Research On Network Characteristics Of Valley-city Traffic Landscape Under The Concept Of Open Block

Urban traffic landscape,as one of the components of urban traffic,broadly includes many aspects such as road network structure,traffic flow and human behavior,which can play an important role in urban traffic evaluation.Valley-cities,as the main type of cities in western China,are characterized by zonal distribution due to the restriction of valleys,which leads to the unbalanced distribution of urban road network,low density of road network and other traffic landscape problems,which have a more severe impact on urban construction.The alleviation of the above traffic landscape problems in the concept of "open block" has been verified in western countries,which has aroused strong attention,discussion and research from all walks of life in our country.As for carry out the concept of "open block",the State Council,the Ministry of Housing and Urban-Rural Development of PRC,the China Academy of Urban Planning and Design and other relevant departments have issued and compiled documents such as "the Opinions of the Central Committee of CPC and the State Council on Further Strengthening the Management of Urban Planning and Construction" and "the Annual Report on Road Network Density in Major Chinese Cities" from 2016 to 2018.This paper aims at improving the traffic landscape of valley-cities by using the concept of "open block" for reference,and then carries out the corresponding research work.The main contents and conclusions of this paper are as follows:(1)Through summarizing the research status of traffic landscape and open blocks in valley-cities at home and abroad,the similarities and differences are analyzed between domestic and foreign related researches and the development of urban blocks.Meanwhile,the macro and micro aspects of traffic landscape network characteristics under the modern traffic landscape theory are studied by using space syntax theory and complex network theory.It is found that the existing studies do not take into account the introduction of new urban planning models,new concepts and the use of urban valley characteristics to create a complete urban traffic landscape with valley characteristics.(2)Based on the theory of space syntax,this paper takes Lanzhou as an example to analyze the syntactic characteristics of road network connectivity,average depth,overall integration and synergy.Meanwhile,according to the study of the spatial characteristics of the overall traffic landscape of the valley-city,this paper defines the selection criteria of the case blocks: When any two spatial syntactic characteristics are met to reach a lower threshold(Connect is less than 3.12,MeanDepth is greater than 19.73,GInteg is less than 0.543),it indicates that the spatial characteristics of the area are in an open state,and the area can be selected as a case block.(3)Based on the complex network theory,this paper studies two open modes: ideal gridding and reality-based gridding.By comparing the average degree,clustering coefficient,network diameter,network density and global efficiency of the two open modes,this paper summarizes the influence of different open conditions on the network characteristics of the traffic landscape of the valley-city blocks under the concept of "open block".The results show that the network characteristics of the traffic landscape of the valley-city blocks are different under different open modes.The results show that considering the moderate road opening and communication in "real conditions",the road network connectivity and traffic capacity of the inland and valley streets are obviously optimized.But the "ideal gridding" can only optimize the road network of the streets distributed along the river valley.It has practical reference value to improve the traffic landscape and enhance the traffic capacity of the streets in valley-cities.(4)Taking Lanzhou as an example,this paper discusses the existing problems of traffic landscape in valley-cities.Through model building and comparative analysis,this paper discusses on whether the "open block" concept is applicable to the valley-cities and how to "open".This paper enriches and perfects the theoretical basis of traffic landscape construction in valley-cities,and finally puts forward the future construction conception of traffic landscape in valley-cities under the concept of "open block" : "developing to small-scale building blocks,drawing the texture of valley".This conception is mainly carried out from two aspects: reconstructing traffic landscape,shaping valley texture and increasing road network density,and moderately opening blocks.