On March 19, the Suburbia exhibition opened at the Centre de Cultura Contemporània de Barcelona. It is an exhibition dedicated to dissecting the predominant model of urban growth in the United States (and exported from there to the rest of the world) during the 20th century: dispersed urbanization, with characteristic single-family homes surrounded by a private garden and far from traditional urban centers.
This exhibition allows for many interpretations of how we inhabit the territory, and some of them I will express in subsequent articles. In this one, however, I am interested in making a brief foray into urban density, which would be the result of a model opposite to the one Suburbia portrays.
Density is, without a doubt, one of the key measures of urban planning. Some authors, such as economist Ed Glaeser, precisely define cities by the absence of space between people.
The interest in this indicator is such that tools to measure and analyze it keep appearing.
A couple of weeks before the exhibition kicked off, for example, we learned that an American researcher, Jonathan Nolan, had presented an online viewer (citydensity.com) that allows visualizing and comparing population densities between cities and metropolitan areas around the world. For each selected city, the viewer shows a line representing the average density at each point based on the distance to the city center. Logically, in general terms, density decreases as we move away from the urban center, but the pace and manner in which it does so can vary enormously between cities.
There are two fundamental differences that can be observed, for example, between most cities in the United States and European ones. The first is the absolute value of density, almost always much higher in the European case. The second is the greater or lesser homogeneity in densities, that is, whether the reduction in density as we move away from the center is progressive and regular or if it shows irregularities (indicating the existence of several dense nuclei or, in other words, urban centralities). Here, the differences even between European cities are also notable.
In the graph shown below, we observe how Barcelona, at any point from the city center to a 30-kilometer radius, which would touch Mataró, Terrassa, or Sitges, presents a higher density than other cities such as Boston (considered the "most European" of the large American cities), Manchester, or Munich. It is also observed how the line representing Barcelona is much more rugged than the others, reflecting that its metropolitan region comprises several urban centers of certain relevance.
We also have tools to take a closer look at our reality. Beyond the official indicators and maps of the Departament de Territori, data journalist Roger Tugas launched about a year ago another population density viewer, in this case in 3D and focused on the Catalan Countries, with a census section level of detail and with other variables, such as the age of the population, incorporated (data was from 2022). The previous scheme, which showed very dense central areas and progressive decrease with distance, is also very palpable here, as is the fact that today central areas tend to be the oldest.
With a few days' difference, data analyst Alasdair Rae, using Eurostat data from 2018, presented the conclusions of the study with which he wanted to determine which is the most populated, that is, most dense, square kilometer among European cities. The result: four of the top five positions correspond to Barcelona and its surroundings, which only gives up second place to a fragment of Paris. The absolute record is found in an area straddling L'Hospitalet and Barcelona itself, with 52,767 people residing in the square kilometer that delimits it. For the British analyst, for whom walking through the streets of Barcelona does not give the impression of being such a dense city, these high levels of density in the city have to do with the good quality of life attributed to it internationally and constitute a success of our urban planning.
Thus, the metropolitan region of Barcelona constitutes a global benchmark in terms of density. Despite everything, the debate on the benefits of density versus dispersion has always been open.
If we adhere to the main currents within current urbanism, generally inspired by the pioneer Jane Jacobs, we will find that denser cities and neighborhoods are considered to be those that most and best promote creativity and innovation, factors that provide economic advantage in today's knowledge-based economy. In this sense, a city that offers greater possibilities to generate formal and informal meeting spaces among diverse people is an accelerator of ideas.
It is not strange that the most famous and influential urban planner (despite not having any degree in the field) is a reference in the defense of the dense city, since precisely the peak of her activism and her production of urban theory, with The Death and Life of Great American Cities, coincides with a wave of urban renewals that threatened, particularly in early 1960s New York where she resided, the very idea of density, in line with the model shown to us by the CCCB exhibition.
From another perspective, a few years ago the research team of Carme Miralles and Xavier Delclòs (UAB) designed a JANE index of urban vitality which they applied to Barcelona in which, again following Jacobs (who even gives her name to the index), density was one of the key variables along with diversity, contact opportunities, or accessibility. According to these indices, Gràcia, Horta, or Sant Andreu would stand out for their vitality, even areas of Nous Barris, Badalona, and Santa Coloma de Gramenet, showing how this vitality does not necessarily correlate with income.
Another of the fundamental implications of having a metropolis that, as we have seen, shows several "peaks" of density at different distances from the main urban center, as a differential feature compared to other metropolises in the world, is that in Barcelona it makes much more sense to invest in a powerful proximity rail network than in the rest, since it is more feasible to locate stations that are profitable in terms of potentially user people. This is the model of metropolitan region and mobility advocated by, among others, the Metropolitan Commitment 2030, in order to take advantage of a networked metropolitan structure that few cities in the world can enjoy.
But it seems evident that excessive density also has negative consequences, as was confirmed during the period of confinement forced by the Covid-19 pandemic. In this case, people living in denser neighborhoods with a scarcity of green areas were more exposed to contagion and to experiencing the situation with more stress.
Finally, regarding the influence of density on people's health, another study, also published last year, concluded, however, that it is areas with a medium building density that present a higher risk of depression compared to high or low-density areas, regardless of individual socioeconomic factors.
It is precisely these medium-density areas that Suburbia portrays and that for quite some time have threatened the European urban model, and particularly the Mediterranean one, and its dense and diverse urban centers. It should be remembered that the metropolitan region of Barcelona doubled its urbanized area between the 70s and 90s of the last century without increasing its population and that the American model of housing developments and large shopping centers substantially transformed the metropolitan landscape.
If you want to imagine what our metropolis would be like if we continued to advance in this direction, you have time to visit this exhibition at the CCCB until September. In any case, in future articles we will try to do this same exercise.