IT’S THE DENSITY, STUPID!
Eduardo Cadaval
In my previous text “La iave de la ciudad” I wrote about the erroneous commitment to the so-called “urban highways” that both the Federal District and the State of Mexico governments have made in recent years. Some friends asked me if these were not a solution, what could be?
Without talking specifically about the problems of the metropolitan area of the Valley of Mexico, the answer is very simple: the mobility problems of large metropolises – different from those of medium-sized cities – are not solved either with urban highways or with circulatory devices. (roundabouts, bridges, overpasses, etc.); in fact, not even a robust public transport system alone can solve the problem. The basic solution is simply elsewhere: in the adequate balance of the population density of the different sectors of the city.
The metropolitan-scale city is after all a recent phenomenon. The dizzying speed with which cities have expanded in the last 30 or 40 years has taken the entities in charge of managing them by surprise; It was a phenomenon of such magnitude and speed that it is only now when we begin to react to adjust the excesses, mitigate the failures or plan the possible evolutions.
The growth of cities is configured through many variables, one of them is the rules that govern their expansion and organization. To think that cities are simply chaos – as some architects still love to say – is, to say the least, imprecise. Cities are complexity and complexity can be managed without cities losing their wealth. Why is New York New York? It is not just because it has different neighborhoods, tall buildings, or a specific geographic condition; It is also because it has a structure and a series of rules that promote and govern the growth and dynamics of the city. These regulations range from specific norms that articulate the density of its blocks, to strict restrictions on the construction of parking lots and the prohibition of the existence of large commercial surfaces on the ground floor. Urban wealth is not given only by spontaneous generation.
The regulation that is perhaps the most important in current urban development is that which regulates population density. What is population density? Very simple: density is the number of people who inhabit a certain sector of the city. It is calculated very simply by dividing the number of inhabitants per hectare, or by any desired unit of area. This number is commonly regulated through local laws and other mechanisms, affecting the land use plan of cities, and ends up defining the amount of square meters that can be built on a specific piece of land, the size of the minimum unit. and, therefore, the number of people who can inhabit that land and that sector of the city.
Being an extremely simple mechanism, the strategic use of population density can be a very useful urban instrument for solving many of the current problems of large metropolises. One opens the key of density and things begin to change – not without difficulties – completely.
Basically, strategically redensifying a city is to allow (and encourage) more people to live close to strategic areas of the city, both to promote its development and to amortize its equipment or infrastructures; areas where it is easier to provide citizens with the services they require. If people are brought closer to their places of work or study, and travel distances are shortened, mobility networks and public transport systems are lightened. The city becomes efficient, increasing not only its productivity but also its quality of life.
Redensifying does not necessarily mean growing in height, as Sir Leslie Martin proved many years ago in his studies at the University of Cambridge. A neighborhood can change its population density without significantly modifying its physical appearance. This has already happened in many parts of the world where urban sectors of historical value have been intervened without making major modifications to their buildings. It was enough that the norm will increase the number of inhabitants who could use or live in the old houses, and a couple of walls and some doors did the rest.
In Mexico, as in several other cities in Latin America, there are still many areas of the city that, despite having all the services and infrastructures, implausibly only allow the construction of single-family houses of the “garden city” type. We are talking about privileged areas of the city that only a few can enjoy; it is the physical exemplification of the social inequality that prevails in the country and the region.
Currently there are many people in the ZMVM who use between 4 and 6 hours of their day to move from their home to their workplace; In parallel, there are many other social-interest dwellings that have been abandoned because the times and costs of moving that living in them implied were unaffordable for their inhabitants. And on the other hand, the daily life of the city has reached unusual levels of discomfort and unproductiveness. It seems unquestionable that the time has come to begin to assimilate that there are not many other ways out other than looking for a denser and more compact city.
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