City road networks grow like biological systems
An interesting new study has been published in the American Physical Society’s journal Physical Review Letters. The authors crunched data from some 300 cities around the world, including Delhi, looking at the physics behind urban street patterns. A short synopsis of their surprising results has been published in the New Scientist. An excerpt:
French and US physicists have shown that the road networks in cities evolve driven by a simple universal mechanism despite significant cultural and historical differences. The resulting patterns are much like the veins of a leaf.
The similarity that these road networks show is accounted for by a process that the authors describe as “local optimization” and results in networks with a consistent patterning. This suggests that top-down models of urban planning only go so far:
The study’s results might be important for understanding urban growth and “sprawl” says Barthélemy. More than half the world’s population lives in cities, a proportion that continues to increase.
“The approach could even help city planners to better predict how some street networks will evolve and to plan accordingly,” he adds.
Previous models of urban development assumed that efficient transport across the entire network motivated the system’s growth - as if planned from the top down. Focussing instead on the structure of local connections seems truer to real life, says Flammini.
Ok now everyone get over to Google Earth and see how well this works for your neighborhood…