Abstract:

With the rapid development of urbanization in China and the formation of urban agglomeration scale， the problem of urban traffic congestion brought about by the increase in the number of motor vehicles is becoming more and more serious year by year. A large body of literature suggests that road traffic congestion is the main cause of increased carbon emissions and high air pollution in cities. Therefore， to achieve the "double carbon" goal， it is not only necessary to give play to the energy saving and pollution reduction effect of the transportation industry， but also to pay attention to the treatment of alleviating traffic congestion.In order to alleviate urban road traffic congestion， first of all， from the theoretical level， the local static congestion caused by the assumption of “homogeneity” of bus lines is described as the mismatch between supply and demand in economics， and on the basis of the assumption of “heterogeneity” of bus routes， the hub and spoke network design is introduced into the optimization problem of urban bus routes. Secondly， the article takes the survey data related to residents' bus travel in Tongzhou District as a sample， verifies that the travel distance of residents coincides with the simulated electronic cloud and the distribution of two-order Weibull， and incorporates factors such as travel time value， safety factor， and comfort factor into the total cost function required by residents to take public transportation， so as to construct the advantageous travel distance function of residents taking different levels of bus lines as a standard. Finally， the demand for buses at different levels is defined as the product of the average travel distance of the corresponding bus lines and their traffic volume， and the supply of bus lines at different levels is defined as the product of the total traffic volume of the bus system and the proportion of passengers of the bus lines at this level， and on this basis， an hub and spoke multi-level bus line configuration model is constructed to test the mismatch between the bus travel needs of residents in Tongzhou District and the transportation capacity provided by the urban bus system.The results of the study show that the bus demand for the axis and auxiliary lines in Tongzhou District is much greater than the bus supply of the corresponding grade lines， and there is a mismatch between supply and demand； the demand for branch buses is smaller than the bus supply of this level， and there is a mismatch between oversupply and demand. The corresponding countermeasures are propased for the above problems， dynamically the mismatch is adjusted between supply and demand of different levels of bus lines， resources are reconfigured， a balance is achieved between supply and demand， and the local static congestion problem of urban public transportation is alleviated， in order to provide a scientific theoretical basis for the transportation sector to promote the realization of carbon neutrality goals， reduce pollution and reduce emissions， and alleviate traffic congestion.

Key words: multi-level bus line optimization, hub and spoke network, traffic congestion mitigation, supply and demand balance, resource allocation