Optimizing public space structure of traditional villages coupling SNA and spatial syntax

A misalignment can often be found between the spatial evolution of traditional villages and the needs of villagers under the rapid urbanization. Therefore, it is pressing on the structural characteristics of public spaces, from the perspective of material space with social demands and optimization. Current research has focused mainly on the single types or levels of public space. It is still lacking on the overall space or its users, particularly for the update and optimization of traditional village public spaces. This study aims to explore the relationship between the structural characteristics of public spaces in the traditional villages in the western Beijing region and residents' spatial use preferences. Nanjiao Village in Beijing was used as a case. Social Network Analysis (SNA) and Space Syntax were coupled to construct both an objective material space network and axial model, as well as a subjective villagers' behavioral network model. A multi-level analysis was then conducted on "village-streets-nodes" from a "point-line-plane" spatial perspective. The diagrammatic languages of SNA and Space Syntax were also integrated to visualize the structural characteristics of village public spaces, in order to explore the interaction between public space nodes and alley spaces. The results indicated: 1) The spatial form of Nanjiao Village was constrained by the mountains on both sides of the river valley, thus resulting in a band-like spatial structure with a main axis along North Street and a secondary axis along the ancient street. The central aggregation was also characterized for the peripheral dispersion and evenly distributed internal streets. Public space nodes were concentrated around North Street, the ancient street, and the historical cultural area that represented by the Niangniang Temple. A spatial network was formed to center on the village history and culture with major traffic routes as the axes. Similar settlement forms were widely distributed in the traditional valley villages with the same Niangniang Temple belief culture in western Beijing. 2) The intelligibility of Nanjiao Village was 0.44661. The density of villager behavioral network was 0.076, which was a decrease, compared with the material space network of 0.1076. The public space nodes were failed to fully utilize, indicating the lower spatial connectivity of streets and lanes and the continuity of interfaces in Nanjiao Village. Some spatial nodes were also failed to connect with the surrounding environment, which was then neglected in the villagers' daily activities. 3) The distribution of public space nodes in Nanjiao Village was centered around the main street and historical cultural facilities, indicating a factional pattern of public spaces. Simulation analysis and field research reveal that the nodes within each faction were closely connected with the strong resilience and high usage rates among villagers. The spatial network was weak outside the factions, with the ineffective connections between nodes. There were the insufficient intermediary nodes and functional facilities that weaken villagers' behavioral perception. 4) A clear tendency was found in the selection of activity venues by villagers. Specifically, public spaces were integrated organically with living spaces, indicating the high social, cultural attributes, and historical significance. More daily social activities were attracted than those along the main thoroughfare, indicating the profound influence of historical and cultural customs in western Beijing on villagers' behavioral preferences. Finally, the targeted optimization of "connection, node enhancement, and empowerment" was proposed for the precise and sustainable development of public spaces in traditional villages.