An international team of mathematicians, physicists, computer scientists and urbanists, including researchers from Queen Mary, University of London, used quantitative tools of network theory to examine the evolution of road networks, a long lasting element of urban forms considered a fundamental driver in urban development.
"Urbanization is a complex phenomenon that affects our society and shapes the environment where we live," researcher Vito Latora from Queen Mary's School of Mathematical Sciences said in a university release Thursday.
"However, a quantitative assessment of urbanization processes has been lacking."
The researchers' study of road networks around an area north of Milan called Groane suggests the evolution of such networks is driven by two key elements: exploration, when new roads trigger spatial evolution beyond the outskirts of a town, and densification, or the increase in local road density around existing urban centers.
"Exploration is more common during earlier historical periods, whereas densification predominates in later years," Latora said.
"Our study of Groane shows that over time, cells of land demarcated by roads have become more evenly distributed and square shaped.
"We found a general trend towards a greater number of four-way road junctions, compared with the earlier structure where dead ends and three-way junctions were more common," he said.
The most central streets in the network in 2007 tend to coincide with the oldest ones, showing the importance of central roads as a robust spatial backbone that remains stable over time and drives urbanization, he said.