Does top-down and bottom-up city morphology influence street integration?

This thesis presents an urban morphology study which examines the spatial configuration of 68 cities around the world, classified according to the circumstances under which they originated, planned or unplanned. The objective is to explain using Space syntax method, which urban morphology, top-down or bottom-up, has more influence on street integration level. An initial analysis indicates that cities belonging to the same type have similar street pattern, but at the same time they can be distinguished from one another according to the network shapes as a consequence of their different topological conditions and development. From ancient times, cities have been classified into those which grow organically and those which are planned. The distinction between these types is complex and blurred, and of course, most towns today are being formed from elements of both, bottom-up and top-down. The key difference involves the speed at which cities change, and the scale at which they develop. The differences between BU (bottom-up) and TD (top-down) cities strike at the very fundamentals of the way cities develop. Since the form of the city is in direct relation with its street network pattern, and street network pattern presents the basis for the analysis, the street integration is the main metric of this study. This study does not analyse the factors which contribute to the city shape development (street pattern shape) such as social factors, culture, land use, terrain form, climate conditions etc. This study concentrates on the pure geometry of the city, keeping in mind the difference in the way they originated: unplanned or planned. The measurement and the analysis of the spatial integration are conducted using the approach and the methods of Space syntax (Hillier, 1996). Integration is used as a measure which describes street accessibility or how easy it is to get to one street from all other streets (Hillier, 2009). Furthermore, integration explains how close each street is to all others, also known as closeness or “to-movement” (Hillier, 1996). The results obtained following this study indicate that top-down cities have higher levels of street integration compared with bottom-up cities. Significant syntactic differences appeared while analysing cities with grid street pattern, which obtained the highest level of integration overall. The most segregated results are reflected in organic-like and cul-de-sac street patterns since they consist of many dead-end streets within their network. It is also concluded that SS (Space syntax) method can efficiently quantify precise spatial configurations of the large sample, and thus, compare urban street networks from the integration point of view. By calculating integrated and segregated parts of the city, it is possible to know whether a proposed design fits into the existing structure of an area. It is also possible to create a new perspective in understanding street patterns and learn from mistakes when the integration is weak and should have been higher for the existing scenario (Hillier & Hanson, 1984). Calculating integration levels within urban areas can even help in regulating human movement, predicting crime, adapting traffic and solving commuting issues, connecting distant city centres in more efficient ways, creating social hubs or on the other hand planning safe neighbourhoods. Future study can go a step further analysing social aspects and liveability by studying human behaviour within integrated and segregated cities. The research would certainly benefit from such an effort as it would go beyond the rather clinical analysis of Space syntax and street integration level.