A study on street network resilience in urban areas by urban network analysis: comparative study of old, new and middle fabrics in shiraz

Abstract

ABSTRACT Vulnerability of the urban street network in times of crisis causes problem for the evacuation, rescue, emergency services and the reconstruction process of urban areas. Despite the importance of the street network in the urban form and its effect on resilience and vulnerability of urban areas, this issue has been less addressed in researches. The study sought to comparatively examine street network resilience in three types of urban fabrics using the Urban Network Analysis. Three urban areas of Shiraz with new (regular and checkered), old (organic) and middle (semi-checkered) street network have been studied using graph theory and network analysis approach and have been ranked using VIKOR technique. Indicators studied in these areas were Reach Centrality, Gravity Centrality, Betweenness Centrality, Closeness Centrality and Straightness Centrality, and ArcMap and Rhino software have been used to measure these indicators. The Reach, Gravity and Straightness indicators are better in region 8 (historical and organic street network), but in contrast, the Betweenness and Closeness indicators in this area make network resilience difficult. Region 11 of the new urban fabric with a regular street network, especially due to the lack of two indicators “Closeness” and “Betweenness”, has the highest network resilience in times of crisis within the studied indicators and in contrast, Region 8 which has included historical urban fabric has the least street resilience. The findings indicated that despite the appropriate status of “Reach” and “Gravity” indicators in historical and organic fabrics, the network of such fabrics was harmful due to high “Closeness” and “Betweenness” indicators in times of crisis and would not have the required resilience and efficiency. Strategies to reduce the two “Closeness” and “Betweenness” indicators in the street network of historical and organic fabrics, as well as increasing “Gravity” and “Reach” in the network of new fabrics, would be effective in promoting network resilience. Highlights The resilience of different form of street network is not well studied in the literature. The resilience of urban street networks has been examined in three types of urban fabrics. Selected neighborhoods have traditional, semi-planned, and planned street network. The urban network analysis of neighborhoods was investigated using the Centrality indicators. The street networks of planned neighborhoods shows higher resilience potential.