New Classification And Route Design Index Of The Freeway Under The Urbanization Development

In the early stage of freeway construction in China,the urban development is relatively slow.The freeway designers consider the regional connectivity,but ignore the coordinated development of the freeway and the city while planning and design the freeway.With the rapid growth of transportation industry and the acceleration of urbanization process,the freeway has entered the built-up area and surrounded by the city.The freeway surrounded by the city can’t meet people’s travel demand,and it hinders the interchange between the two sides of the freeway,so it is urgent to carry out the urbanization transformation.The lack of consideration of urbanization factors in design,resulting in a lot of problems in the transformation,so it is necessary to refine the freeway research under the background of urban development.Through the analysis of urban development and expansion model,the combination forecasting method based on gray model and neural network is used to predict the development of the city in this paper,according to the function of the freeway and the location relationship with the city,this paper puts forward a new types of freeway under the background of urban development,it can be divided into three categories: general freeway,urban freeway and suburban freeway.Based on the contradiction between urban development and freeway,this paper puts forward the evaluation index system of freeway reconstruction and expansion under the background of urbanization.To facilitate the construction and reconstruction of the freeway around the city,the paper proposes the design indexes of urban freeway and suburban freeway mainly from the horizontal plan,the vertical profile and the cross section of the route,and it deals with the calculation of the median divider width,establishes the cross section lane width model and the vertical subgrade height model model.The paper makes a detailed classification of the freeway and puts forward the design index,which can reduce the inconvenience caused by the freeway entering the city and the difficulties of transformation,as well as provide guidance for the construction and reconstruction of the freeway in the future.