Urban Road Network Growth Model Research

With the acceleration of urbanization,urban population growth and urban border expansion are remarkable,and the number of motor vehicles in the city is growing rapidly.This makes the city disease(such as traffic congestion,environmental deterioration,etc.)become more serious than before and inhibits the healthy development and efficient operation of a city.The urban road network is composed of all the roads in the city.It constitutes the basic skeleton of the city,and is the carrier of the social economic activities,the flow of personnel and the transportation of goods in the city.The spatial layout of urban road network is closely related to various city disease.Its rationality is conducive to promoting development of society efficiently and improving people's quality of life.Therefore,how to plan and design a scientific and rational urban road network,optimize the layout of road network,and relieve traffic pressure and environmental pressure is a challenging problem faced by researchers in the field of traffic science.The urban road network is complex and diverse,and the temporal and spatial evolution rules and mechanisms of road network are difficult to find.In view of this,this paper takes complex network theory as the basic knowledge,and uses computer simulation technology to systematically study the growth model of urban road network.The main research contents include the following aspects.Firstly,with the help of the construction mechanisms of existing urban road network growth model,two road network growth models are proposed.In Model A,a new node is generated randomly,and links are connected under the principles of length constraint,angle preference,degree constraint and relative neighbor.Model B is improved based on the Model A.In Model B,a new node is generated with the help of the competition mechanism between nodes,and links are connected under the principles of generalized length constraint,angle preference,degree constraint and relative neighborhood.The angle constraint of link connection is considered in every link connection process.Secondly,Model A and model B are used to simulate road network growth in the study area.Urban road network topology structure information of different network scales was recorded during the simulation.The simulation results of two models are compared with the previous empirical research on degree,cell area,shape factor and so on.The Model B in degree distribution,cell shape factor distribution characteristics are better than the Model A.It shows that the simulation results of Model B are closer to the actual road network structure,implying that the road network growth mechanism of Model B is closer to the actual road network growth process.Thirdly,taking the road network of Beijing as the research object,Beijing road network is empirically studied,and the parameters of the road network growth model(Model B)are calibrated.This model is used to simulate the evolution process of the Beijing road network in 1969-1978,1978-1990,1990-2000 and 2000-2008 stages of road networks.Comparing the simulation results with the actual road network data,the paper finds that the relative error of the macroscopic parameters of the road network is less than 10%.In the analysis of microscopic characteristic,the result shows that degree distribution,cell shape factor distribution and road orientation distribution are fairly close.It shows that Model B has a certain adaptability to the actual urban road network evolution.