Axial lines and contour lines: climbing up the centre

The configurational approach to urban settlements seems to disregard the geometric features of their paths: in its topologic view, the morphology of streets and squares disappears so as to remain internalised within the variables which represent the configurational state of the system (Hillier, 1999). And that configurational pattern has been proved suitable to reproduce the distribution of centrality all over the settlement, with the most attractive areas (and therefore most crowded with shops and other urban activities) provided with high values of integration (Cutini, 2001a; Cutini, 2001b). All the same, when the analysis is applied to orographically strongly uneven settlements, the same functional prominence often appear to affect the steeper paths, while the level ones are frequently characterised by a poor presence of activities. An evidence like that, which furthermore seems to hardly conflict with the obvious expectations (a level path is certainly easier to go through and use than a steeper one), puts an unexpected question: is integration then depending on slope, and hence, more in general, is the grid configuration to be considered somehow influenced by the geometric (here orographic) features of the settlement? Differently, the thesis of the paper is that in such urban settlements the slope of the paths, far from being its cause, is anyhow correlated with the distribution of integration. Such an assertion is tested in several case studies (among them Arezzo, Castiglione della Pescaia, Massa Marittima, San Gimignano, Siena, Vinci), corresponding to Italian historic urban settlements which were founded and arranged on high and steep rises. And those tests provide an outstanding confirmation to the supposed correlation: as a matter of fact, slope and integration do match, and then also slope and urban centrality result to some extent well correlated. Such a correlation will then be discussed, in order to understand what is likely to influence both the slope (that’s to say the way they are disposed) and the configurational value (that’s to say the way they are mutually connected) of urban paths. Not only does integration, hence, reproduce the internal geography of an urban settlement with regard to the distribution of activities and land use, that’s to say the way that settlement is used; it also can describe (roughly but constantly and reliably) the way an urban settlement fits the specific orographic condition of its site, that’s to say the way that use is actually made possible in the local geographic context.

Il contributo, corrispondente ad un paper presentato al sesto simposio internazionale sulla Space Syntax (6th SSS), costituisce il report di una ricerca focalizzata sul rapporto fra la consistenza orografica del suolo urbano e la configurazione spaziale dei corrispondenti centri abitati. La finalità è comprendere in quale misura il fatto che tutte le tecniche di analisi configurazionale fin qui introdotte si concentrino in modo esclusivo all’assetto planimetrico della griglia urbana ne penalizzino in effetti la piena attendibilità e ne limitino le potenzialità. Il contributo reca il conforto di una esteso campionario di casi di studio, corrispondenti a centri urbani toscani caratterizzati dalla frequente presenza di percorsi scoscesi