Assessment and modelling of urban road networks using Integrated Graph of Natural Road Network (a GIS-based approach)

Road networks are one of the useful indicators through which sustainability of urban sprawl for an existing urban area and for a proposed new urban development area can be measured. Therefore, it is necessary for transportation engineers and urban planners to conduct various studies in this regard. In this paper, road networks are modelled and assessed using a method called "Integrated Graph of Natural Road Network (IGNRN)" in which the road networks are evaluated and patterned considering the importance of both nodes and road segments, simultaneously. However, the primal graph and the dual graph, by contrast, considers the importance of junctions and road segments, respectively, which are not sufficiently effective ways as far as all the aspects are concerned. For this study, a GIS-based method has been established. The method contains three major steps; 1) Data preparation 2) Modelling/Generation of IGNRN, and; 3) Measuring three classes of centrality, namely, closeness, betweenness and straightness. Finally, for validation and evaluation of methodology the case study of Kandahar City road network is carried out. The outcome of the results show that the method is accurate, helpful, and worth applying to get useful findings.