Study On The Theory And Method Of National Freeway

With accelerated marketization, industrialization, urbanization andinternationalization, the traffic volume displays supernormal growth, and more andmore highways, especially the expressways, have confronted with the challenge ofincreasing traffic. The contradiction between growing demand for expressways andshort supply of infrastructure has become one of the major factors that haverestrained the development of highway transport. Thus, further research is highlyrequired on improvement of planning theory and method, traffic volume forecastmethod, size forecast model, layout method and layout benefit evaluation model ofthe expressway network.Based on the summarization of traditional traffic volume forecast methods, thispaper first proposes and defines the concept of national highway thoroughfare.Through analyzing the characteristics and law of current traffic distribution, theresearch on the relationship between economy and thoroughfare traffic volume indifferent areas is conducted. By tendency extrapolation method, correlation analysismethod and four-stage method, the values of parameters are calculated. Further,together with expert consultation method, this paper forecasts the future trafficdemands in national highway thoroughfares and in three key areas. These dataprovide dependable support for the design of expressway network in the next step.This paper focuses on the position and role of highway in comprehensivetransport and economic-social development and puts forward the point that is presenttime is crucial for expressway development. On this basis, comprehensive analysis isconducted on the development tendency of expressway. Considering theclassification of highway functions and hierarchical classification of highwaynetwork functions, the functions of national expressway network are determined bothin macroscopy and in microscopy, at the same time, the corresponding planningobjectives are set.Connectivity method is applied in forecasting the network size. Moreover, high,medium and low schemes are designed and analyzed. Integrating grey model andgeneralized neural network model, the GM-GRNN forecast model is built. On this basis, the size of expressway network all over the country and the size of nationalexpressway network are both forecasted. The results are compared with the one byconnectivity method.In light of the strategy option and the function localization of nationalexpressway network and the law of economic-social development, the overall layoutthoughts of national expressway network planning is explored. The method waspresented that considering hierarchical analysis as the major method and single factoranalysis as the supplementary method. The route is optimized, based on the factors ofeconomy, town planning, geography, topography, environment condition, importanceanalysis and traffic demand in major thoroughfares. Layout planning of nationalfreeway network was studied on the basis of experts’ consultation.The comprehensive evaluation method of national expressway network planningis explored through in-depth analysis of principles of evaluation index system andindex selection method of national expressway network planning. Four large groupsof index are selected. And based on that, the evaluation index system for expresswaynetwork planning is established. Introducing the mathematic approaches of AHP,Multi-objective grey correlation and DEA, the research on evaluation methods ofexpressway network planning is conducted, the mathematic model is built and theevaluation process is designed. In addition, several planning schemes of nationalexpressway network are compared and analyzed by the application of mathematicmodels.