saved byYule Heibel on 2008-04-28
The main influence on the simulated network as it grows is the need to efficiently connect new areas to the existing road network – a process they call "local optimisation". They say the road patterns in cities evolve thanks to similar local efforts, as people try to connect houses, businesses and other infrastructures to existing roads.
Evolution has ensured that local efficiency also drives the growth of transport networks in biology – for example, in plant leaf veins and circulatory systems.
"Cities are not just the result of rational planning – in the same way that living organisms are not simply what is in their genetic code," Barthélemy told New Scientist.
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.