Thus, devebping flexible transit services, especially the flex-route transit service, is an effective way to provide attractive transport services, ease urban traffic congestion and build low-carbon transport systems. This paper intends to study the vehicle scheduling and design optimization of flex-route transit services, and the contents mainly include:1) By analyzing the operating characteristics of flex-route systems, we propose a two-stage scheduling system, which can deal with static and dynamic travel demand in daily operation. In the first stage, the scheduling model processes the demand who makes advance notice from the system; in the second stage, the scheduling model is to handle real-time requests. This two-stage scheduling model is helpful to expand the scope of flex-route services and current scheduling procedure and shows great advantage compared with existing studies.2) We use the service quality function as the system performance measure of transit system and utilize the analytical and simulation modeling to assess the level of service under conventional fixed-route and innovative flex-route policies. A new approach is proposed to help transit planners to make better decisions between the two operating policies. This method takes into account the varying passenger demand in real-life operating environments and the critical demand density between the two operating policies has been found. When the actual demand is lower than the critical demand, flex-route policy has a system advantage compared with the fixed-route operating policy. This approach can help planners to determine the appropriate operation mode for a specific system and enhance the overall performance of flex-route systems.3) This paper proposes a novel method to formulate the fare structure in flex-route services. Different from existing studies, this method considers the level of service in different groups of passengers, which could reflect the service values provided to riders. This method provides a new idea to develop a more rational and equitable fere policy in new transit services.4) To deal with the rejected requests due to the limitation of predetermined slack time in operation, we propose a dynamic station strategy, in which rejected requests could make use of accepted curb-to-curb stops for their pick-up or drop-off The simulation results from a real-world case study indicate that the proposed strategy could effectively improve level of service when the actual demand exceeds the predetermined service capacity of deviation services, and the passenger cost function can be cut by up to 30% with the help of the dynamic station strategy. This strategy is also applicable in other kinds of flexible transit services, and could improve the operating reliability of flexible transit services.5) A new Google Maps-based scheduling system is developed for flex-route transit systems. This system relies on the powerful Google Maps and combines the road network data and traffic data. The results indicate that the developed system could work well in efficiently operating flex-route service and increase the operating reliability, which is very important for the development of flex-route systems.This paper studies the scheduling and operating mode of flex-route transit services, and optimizes the overall system design in operation. We believe that our work is helpful to promote the development of flexible transit services and improve the level of service of public transit systems, which could ease the growing urban traffic congestion.