Study On CVO Optimization Method And Application For Urban Transit Network

Urban transit's high efficiency in utilizing the traffic resources makes it inevitably possible to develop public transportation to abate urban traffic jam. Optimizing urban transit network is an effective method with little investment and great speed. So it has been an important research for scholars all over the world to use modern transportation planning theory and computer technology to optimize the urban transit network and maximize the benefit of the system through reasonable network layout on the basis of the existent urban road network and public transportation resource.Instead of mentioning how to implement its project by doing short-term transit optimization planning, the usual urban transit planning instituted in many cities in China has been long-term and medium-term which only functions as leading the urban transit by pointing out the transit network service level. Such is why the transit company can not use the planning to realize the project. It is not exercisable for planning department to institute many short-term planning, and the methods on optimization for transit network are complicated for transit companies. So it is very important to devise a simple and convenient method of urban transit optimization for transit companies.This paper introduces a simple new method on optimization for urban transit network——CVO method , which is realized with the transportation GIS Software TransCAD based on transit IC card database under the guidance of urban transit planning. The method firstly classifies several transit network service levels and confirms the service level that the transit network will reach by analyzing the state of nowadays transit network to get the parameter of the models. Then the method assigns transit flows on the transit network by the All-and-None transit assignment model according to the passengers'minimum cost, the result of which is analyzed to pick up the routes that are substandard. Finally, by the All-and-None traffic assignment mode, this method is used to obtain a perfect transit flows on the road network according to which the direction of the substandard routes are roughly adjusted and the operation scheme of part of the substandard routes are regulated. Several optimization projects for urban transit network can be obtained by this method, and by the transit assignment model of Stochastic User Equilibrium the best one of them will be picked up to be used through the result analysis of this model.The paper introduced CVO method detailedly about its principle, process and its operation, etc. The main studies of this research are as follows:1. A new method of transit network optimization with Chinese characters is introduced through analyzing the advantages and shortcomings of the transit network optimizations at home and abroad.2. The characters of short-term optimization are pointed out by analyzing the methods and process of transit network planning and comparing short-term and long-term transit network optimization.3. An optimization target, capable of implementing quantitative analyses of short-term optimization is introduced by analyzing optimization targets of other urban transit network optimization methods.4. All methods for obtaining bus stops OD matrix and the possibilities of establishing OD matrix based on transit IC card database are analyzed, providing data for short-term transit optimization.5. The process of CVO method is studied.6. The method is studied to make the process of the method visible by the software TransCAD based on the data of Changchun Transit planning.In order to make the CVO method precisely operational in optimizing the transit network, the paper introduced the following innovations:1. Several new methods have been introduced: the method to achieve transit planning targets by a series of short-term transit network optimization according to the classification of transit network service levels; the method for transit network optimization using several modals of transit assignment to forecast transit flows; a simple method to calculate value of time; the method for confirming weight of walking time; the method for ascertaining the congest function.2. The minimum passengers'turnover is regarded as the transit network optimization targets. A new concept is introduced——routes transit flows congruity, the maximum of which is used as the single route optimization target.3. Through analyzing the transit IC card data, the paper describes the gist to use IC card data as data for transit network optimization solving the problem that transit IC card data can not reflect the overall transit flow.4. A concept of active routs adjustment is introduced, which means the transit companies adjust the routs according to the hypothesized road network though with the road not available.The paper introduces a new method for transit network optimization replacing the complex optimization method. Under the guidance of mid-term and long-term planning, with the transit IC card data, transit companies can finish transit network optimization independently with the CVO method, thus enhancing maneuverability and practicability of transit planning.