The world's cities are absorbing one million additional people every week—and by 2030, they could consume an extra 1.5 million square kilometers of land, or roughly the area of France, Germany and Spain combined. What would be the best ways for those cities to grow? A new study examines how—before urban planners existed—a group of Italian villages evolved into suburbs outside Milan today. Such studies may eventually help planners optimize future developments.
"We know few things about how cities grow naturally," says Emanuele Strano, a doctoral candidate studying urban geography at Switzerland's École Polytechnique Fédérale de Lausanne who authored the study. "Urban planners believe that with regulations we can control the growth of cities. The question is, how can we control a thing if we don't really know how it behaves?"
The new study takes a step toward that essential understanding. Strano and his colleagues—a group of computer scientists, mathematicians, physicists and urban scholars—teamed up to provide the first quantitative analysis of how unplanned street networks evolve over time.
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