Study On Current Status Evaluation And Reform Scheme Of Existing Urban Expressway In Chongqing

With the rapid development of national economy,the urbanization process is speeding up,and the city scale is increasing.At the same time,the urban traffic pressure is increasing.As an important node on the main skeleton of urban road network,the expressway interchange becomes the key part of urban traffic congestion and security.With more divers form,more influence factor,stricter restriction condition,and more difficult modification,the urban express route is more complicated.Therefore,it is necessity to study.Now,it is limited to study the urban expressway interchange reconstruction scheme theory and method,and most studies focused on the highway overpass,the research of urban expressway overpass improvement is very few.This paper is aimed at the characteristics of the urban expressway,from the status quo investigation,the adaptability assessment of the current situation,the design of the reconstruction plan and the method of selection and so on.The main research contents are as follows:Firstly,the research focus and investigation method of the urban expressway are studied.This paper points out the difference between the existing and the new project in the investigation and the content and the corresponding strategies.Investigation on the current situation in the urban expressway is summed up in five aspects,including interchange generalizations for the social survey,survey of traffic conditions,natural conditions,the safe operation of engineering survey and survey five categories,and it gives the specific content of each kind of investigation in detail,.This paper obtains the specific information and concrete means and methods of the survey.Secondly,this paper studies the theory and method of adaptive assessment of existing status quo.The status evaluation is put forward form the technical indexes from geometry,traffic adaptability,safety status and structure of service,and it establishes the urban expressway interchange situation assessment index system.The detailed analysis and introduction and quantification of the index is put forwarded.The comprehensive evaluation model of urban expressway is constructed based on second-level fuzzy comprehensive evaluation.The steps,methods and contents of modeling are given.Thirdly,the paper puts forward the intuitionistic method to judge the existing status quo based on evaluation model results.It can determine the overall level of the status quo of interchange,and also can judge four aspects of the situation,including the interchange in geometry technology indicators,adaptability,operation safety and traffic structure present situation of service aspect and so on.This method combined with the road network planning and other external situations to determine the main problems existing in the existing and whether to need to be reformed.The carding of the urban expressway is summarized the transformation of the four main reason interchange,and it can see clear are both the interchange need to transform into the category of which of the four big reasons or which a few kinds,convenient modification designers naturally think of take that kind of corresponding retrofit design of the retrofit scheme and concrete measures.Fourthly,the design method of urban expressway has been studied.First it summarized the design principles of both the interchange reconstruction of urban expressway,and analyzes the main factors influencing the interchange reconstruction scheme,to reform the domestic urban expressway both interchange case of carding and research,and put forward to transform urban expressway both interchange scheme in situ reconstruction scheme,and in situ expansion plan is divided into the overall plan to transform and reconstruction scheme of three shift,it analyzes the advantages and disadvantages of each scheme,and is suitable for what kind of the big four reasons.Furthermore,the detailed analysis,refinement of the four reasons and he corresponding concrete modification schemes are given.Finally it analyses the retrofit scheme comparison,then the selected evaluation index system is constructed,and finally establishing the principal component analysis is put forward based on both the interchange reconstruction scheme comparison model,so as to select the optimal scheme.Finally,Chongqing fast road interchange Yang Gong bridge is used to analysis by using the method of as mentioned from present situation investigation.The present situation assessment is analyzed,and it assessed the results.It is concluded that Yang Gong interchange bridge the existing problems and the cause of the need to transform,then the focus of the change of the subordinate reason categories are analyzed.At the same time,it compared to find the corresponding general overall reconstruction scheme and concrete retrofit scheme combined with the actual situation,and proposed the overall reconstruction scheme and concrete retrofit scheme.Finally this paper uses VISSIM to analyze Yang Gong' bridge before and after the reform,comparing the traffic operation.The results show that in the modified near future,the traffic operation of obviously improved than before,and it can meet the demand of near future.The reconstruction method was verified the rationality and validity of the scheme are obtained.