The Design Theory And Methodology Of Flexible Microcirculation Transit System Oriented On The Transfer Station

In the context of urbanization and motorization, the contradiction between supply and demand of urban transport is becoming increasingly acute, which has become a real, unavoidable and urgent issue in the urban development process in China. Given the reality and existing problems, prioritization of public transport has become one of the important strategies that are in line with the urban and transport development. So far, some cities in China have made great achievements in urban transport development; however, the share of public transport in urban travel is still low. As for the reasons, besides the unbalance between the service supply and demand, a more important one is the slow progress of integrated public transport system and slow development of the new transit system given the existing supply of public transport services. Consequently, an existing transit service in a city can hardly be connected with a new one in an effective manner and thereby, causing many common problems to urban public transport, resulting in poor service quality with negative implication to the city’s economy and people’s travel options.So, this paper presents a new design theory and approach of a flexible microcirculation transit system that is adaptable to the reality and implementation environment to address the travel difficultly in an area that is not covered by feeder transit service, where disaggregated passenger flow is generated (at for example low density catchment of ridership or low demand time period) or service demand of special users exists to satisfy personalized and flexible demand. This study aims to create effective connection among all kinds of transit systems to improve the accessibility of the urban transit system, improve the efficiency of urban transit and facilitate the development of an integrated urban transit system.Firstly, the connotation, function and characteristics of flexible microcirculation transit system are defined from analysis on the mechanism. The key design parameters and acquisition method are stated, and the planning and designing process of the new system is presented.Secondly, the analysis and findings of willingness survey of this new system are presented for purpose of decision-making and research is carried out on the catchment of interest in terms of users’acceptance to the new service, key parameters of their concern and fare affordability. Some critical issues are also discussed and similar surveys of other countries are referred to for comparative analysis.Thirdly, domestic road network and conditions, home-based travelers’ behaviors and transit planning as well as operational practice are reviewed in terms of network rationalization and an optimal service catchment choice model is developed based on a basic network of "irregular service catchment and disaggregated demand" within an area of the largest possible service attraction radius, which is oriented toward the transfer hubs that are themselves not connected into the network, a reality existing in most cities in China. This model abandons the international modeling assumption of "a rectangular service catchment and uniform demand distribution", and develops a model that maximizes the served passenger demands while minimizes the service operation cost to provide decision-making support. Numerical studies have demonstrated the effectiveness of the proposed model and algorithm.Finally, for purpose of system operation, with respect to the special needs and operating characteristics of a flexible microcirculation transit system that provides service to the transfer hub, an operation model with "coordinated scheduling of buses running on extended catchment" is presented based on a circular service area for given service demand and vehicle fleet size. Considering the two sides of interests, that of the traveler (minimized waiting time for a feeder bus and minimized transfer time to a main line of transit service) and that of the operator (minimized operation time), a model for route planning and coordinated scheduling is developed to concurrently optimize the transit route planning and service scheduling. In the end, a new gravity model with a heuristic algorithm is presented, which is verified by means of numerical cases for validity and effectiveness.The major innovative contribution of this dissertation is summarized as follows. The flexible microcirculation transit system is discussed and analyzed in depth regarding the system characteristics and the main factors and procedure to be considered for the system planning and designing is proposed; and subsequently with respect to the reality of domestic "community-turf kind of characteristics of housing development that is supported by irregular road network and undeveloped branch local street network, a network-based optimal service area choice model based on "irregular service area and disaggregated demand", a routing optimization and service coordinated scheduling model, and an operation model with "coordinated scheduling of buses running on extended catchment" are developed, based on which a research frame is constituted for the planning, design, operation and management of the new system. To better deal with the reality, the coordinated service scheduling model proposed in this dissertation warrants further research for modeling extension and expansion. Besides, development of an effective service operation and management system is among other research topics, an important subject for research programs in the future.