Study On The Problem Of Combinational Vehicle Scheduling For Public Transit

With the development of social economy and high speed growth of urban population, the travel demands of urban citizen is increasingly growing, which usually exceeds the transport supply, and results in severe traffic congestion. As urban public transit has the advantages of larger carry capacity, relatively small investment and lower road occupancy rate, local governments and transport management departments have gradually realized that the key to solve the problem on urban transit is to give priority to the development of urban public transportation. The bus scheduling problem is the core content of urban public transit. Using a scientific and rational optimization management method of bus scheduling can effectively ease the contradictions of travel demands and travel supply, balance the benefits of the passengers and the bus companies, reduce passenger's travel cost and alleviate the urban traffic congestion. It also could increase the operating efficiency of public vehicles and improve the service level of public transport system.As travel demands have the characteristics of spatial and temporal unbalance for a given mass public transit line, it often leads to overcrowded for passengers in peak time and lower full-load rate for vehicles, which cause waste of limited resources. Based on the equilibrium ideal of travel demand and traffic supply, the urban combinational scheduling is a new transit operating strategy in which service vehicles operate in pairs with the lead vehicle providing an all-stop local service and the vehicle being allowed to operate only in a special zone as an short-turn service or skip some stops as an express service.Acquiring the accurate and reasonable datas of travel demand is the premise and base of bus combinational scheduling. The dissertation introduces the contents and methods of investigating passengers' datas, and then analyzes the data according to the OD demand distribution along the routes.This transit combinational scheduling concludes two types in the dissertation: short-turn vehicle combinational scheduling and express vehicle combinational scheduling. The short-turn vehicle combinational scheduling model is formulated as a non-linear programming problem with the objective of minimizing the total costs for both operators and passengers, and subjects to the full-load rate and the capacity of vehicle. The genetic algorithm is used to obtain an unbalanced timetable.The express vehicle combinational scheduling integrates express services (stop only at a few stops) with local service (stop at all stops), which is mainly used in order to reduce the waiting time of passengers in peak time. In this dissertation, the model aims at the minimum of passenger waiting time, in-vehicle time and operation vehicle trip time, and the decision variable is the different value of adjacent headway and dispatching modes. Finally, a procedure based on genetic algorithm is provided to solve the problem. A case study shows that the approach developed in this dissertation is effective and available in practice.