High density is often praised in relationship to sustainability because of the efficiencies in managing resources and benefits regarding shared transportation. Economists have also concluded that workers in denser places earn higher wages and are more productive. Studies show that doubling the density increases productivity by 6% or more. And there is an interesting 25% correlation between population density and gross metropolitan product per capita. (1) (2)
However, density is not a magic elixir. Many developing cities are struggling with overcrowding, traffic congestion, providing adequate infrastructure for water access and sanitation. In the case of Dharavi, we were looking at a slum redevelopment that would result in a population density of about 313,900 ppl/km2. The final image visualizing the massing of the proposed design, based on the 7 story’s maximum height policy, offered a terrifying view of the future – not that different from the Soviet housing projects developed during the 60s, many of which are now abandoned or soon to be demolished.
So, I wanted to explore if there is such thing as an “ideal” density. In other words, is there a correlation between the density and the perceived desirability of the city? How does it change with economical and growth differences?
If we look at the rankings of the “most livable cities” (3) and their density we can observe the following correlation:
Cities that systematically appear on the rankings of “livability” are: Zurich, Helsinki, Copenhagen, Vienna, Munich, Melbourne, Sydney, Auckland, Paris… In this study I included the 20 most acclaimed cities amongst the 3 most important rankings: Monocle, Mercer, and EIU. The average density of these 20 cities is of 3800 ppl/km2 and the deviation can be disregarded.
Although there is much debate about the criteria behind these reports, they have to do with very high ratings on safety/crime, quality of architecture, public transportation, urban design, business conditions, environmental issues and pro-active policy developments.
On the other hand, all of the cities in this list are in stable, democratic countries, have gone through a diligent constant improvement over the last, not only decades, but also centuries, and stand today with some of the highest gross metropolitan product per capita of the world. These could be thought as the most desirable cities for the top 5% of the population.
The challenge arises when addressing emerging citites such as Mumbai, Bangalore, Beijing, Shanghai, Chongqing, New Delhi or Bogota (4), with densities from 3 to 10 times higher than the “ideal” 3800ppl/km2. Slums in these cities have a key socioeconomic role, they are often used as a gate for immigrants coming from rural areas to find a temporary settlement and to eventually be able to find a job and thus enter the formal market. The precarious living conditions, sanitation deficiencies and corrupted informal economies are a source of anxiety.
If we think back on the history of some of the chosen “most livable cities,” we find a recurrent pattern of explosion of growth with subsequent stabilization. Yet the scale of these new metropolis and building capabilities are unprecedented. Even if we can greatly learn from existing urban models, new challenges will need to be addressed – for which testing and a great degree of political will be needed.
(3) http://en.wikipedia.org/wiki/World’s_most_livable_cities links to Monocle, Mercer and EIU
(4) http://www.atkearney.com/documents/10192/dfedfc4c-8a62-4162-90e5-2a3f14f0da3a Global Cities Index and Emerging Cities Outlook