This research is the logical continuation of several previous studies concerning the relations mutually connecting the configuration of the urban grid, the movement of activities in the urban settlement, and the location of these activities. Those studies were aimed at verifying the reliability of the hypothesis on which configurational analysisis based (Hillier, Hanson, 1984, Hillier, 1996a): the role of the urban grid (appraised in configurational terms, that is to say, with regard only to the spatial relations mutually connecting all its paths) as the primary element both in the production of movement and in the location of activities. Such an assumption, if proved, should allow the prediction of the distribution of pedestrian flows and the location of urban activities on the mere basis of the configuration of the grid, making it possible to set aside the issue of the presence and position of the located activities. In the research that has been conducted so far (Cutini, 1999a; Cutini, 1999b), we have actually proved the existence of a significant correlation between configuration and pedestrian movement, while at the same specifying its limits: the correlation, very clear within limited sub-systems of the overall grid, becomes dramatically weaker if extended over the whole grid. In this study, we have taken land use into consideration, extending the analysis to the correlation between the presence of the located activities and the distribution of configurational indexes.The research has focused on the two case studies that had been previously selected and analysed; the test on a third urban case, which was chosen as a particularly significant example, provides further confirmation of the results to date. These results make it possible to prove that the methods of configurational analysis (Hillier, 1996a) provide a reliable predictive tool for determining the capacity of each part of the urban settlement to create activities and enable them to flourish; at the same time, we have also been able to pinpoint the range of reliability of these methods. In other words, the results obtained provide a new definition of the notion of urban centrality, appraised in terms of attractiveness, setting aside the actual presence and position of the located activities. Furthermore, on the basis of these results, the location of monopolistic activities emerges as a strategic variable in town planning and management.

Various hazards and endemic threats are increasingly looming over cities, leading planners to rely on a rich toolbox of flexible and inclusive planning instruments and methods, capable of dealing with unpredicted events or sudden urban contingencies, when seeking sustainable urban futures. While sustainability-oriented innovative planning approaches are gaining momentum, ways to embed connected concepts in operational planning and design decision support systems have yet to be fully developed and validated. This paper tackles this issue by proposing and testing, in a real-life scenario, a method for the computational analysis of street network resilience, based on Space Syntax theory. The method is suitable to quantify the capacity of urban grids to absorb sudden disturbances and adapt to change, and to offer support for mitigation decisions and their communication to the public. It presents a set of configurational resilience indices, whose reliability is qualitatively assessed considering the ex-ante and ex-post urban configurations generated by two exceptional and dramatic bridge crashes. These events occurred almost simultaneously in two Italian cities with peculiarly similar characteristics. The results confirm the value of the proposal and highlight urban form, and particularly its grid, as a key driver in building urban resilience, together with the self-organisation capacity of local communities.

The uncontrolled growth of urban areas worldwide is pushing a substantial part of the urban population to the fringes of society, confining them to the unsecure and unhygienic settlements that we call “informal.” These settlements lack in intelligible layout and essential services and infrastructures, thus representing a challenging issue for policy makers and urban designers in the development of renewal programs and strategies. In order to support the facing of these issues through an on-site upgrade approach, this paper argues that walkability deeply affects the functioning of informal settlements, so as to propose that they can be identified as “proximal cities,” which expresses the idea that the vital space in informal settlements has soft boundaries and follows a fuzzy logic. A quantitative analysis, based on a configurational approach, and a qualitative analysis, focused on the morphologic features of the settlements, have been implemented. A comparison of the results shows that this approach is suitable to provide a deeper knowledge on informal settlement and informal society under the assumption of their strict mutual connection. A primal definition of proximal cities, suitable for describing some properties of autopoietic urban systems, emerges from the evidence-based relationships between their spatial and social features. In this respect, a case study has been proposed and discussed.