Study On The Theories And Comprehensive Assessment Method Of The City Of Short Distance

Since the beginning of the 20^th century,the urbanization process continues to accelerate throughout the world.However in recent years,urban growth usually happens in contradictory ways to the concept of sustainable development and eco-city, so-called urban sprawl.Spatially diffused and functionally segregated urban structures tend to cause such urbanization problems as drastic growth in traffic volumes and increased pressures on the environment.Car-oriented mobility has become the major character of the urban life style,and transport is the biggest urban problem.The theory of City of Short Distance(CSD) believes that the causes for modern urban development problems arise from the false development view of the decision-makers and the improper values and life style of the habitants.Isolated measures to promote transport planning are insufficient for the solution of the complex urban problems.Scientific mode of urban development can be achieved by cooperating and optimizing the urban structures and functions,popularizing sustainable mobility and steering the people behavior.CSD is an eco-city and sustainability oriented mode of urban development.Besides the research background(chapter 2) and the conclusion(chapter 8),this dissertation mainly consists of three sectors.The first sector(chapter 3,4 and 5) interprets the concept and theory of CSD.The second sector(chapter 6) develops the comprehensive assessment method of CSD.The third sector(chapter 7) analysis the cases studies of CSD theories.In the first sector,by reviewing the literatures on urban development at home and abroad,this dissertation briefs the classic and contemporary theories concerning CSD,summarizes the contributions and representative conclusions of various theories and schools,and illustrates the theoretical foundation of the CSD theory as well.The CSD theory is a supply-oriented mode of urban development,including the meso- and the local scales.The meso-scle,namely in the region,it signifies a network or a linear structure of polycentric urban pattern surrounded by the nature.The local scale,namely in the urban quarter & neighborhood,it contains three key elements, namely compact structure,mixed use and landscape.Ecological limits,succession, diversity,co-evolution,dominant species,law of the minimum,native spices are some important ecological connotations in the CSD theory.This theory is an Eco-city oriented mode of urban development and one of the approaches to realize the Eco-city ideal.CSD is the heritage of the New Urbanism and will be development of it.It is a more integrated and comprehensive urban development mode than other relative theories such as "Car-free City" and "Low Energy City".The research objectives of CSD focus on the urban quarter and neighborhood in spatial dimension;while nature green area,brownfield and infill development are the three major site categories.To study CSD as a complex system,research object of urban development is divided into five sub-systems for the analysis of the regularities of each sub-system's development and their interrelationship.These sub-systems are urban context sub-system,reflecting the background and foundation of the developing area;and urban structure,transport,energy & material,socio-economy sub-systems,reflecting the detailed content of urban development.In respect of the temporal dimension of urban evolution,CSD theory focuses on the whole life cycle of urban development, other than isolated stages of planning and design.Public participation,assessment and supervision are effective throughout the whole process.Comprehensive assessment on CSD involves two incorporating phases:ex post evaluation and ex ante evaluation.Moreover,the dissertation proposes the overall goals of CSD development on the core principles of "minimization of harms to the environment and human health" and "maximization of human welfare and community feelings",which includes 15 items in five sub-systems.While the CSD connotations of 25 items based on the philosophy of "short distance" and "qualified density" are carried out as well.The CSD mode emphasizes the guidance of the theory on the practice of urban development.Its actualization is guaranteed by the scientific and comprehensive assessment methods.In the second sector,firstly by reviewing the researches on urban development at home and abroad,this dissertation constructs a framework of the indicator system of CSD according to the classification of five sub-systems.15 key indicators are screened out through principal component analysis,forming the assessment indicators for ex post evaluation.Furthermore,key indicators and additional indicators constitute the constructive indicators for ex ante evaluation.Secondly,by applying the sensitivity model based on bio-cybernetics,the criteria matrix is built to evaluate the integrity of the indicator system structure according to the correlation between the 15 key indicators and 18 bio-cybernetic system criteria.The impact matrix is composed to identify the system role of the key indictors according to their mutual influences.The evaluating results are important references for decision-making procedure.Finally,this dissertation formulates the classified comprehensive assessment index of the CSD indicator system.In view of the third-level key indicators,also known as the assessment indicator system,fuzzy logic and standardized function are used to standardize the value of these indicators in advance.With the diagram of indicator rose,the comprehensive assessment index for the whole evaluating system and each key indicator can be calculated respectively.In view of the second-level indicator themes(sub-systems),also known as the constructive indicator system, weights of the indicators are calculated by the Delphi-AHP method and each theme index is worked out through weight average of its inferior indicators in advance.With the diagram of indicator tree,the comprehensive assessment index for the whole evaluating system and each theme can be calculated respectively.In the third sector,to demonstrate the feasibility and desirability of the CSD theory for its future application to urban development and construction,seven specific sites are selected for cases studies by the project of Ecocity:Urban Development towards Appropriate Structures and Sustainable Transport,through which the CSD theory is primarily formed and put forward.These involved research areas are of different spatial dimensions,situated in various European countries with diverse socio-economic backgrounds,distinct climate zones and geographic conditions. Focusing on two major cases accomplished by the author,this dissertation further illuminates the connotation of the CSD theory with the support of practical research results.Besides,the comprehensive assessment method is applied on three research areas to assess the differences between the original status and the outcome after implementing the CSD mode.Finally,this dissertation studies the application of the CSD mode in China's urbanization process in three aspects:the feasibility and necessity analysis;the inspiration and experiences of object design,planning procedure regulation,transport system development and comprehensive assessment;problems and potential obstacles caused by the Chinese specific characteristics and the lack of practical researches.