Research On The Mode Of Expressway Urbanization Transformation In Economically Developed Areas

The purpose of highway planning and construction is to provide quick and convenient traffic connections between the cities with middle and long distance and shorten the passage time of vehicles.Expressways are usually built in the periphery of the city and they serve cities through the connection of the urban trunk road.However,with the development of urban economy and the expansion of urban scale,new urban groups and even planned centers have emerged in the periphery of the city.The contradiction between the expressway and the development of the city is becoming more and more prominent.The traffic volume of the expressway in the economically developed urbanized area is very huge and contains a lot of city traffic.The expressway cannot meet the demand of the traffic and it also restricts the development of the city to some extent.It is necessary to relocate the function of the expressway and carry out the urbanization transformation.This paper summarizes the methods of urbanization transformation of expressways at home and abroad and puts forward the model of three-dimensional reconstruction and expansion,and then studies the technical difficulties in the new mode and provides ideas for the follow-up research of the three-dimensional reconstruction and expansion mode.First,the paper studies the characteristics of multi-lane expressways including section composition,section form,subgrade width,capacity and so on,compares and summarizes the common methods of expressway reconstruction and expansion at home and abroad.By analyzing the problems faced by the reconstruction and expansion of expressways in the urbanization area,the paper puts forward the idea of three-dimensional reconstruction and expansion.Then the traffic demand prediction methods of expressway are summarized and analyzed,especially the "four stage method".Then we introduce the modeling process of Guangdong comprehensive traffic model and Shenzhen macro traffic model briefly and use these two models to predict the prospect traffic volume of Jihe expressway.According to the traffic volume data,the form and the scale of reconstruction and expansion are determined.Thirdly,the paper study the overall scheme and Plane-Vertical-Transect scheme of the of three-dimensional reconstruction and expansion mode.The overall scheme research includes the study of the overall layout and function positioning of the expressway,the layout of the interchanges nodes and the layout of the conversion ramps.And then the paper develops various composite modes of the layout of interchanges nodes and the conversion ramps and make a comparative study of these composite modes.The paper analyzes the characteristics of the horizontal,vertical,transverse design of the three-dimensional reconstruction and expansion mode in the urbanized area and draws up the principles of the Plane-Vertical-Transect design of the three-dimensional reconstruction and expansion mode combining the relevant regulations andrequirements of the design specification.After collecting and classifying the limiting factors along the expressway,the paper puts forward a comprehensive design method of the Plane-Vertical-Transect scheme based on the limited factors.Next,the paper studies the design indexes of the conversion ramps,including the function,design speed,section form and so on.The paper focuses on the total length,the number and position of the conversion ramps,and determines the layout,the scale and the design speed of the conversion ramps of Jihe expressway.Finally,the paper studies the selection models of expressway reconstruction and expansion.By comparing the plane expansion mode and the three-dimensional expansion mode,the paper gives the applicable ranges of these two modes.By summarizing the selection models of the plane expansion modes established by scholars at home and abroad,the paper analyzes the characteristics of these models and puts forward some suggestions for improvement.At last,the multilevel fuzzy comprehensive evaluation method(FCE)based on analytic hierarchy process(AHP)is used to establish the comprehensive evaluation model of the three-dimensional reconstruction and expansion mode,and the weight of each index in the model is calculated by using the Yaahp software.