Fractal And Connection:Study On The Evolution Of Urban Street Network Morphology

The urban design philosophy has been continuously reformed since 20th Century. After the upheaval of modernist morphology, the researchers and habitant of the city started to pursue traditional street and this trend becomes more and more obvious in recent years. Along with the increasing intensity of this tendency, it is more important to establish rational cognition of the traditional street network so as to return to the tradition rationally.This Paper studies urban street network from the view of dynamic evolution. The two characters-fractal and connection of the city will be the cutting-in points of this study for the qualitative and quantitative analysis of the evolution of urban street network. In the empirical research of this Paper, two cities in four periods, namely Paris downtown area (1850-1910) and Boston old city (1895-1980), are chosen as the research samples according to the principles of historic significance, evolution and capable of evaluation. Firstly, the fractal of street network morphology reform will be compared based on dimension, branching ratio and length ratio. Secondly, the connectivity of the samples will be compared in topology connectivity and geometric connectivity. Finally, the qualitative feedback and quantitative calculation with the way of space syntax will be analyzed synthetically to evaluate the evolution of morphology, thereby to establish the connection between the reform of fractal features and connectivity during the evolution of urban street network and the quality of urban street network.The research conclusions of this Paper indicate that fractal structure and multi-connection structure have their theoretical structural advantages. In the empirical study, along with the evolution and development of the urban street network, its fractal feature has been enhanced and the connectivity and path enrichment has been improved, which is in favor of improving the integration degree and intelligibility of the street network. Thus this Paper comes up with the conclusion that the structural reform of the urban street network can be proceeded with two characters - fractal and connection, to complete its hierarchy, intensify its fractal, as well as improve its connectivity, meanwhile the connection can be distributed according to fractal principle. To sum up, the establishment of a "Vein City" according to fractal and connection characters can be used to guide the structural update and design of the current urban street network.