Since 2006, when the majority of the world’s population became city-dwellers (can’t use the original term “citizens” because it has now lost its connection to cities), there has been a great deal of interest in understanding these engines of economic growth. Here are some findings from Spain, in the process of being replicated in Asia.
The results reveal some fascinating patterns in city structure. For a start, every city undergoes a kind of respiration in which people converge into the center and then withdraw on a daily basis, almost like breathing. And this happens in all cities. This “suggests the existence of a single ‘urban rhythm’ common to all cities,” says Louail and co.
During the week, the number of phone users peaks at about midday and then again at about 6 p.m. During the weekend the numbers peak a little later: at 1 p.m. and 8 p.m. Interestingly, the second peak starts about an hour later in western cities, such as Sevilla and Cordoba.
The data also reveals that small cities tend to have a single center that becomes busy during the day, such as the cities of Salamanca and Vitoria.
But it also shows that the number of hotspots increases with city size; so-called polycentric cities include Spain’s largest, such as Madrid, Barcelona, and Bilboa.
That could turn out to be useful for automatically classifying cities.