Space Syntax for Uncovering and Measuring the Inherent Structure of Urban Morphology
Human beings have long been attracted by the issue of how cities look like and what cities ought to be, which is indeed a question of morphology. Space Syntax is a set of approaches to analyze urban form, its formation, and its linkage to socio-economic forces through topological graph representations (Hillier and Hanson 1984). However, as complex systems, the essence of cities’ formation and construction does not lie in their superficial appearance but in their inherent structural organization. For instance,, consider Shibuya Station in Tokyo, one of the busiest transit hubs not because of its architectural design or conspicuous location, but due to its pivotal role in the city’s transportation network. This station links multiple crucial subway and rail lines, serving as a vital nexus for the urban flow, enabling efficient movement across different parts of the city for daily commutes, shopping, and socializing. More importantly, the inherent structure is factually the living structure that evokes the sense of well-being and beauty in the human heart and mind. Therefore, space syntax is both a quantitative and qualitative analysis to find the living structure by representing the topology of meaningful things in urban spaces.
Space refers to the daily space where people are living in, and the arrangement of physical spaces significantly impacts social interactions between human beings (Hillier and Hanson 1984). Traditionally, space has commonly been perceived as a mechanical construct composed of points, lines, and planes, with its qualities or goodness subjectively assessed. This space encompasses both large and small scales; large spaces cannot be fully perceived from a single point of view, whereas small-scale spaces can be comprehensively observed. However, according to Alexander, space is neither lifeless nor neutral, but a living structure capable of being more living or less living (2002-2005). From the largest of the Earth to the smallest scale of architectural details, these spaces form a continuous and coherent whole, embodying a living structure. The concept of living structure emphasizes the interconnected and complex nature of spatial arrangements, mirroring the characteristics of organic systems. The organic view of space based on living structure offers unique insights for understanding the structural and measurable nature of urban morphology.
Space syntax is to discover and measure the inherent structure of space through topological analysis. However, a space is commonly too big or too complex to be perceived entirely. In order to simplify the complexity of space in terms of adaptation for analysis, it involves two principles that one is to decompose the space into smaller scales that can be completely perceived, the other is to analyze the interactions quantitatively and morphologically between each component of space. For spatial decomposition, an axial map represents the layout of open spaces accessible and navigable within an environment. It is created by drawing the fewest and longest straight lines (axial lines) that can pass through every open space and at every junction, capturing the spatial relationships and connectivity of those spaces. It is notable that the longest axial lines should be selected for generating unique axial map and the least number of those visibility lines covering all free space.
An axial map can indeed be further transformed into a connectivity graph for an intuitive topological representation of space, offering a simplified yet insightful visualization of how different spaces within an urban environment are linked to each other. In this graph, nodes represent the axial lines or spaces, and edges signify the direct connections between them. This transformation facilitates the analysis of urban morphology through quantifiable metrics derived from the space syntax theory. Connectivity and integration are the two key metrics. Connectivity measures the direct links a space has with its neighbors, indicating potential for movement and interaction, while integration assesses a space’s depth within the overall network, reflecting its accessibility and centrality. Based on the quantitative metrics in topology, space syntax could support various applications such as transportation prediction (Ma et al. 2019). For example, the traffic flow is probably mainly centered on the streets of high connectivity and integration.
Living structure is the inherent structure of urban morphology and is precisely what space syntax aims to uncover and quantify. Defined by a mathematical structure, it is self-organized with composition of smaller inter-connected substructures and triggers the sense of wellbeing and beauty in humans. One of the key concepts in living structure is the intrinsic scaling hierarchy behind the substructures. A fundamental aspect of living structure is its intrinsic scaling hierarchy, observable through the connectivity patterns of axial lines in space syntax analysis, where there are far more less-connected axial lines than well-connected ones. Similarly, space syntax decomposes large-scale spaces into multiple small-scale spaces, resulting in far more small spaces than large spaces. This phenomenon addresses the long-tailed and non-linear dynamics inherent in the size-detail relationship within urban complexity, rendering the prediction and modeling of urban spaces a challenging endeavor.
Space syntax provides a solid approach to discovering living structure and simplifying complexity through a topological view of space. The essence of the inherent structure of urban morphology is the scaling hierarchy where there are far more small substructures than large substructures (Jiang 2020). By axial maps and connectivity graphs, space syntax enables decompose the complex spaces into simply smaller spaces that humans can easily perceived. Furthermore, based on the topological representation, the connectivity and integration of axial lines could uncover the living structure with hierarchy in a target space (Jiang 2019). Space syntax offers both qualitative and quantitative insights for the fundamental issues of cities, including how cities look like and how cities work or are organized. The generative process from a realistic urban system to an axial map is an understanding issue of urban morphology and configuration. While the opposite process from a well-organized axial map or connectivity graph into an urban planning, which is actually a design issue. The discovery of living structure makes the goodness of space an objective fact rather than a subjective opinion through topological representations and quantitative measurements by space syntax.
References:
- Alexander C. (2002–2005), The Nature of Order: An essay on the art of building and the nature of the universe, Center for Environmental Structure: Berkeley, CA.
- Hillier B. and Hanson J. (1984), The Social Logic of Space, Cambridge University Press: Cambridge.
- Jiang B. (2020), Alexander’s wholeness as the scientific foundation of sustainable urban design and planning, New Design Ideas, 3(2), 81–98.
- Jiang B. (2019), A topological representation for taking cities as a coherent whole, The Mathematics of Urban Morphology, 335–352.
- Ma D., Omer I., Osaragi T. and Jiang B. (2019), Why topology matters in predicting human activities, Environment and Planning B: Urban Analytics and City Science, 46(7), 1297–1313.