"The Origins of Scaling in Cities," by L.M.A. Bettencourt in Science. Bridgeport, CT (green circle), Riverside, CA (yellow circle), and Brownsville, TX (red circle) are shown in the inset.
"The Origins of Scaling in Cities," by L.M.A. Bettencourt in Science.
Recently we have reported a number of news items suggesting that super-sized cities such as Beijing and Shanghai are taking measures to limit their population growth. This has come on the back of China‘s National Development and Reform Commission (NDRC) last year stating that more than 20 urban agglomerations around the country would be established creating huge +50million population centres.
Recent data from the State Council shows that more than 3500 new areas are identified to be constructed creating a capacity of 3.4 billion people; about 2.5 x the current population[1]. The question is being asked of who is going to live in all these new areas? The country is already world famous for the huge amount of empty housing stock and ghost cities that has been created over the past 10 years of economic boom. With growth rates long under check, the UN estimates the population will max out before the middle of the century at below 1.4 billion.
Whilst urbanisation is strongly promoted through migration to urban areas, there still appears to be a massive mismatch in terms of supply and demand. Furthermore, whilst it is well established that dense populations are more efficient in terms of wealth creation and cost-benefit, it would seem that there comes a time when a city is just too big and the economies of scale become affected by the laws of diminishing returns. Mega-cities may in fact become ever less efficient as they continue to grow.
"The Origins of Scaling in Cities," by L.M.A. Bettencourt in Science.
Back in 2013, Louis Bettencourt of the Santa Fe Institute published “The Origins of Scaling in Cities”[2] providing a clear mathematical proof that increasing the density of development is more efficient for growth, including evidence of Chinese and Asian cities. However he also pointed out that cities reach a“G” Spot where their size is optimised; increasing city size beyond that point reduces connectivity efficiency and they become destabililised, since physical and social connections become unwieldy and difficult to maintain. Below I share an overview from CITYLAB[3] putting the maths into layman’s terms.
So what is the “optimal” size for a city, especially for the intended growing cities in China? I have long advocated that China’s urbanisation should be through increasing existing small town and city size in rural areas to generate “urbanisation in-place,” encouraging localised and regional, rather than national, migration. The density of existing small and medium sized rural cities would be increased rather than creating further huge megacities with newly created ‘under connected’ development areas. Opportunity generation and social mobility, the fundamentals of migration pressure, can be alleviated without the need for huge population displacement and a plethora of cities can grow over time towards reaching their optimal ‘G’ size, rather than continually moving away from it.
