At the 2010 Techonomy Conference, Geoffrey West gave a talk titled The Secrets of Scale (in three parts below). He offers an engaging introduction to his work on scaling phenomena in cities.
West and his colleagues examine the behavior of infrastructure and socioeconomic variables as cities grow larger. They find that some infrastructure variables, such as gasoline stations and the length of electric cables, scale sublinearly with a city’s population size. For example, rising population is associated with fewer gas stations per person and less road surface per person. Other variables, such as total employment and household water consumption tend to scale linearly with city population size.
The most interesting findings concern socioeconomic variables, many of which scale superlinearly with population. Here is West’s description from a 2009 article in SEED magazine:
"…[If] the size of a city doubles, then, on average, wages, wealth, the number of patents, and the number of educational and research institutions all increase by approximately the same degree, about 15 percent…The bigger the city, the more the average citizen owns, produces, and consumes, whether it’s goods, resources, or ideas.”
“However, the dark side of urban life manifests an analogous “superlinear” behavior. Doubling the size of a city increases wealth and innovation by about 15 percent, but it also increases the amount of crime, pollution, and disease by roughly the same amount."
The benefits of urban growth do not come without costs. Maintaining a favorable balance will require systems of rules that can adapt to the scaling effects from urban growth, enabling the benefits of urbanization (scale economies for infrastructure, higher levels of income, innovation, education, and ideas per person) while minimizing the costs (higher levels of crime, pollution, and disease per person).
Billions of people will move to cities this century, a trend that will be particularly strong in the developing world. The downsides of urbanization are not inescapable. Innovation in the space of rules can ensure that cities are cleaner, healthier, and safer places than the places urban migrants leave behind. As West suggests, developing cities that unambiguously enhance human welfare will require a deeper understanding of the social networks underlying the scale effects of urbanization.