Optimizing Combinatorail Service Patterns For Urban Bus Route

With the propulsion of urbanization process and expansion of urban scope in China,urban residents living standard has been improved greatly, the trip demand has been increasing continually and people's travel distance and time are increased, which results in the increase on the demand of rapid traffic mode including cars. Consequently, traffic jams become more and more serious that leads to more and more vehicle emissions. Compared with private car, public transportation has many advantages, including less road resource occupancy, less environmental pollution per capita etc. Therefore, priority developing public transportation has been one of basic ideas for urban sustainable development.In recent years, with the construction of urban public transportation, the infrastructure of public tranportaion in many cities has been gained great progress. Urban public transportation has become the main part of urban passenger transportation system. For most of cities, urban conventional bus is the main body of urban public transportation as usual as before. Urban conventional bus has become an important way to relieve the urban traffic problems, which plays an important role in adjusting urban transport structure. How to enhace the efficiency and level of service for urban conventional bus system and attract more urban resident to ride bus, thereby, decrease motorization trip, alleviate traffic congestion and environmental pollution, is the key, to realize the flexible, effective and economical urban transit system and solve urban traffic problems with the limited resource condition .Aimed to the operation reality of existing urban conventional bus, this thesis regards the travel time as the main factor to select the trip pattern for passengers considering the transfer trip demand elasticity. The mathematical model of integrated service pattern optimization for urban bus operation has been established and the solution algorithm has been designed. The main contents of this thesis include the following:1. Based on the analysis of urban bus operation elements and servie patterns, the utility theory and logit model have been applied in the estimation of trip demand between two service patterns. Considering the passenger transfer trip demand elasticity, the estimated model for passenger to select trip pattern (express service or all-stop service or both) has been formulated, which is used to calculate the demand of each trip pattern and trip assignment on the bus service pattern.2. On basis of analyzing passenger trip cost and operation cost, a mathematical model has been proposed to optimize bus service by minimizing total cost and considering a temporally and directionally variable demand. An integrated bus service, consisting of all-stop and express services is proposed and optimized subject to directional frequency conservation, capacity, operable fleet size and acceptable passenger waiting time constraints.Since the research problem is a combinatorial optimization problem, a genetic algorithm is developed to search for the optimal result in a large solution space. The sensitivity of model parameters to some key attributes/variables is analyzed and discussed to explore further the potential of accruing additional benefits or avoiding some of the drawbacks of stop-skipping services.3. Due to the limitation of investment, many transit systems have poor operated condition and restricted bus vehicle resources. A mathematical model is developed to analyze the bus emissions by introducing the stop-skipping service into traditional all-stop service with given bus vehicle sizes and considering the bus movement along the route,which subject to the capacity constraint. It is applied to analyze that integrated bus service pattern and vehicle size impact on bus emissions.4. Considering vehicle size and bus emissions impacting on environment, the pulltants damage cost of bus eimmions has been introduced into the mathematical model. Combined with the analysis of bus travel process and bus emissions, the model is devleped to optimize bus service by minimizing the total system cost, including passenger, operator and environment costs. This study intends to offers a practical approach to design an efficient transit service and select the appropriate vehicle, frequencies and stop patterns for bus services based on different aspects of system objectives (e.g. supplier, environment or total system), which improves level of service. The result indicates that the operation efficiency and level of sevice have been enhanced, while the operation cost and the impact on environment reduced.In view of the optimization problem on integrated bus service patterns, this thesis analyse the passenger transfer trip demand elasticity base on utility theory. The mathematic models have been formulated by differernt aspects of system to optimize the frequencies and stop patterns of integrated service patterns and also consider the vehicle size. The genetic algorithm has been applied to search the optimal solution. The bus eimmisions has been considered into the bus travel process. Finally, the models have been applied to a general bus route in-reality in Chengdu city, in order to verify the model validity. This study can provide theoretic foundation for bus agency to choose the appropriate operation service strategy for bus route.