Exploring Urban Coherence through Fractality, Connectivity, and Arteriality of the Urban Street Network: Comparative Study of Five Medium-Sized Algerian Cities

Urban coherence is recognized in the literature as an essential property of a sustainable and virtuous urban form. Although remaining rather vague and dispersed, urban coherence seems to be often apprehended through the interweaving and interrelation of scales in a complex system. This exploratory work aims to deepen the notion of urban coherence by studying the street network hierarchy and connectivity in relation to an essential and identifiable property of networks, known as arteriality. It indicates the tendency of the most important streets in the network to form a continuous whole. Arteriality guarantees optimal circulation and legibility within a street network. In the first step, a literature review was conducted to identify indicators of urban coherence related to the street network. Subsequently, an evaluation of urban coherence was proposed based on three aspects: the fractality of the street network and its correspondence with a power law, the connectivity of the primary street network, and the arteriality of the street network. This conceptual framework was then tested on five cities’ street networks belonging to five medium-sized Algerian cities. The results showed that all the cities studied have a certain urban coherence due to a similar internal structuring. However, from a relative point of view, there were notable differences that can be seen when comparing the cities. It also emerged that the indicators chosen to evaluate urban coherence show a certain regularity within the same city, which may confirm their relevance.