| Studies on road networks have received intensive interdisciplinary attention because road network is a common and easily accessible spatial complex system, and it has a close relationship with human life and city evolution. Current studies cover almost every aspect of a road network including road feature extraction, road map generalization and schematization, road selection and optimization, traffic simulation and statistical analysis of road networks. However, little attention has been devoted to road network structure. This project attempts to study the properties of the structure of road networks in various aspects, i.e. scale-free, mixing patterns, small-world, hierarchy and structural fractal.;The revised Kolmogorov-Smirnov statistics and the profile of connectivity correlation probability were adopted to study scale-free property and mixing patterns of road connectivities respectively. In examination of the small-world structure, two measures, i.e., clustering coefficient and characteristic path length were introduced. In study of hierarchical structure, the ego network analysis rooted in social science was introduced and it was then improved to become weighted ego network. Finally, to examine this structural fractal property, the Maximum Excluded Mass Burning (MEMB) algorithm was employed. Traffic and other socio-economic data were collected to explore their relationships with these structural properties.;Through these studies, it has been found that (1) road networks are scale-free with an estimated exponents of power law ranged from 2.11 to 3.50; (2) shortcuts that make a road network easily accessible are created by mixing pattern in a scale-free road networks; (3) road networks are small-world with an average length of the shortest paths of eight. Results also indicate that a more developed region has a more mature road network to meet its transportation demands; (4) road networks are hierarchical in terms of the opportunities and constrains of each road in flow transmission. Ego network analysis is effective in formation of the hierarchical structure of a road network, and the weighted ego network analysis improves the performance; (5) road networks are structural fractals with fractal dimensions ranged from 2.94 to 4.90. Results indicate that the more complex the structure of the road network is, the more developed the region will be. |
