Urban Transportation Network Layout Planning Model And Application Of Urban Agglomeration Core City Based On Complex Network Theory

The scientific and rational core city external transportation planning is the"traction" and "booster" of urban group transportation planning and development.However,as the construction of urban clusters with new forms of urban development,the time spent in China is not long,the urban agglomerations theoretical research on transportation,especially the core city's external transportation planning,is still in its infancy,and the methods and results with practical guidance are still very limited.At present,the external transportation planning of core cities usually adopts the "four-stage"method of traditional urban transportation planning.However,in the context of urban agglomerations,the core cities' external traffic,regardless of traffic demand characteristics,or multi-modal and multi-level traffic composition,is significantly different from traditional urban traffic.Therefore,in theory and practice,people have been actively exploring and reflecting the core cities.Traffic planning method for traffic characteristics.This paper takes Nanning,the core city of the Beibu Gulf urban agglomeration,as the research object.In analyzing the difference between single core and multi-core structure of urban agglomeration,the external traffic demand reflects the economic attraction intensity.The external traffic network covers high-speed railway and general speed railway.On the basis of complex network characteristics such as multiple modes and multiple levels of expressways,explore the use of complex network theory to analyze the shortcomings of existing traffic lines,clarify the planning direction,build a network and establish a two-tier planning model,and provide external traffic for the core cities of urban agglomerations.Planning provides actionable theories and methods.The main research contents of the thesis are as follows:(1)Analysis of the relationship between external transportation and urban agglomeration development in core cities,It clarifies the position of the core city in the urban agglomeration,compares the external traffic of the city in the traditional sense with the external traffic of the core city,and points out that the characteristics of the external traffic of the core city of the urban agglomeration are hierarchical,and the external traffic network is determined.The main modes of transportation are highways,high-speed railways and general-speed railways.(2)The application of the traditional "four-stage" planning method at the urban agglomeration level mainly includes the forecast of the total passenger and freight demand during the external transportation planning period of the core city,the forecast of the volume of each direction,and the distribution of passenger and freight demand in each direction.In order to ensure the accuracy of the results,different forecasting models are applied according to the characteristics of passenger and freight traffic flow,and finally the scheme of traffic volume changes in different directions of external traffic in each target year of the core cities of the urban agglomeration is obtained.(3)Establish a network topology structure for the external traffic network of the core city,evaluate the existing external traffic network based on the evaluation index of node degree,clustering coefficient and shortest distance based on complex network theory,and analyze the current core city.The problems existing in the traffic network propose reasonable solutions for different problems,form a set of planned routes that need to optimize the external traffic line network,and provide alternative line sets for the construction of the subsequent two-layer planning model.(4)Establish a two-level planning model for the existing line and the planned line set.The upper layer model has the lowest generalized cost,including the cost of the new line and the travel cost due to the traffic flow change caused by the new line;the lower layer model is the traffic flow within the channel.A randomly distributed model that represents the individual's travel behavior within the channel.The hybrid particle swarm genetic algorithm is used to solve the model,and the route construction schemes in different directions of different target years are obtained.Through the research on the location and function of the external traffic of the core city of the urban agglomeration,the demand forecast of the external traffic,the analysis of the characteristics of the network and the solution of the model,the basic framework of the external traffic network design of the core city of the urban agglomeration is constructed.I hope this article can be the Chinese urban agglomeration.Provide a certain reference to the development of external transportation in core cities.