Abstract:

By using space syntax techniques with digital historical maps in different times, this study tries to reveal the evolution process of Beijing old city's street network since the establishment of the Republic of China in the 1910s from three aspects, which are phenotype of street networks, part-whole hierarchical relation and operation efficiency. The results show that: first, the vicissitudes of dynasties divide evolution process into two parts. In the Republican Period, the street network transformed from feudal isolation structure to modern connective structure. The axisymmetric hook-ups NAIN and NACH cores patterns were broken up together. After the founding of New China in 1949, the geometry grid features of old city's street network became obvious, and the ring and big grid movement skeleton system sprang up gradually. Meanwhile, the accessibility and through frequency of different street segments became more and more similar. Second, the accessibility hierarchical relationship in each sub-area of the old city was in a constant change, however, the through frequency relationship stabilized for more than 100 years. Compared with other sub-areas, the east city had obvious spatial advantages of accessibility and through frequency. Third, two insertions of new structure and the path dependence of subsequent plan made the operation efficiency of street network experienced rise and fall. This process also emerged in east city, west city and outer city, and the stronger geometry grid feature urged east city to have a higher rising range and operation efficiency. Moreover, the imperial city's operation efficiency experienced a descent stage because of its opening wider to the outside world. In summary, this research completely organizes the phylogeny of Beijing old city's street network, provides the logical support from the street network perspective to protect the capital's traditional and inherit historical context, and expands the theoretical algorithm system of space syntax.

Key words: space syntax, Beijing old city, street networks evolution, phenotype of street networks, part-whole hierarchical relation, operation efficiency