Reframing Density and Ecology

Author: Antonia Burchard-Levine

Urban spaces reveal the intricate relationship between human activity and biophysical processes. Exploring the condition of Mexico City through the lens of urban congestion exposes the entangled layers of history and current urbanization trends, and the confrontation between urban infrastructure and ecological systems.

Expert input from:

  • Ninotshka Matute, Architect & Executive Director of Fundación CRECER - Guatemala City

  • Christopher Zegras, Professor of Transportation and Urban Planning in the Dept. of Urban Studies and Planning at MIT

When the ancient Maya civilization of the Yucatan peninsula witnessed the slow deterioration of their environment, they thought they had angered their gods. In the hopes of reviving their ecosystem, they diverted their resources and labor towards building more and larger temples, hoping that their gods would absolve them. As they carried on, unknowing that it was a maladaptive strategy to revert the stresses they were experiencing, they only worsened their plight and spiraled into an eventual collapse of their environment and civilization.

The fate of the Maya provides a cautionary tale to the thriving metropolis that emerged from Tenochtitilan, capital of the neighboring and subsequent Aztec civilization, known today as Mexico City.

Kilometer-long vehicular bottlenecks, crammed buses, and overcrowded underground transportation systems have become intrinsic to the experience of commuting in modern-day Mexico City. With 34.5 million daily trips, Mexico City ranks amongst the most congested cities in the world. Commuters tend to spend 52 percent longer in traffic, and will lose about eight days and three hours a year stuck in traffic. This situation will only be aggravated, as projections estimate that there will be 6.5 million vehicles roaming in the city by 2030. In parallel, with over 5.5 million daily users, and sometimes six people per square meter during peak hours, Mexico City’s underground metro system is the second most congested metro system in the world, just behind New Delhi.

These levels of congestion not only showcase the hardships that millions of daily commuters have to suffer every day, but also result in economic losses. The high levels of emissions stemming from these patterns of mobility are an ever greater concern for the environment. At the national level, negative externalities associated with transportation cost Mexico between 2.9 percent and 4.9 percent of GDP, and contribute almost a quarter of CO2 emissions (of energy consumption) and 80 percent of air pollution in Mexican cities.

The term “congestion” often derives negative associations, revealing thoughts of traffic bottlenecks and overcrowding, and sometimes even with disease and ailments. Yet congestion, or more appropriately density, brings about a plethora of positive elements to an urban setting.

Mexico City is outgrowing its carrying capacity, and this cannot be made more clear than through the fact that the city is sinking at a yearly rate of thirty centimeters.

An exploration of congestion in modern Mexico City exposes the complex and intricate interactions of its historical layers, of decades of chaotic urban expansion, and ultimately reveals the incongruent growth between its urban infrastructure and its ecological landscape.



The Metropolitan Area of Mexico City (ZMVM) is one of the largest and most populated urban agglomerations in the world. With just over 20 million inhabitants, it spans an area more than 5000 km2, roughly equivalent to five times the size of the Greater London region. Yet it proliferated at a rate of which its foundation was never prepared to assimilate.

In 1325, the Aztecs settled on an island at 2,240 meters above sea level in the middle of a lake formed within an ancient volcanic crater, and founded their capital, Tenochtitlán. Surrounded by lakes and mountains, the Aztecs ingeniously built a sophisticated civilization on a lakebed, while taking advantage of its natural setting which offered strategic military and economic advantages, as well as abundant resources for their sustenance.

By the sixteenth century, the Spanish Conquest brought about the aspirations of a growing empire requiring more space, land, and resources. Surrounding lakes were drained and covered, forests were cleared, and wells were dug deep into the aquifers to bring water to quench the needs of a growing metropolis. Today, Tenochtitlán has morphed into modern-day Mexico City. With layers of asphalt and concrete poured onto it and a constant inflow of inhabitants, Mexico City is one of the largest urban agglomerations in the world. The demands of a contemporary capitalist society, global supply chains, urban lifestyles, and consumption patterns exponentially aggravate demands on the already fragile ecosystem on which Mexico City was founded. As it will continue to grow, it will only require more resources, and further room to grow.



Urban sprawl is often the combined result of population growth, outmigration towards the periphery, but also of failed coordination, lack of planning, and a number of market distortions. As Ninotshka Matute, architect and executive director of Fundación CRECER, explains, a city expands in part due to growing demand for housing and land, as developers acquire inexpensive land on the peripheries. Yet these low-cost lands are far removed from urban infrastructure and isolated from all the productive central areas of the cities. As a result, more people have to commute, prompting higher demands for motorized vehicles and road infrastructure.

In Mexico, a number of distortions further impact sprawl. Subsidies for housing tend to favor the development of mass housing projects in the periphery. Furthermore, the budget allocated towards transportation is disproportionately directed to road infrastructure, rather than more sustainable forms of mobility. In 2015, 47 percent of the country's investments were allocated to road infrastructure, while only 6 percent to public transportation. This is strongly disproportionate, as 46 percent of commutes are done by public transport.

When cities are faced with insurmountable traffic congestion, the initial remedy is to build more roads, to alleviate bottlenecks, and to make room for traffic to flow. As American urbanist Lewis Mumford articulated: “Building more roads to prevent congestion is like a fat man loosening his belt to prevent obesity.”

In Mexico City, with an overwhelming problem of vehicular congestion, measures are literally taken to a new level, as authorities have been polemically approving plans to build second-floor highways to alleviate congestion.

Matute explains that increasing road capacity alleviates traffic in the short run, but then encourages more individuals to drive, and only exacerbates the problem over time. This phenomenon, known as induced traffic, continues to mislead transportation planning strategies. Not only is this counterproductive, but it highlights a number of asymmetries as some of these highways are incredibly costly, but still drivers are charged high toll fees for their use, making them inaccessible to large segments of the population.

Another aspect is that building more roads and physical infrastructure fulfills a performative function. As Mature says, visible changes in a city such as extra highways can leave an immediate impression of which politicians can take credit for, and with which authorities want to impress their constituents and have their giant ribbon cutting ceremonies—and this is often not correlated to the good functioning of the city.

Christopher Zegras (Professor of Transportation and Urban Planning in the Dept. of Urban Studies and Planning at MIT) argues that sprawl is detrimental to a city’s environment, as the more expansive a city, the higher its infrastructure costs as well as its energy consumption. He goes on to explain that Mexico City is governed by both centrifugal and centripetal forces, congesting and expanding at the same time. As congestion increases, it causes a slow expansion and outward migration towards the urban periphery, creating cycles of feedback loops. A main issue is that this expansion encroaches onto forests, agriculture lands, and other vital ecosystems on the edges of the city. Additionally, this chaotic expansion has not been commensurate with the delivery of strategic planning and coordination, and the localization of services, as well as mobility investments. The interaction of these factors has had a dire impact on mobility behavior, travel demand, and the environment.

While building more infrastructure can seem like the solution to accommodate a growing population and more vehicular traffic, it is more about building smarter and more efficiently, or essentially about rethinking spatial distribution.



The urban condition is in many ways a condition of congestion. As Zegras claims: “Ultimately, a city with no congestion would be a failure.” Urbanization is indisputably one of the most efficient ways of organizing human societies, but negative externalities of congestion eventually start to push people apart. Harnessing densities can counteract the negative externalities that often accompany processes of urbanization.

Cities are spaces that overlap layers of socio-economic needs, institutions, and infrastructure, but also of personal and collective meaning and memory. Cities respond to our desires to be proximate; our need to achieve varying degrees of efficiency and productivity, and to have access to more opportunities; as well as knowledge spillovers which often come from proximity.

When it comes to the delivery of urban services, agglomerations are efficient. The overlapping of different urban infrastructures, such as mobility, energy, water, and telecommunication networks, are less costly when they are close together. Agglomerations also make cities safer. With more people on the streets there is a tendency for less crime. Living in proximity and coming closer together also has positive impacts on behavioral patterns, interpersonal and social interactions.

Densities are also about creating opportunities, and can be used as mechanisms to avoid brain drain. As Matute explains, in Guatemala there is an explicit strategy to ensure agglomerations in medium-sized cities to retain the population, especially the economically active population, and prevent outward migration. The possibility of developing these intermediate cities with economically active and attractive nodes could also begin to reverse the flow of migration towards the capital city, and hopefully retain some of the population that is leaving in despair to the United States.

Ultimately, agglomerations exist because they are socially attractive and economically efficient. However, it is not about condensing people and infrastructure into tight spaces, but rather about creating compact diverse, mixed-use societies, thus reducing travel distance, car dependency, and freeing up land for conservation, agriculture, and rewilding. In parallel, it seeks to reduce the need for new roads and basic service infrastructure, highways, parking lots, and other inefficient spatial infrastructure required to accommodate the externalities of congestion and sprawl.

Land-use planning instruments fostering density and reducing private vehicle dependency have been revered as the antidote to urban sprawl and car-oriented urbanism. Creating compact, diverse, and mixed-use spaces reduces the need for longer travel distance and thus for motorized vehicles. Transit Oriented Development (TOD) has become a viable strategy to contain urban expansion but also to address some of the most pressing urban problems in developing countries, such as environmental degradation, urban poverty, social segregation, and unequal urban development. In Mexico, it is gaining momentum and increasingly becoming a politically and economically attractive concept for sustainable urban development.

According to a vision scenario, stipulating changes in land-use planning to incentivize density and expanding the public transport infrastructure network could result in a reduction of up to 78 percent in the expected land consumption, as well as up to USD $18 billion (accumulated to 2050) savings in infrastructure costs. Likewise, it could achieve savings of about USD $92 million in energy and almost USD $4 million in water by 2050. It would also result in a 23 percent reduction in annual kilometers traveled by private transport, a half hour in savings on the average daily travel time, and an 8.4 percent reduction in emissions per year.

In essence, densification measures result in a more efficient use of the resources needed for our survival, while leaving room to preserve spaces on the planet that could be better used by other habitats, creatures, and ecosystems. Future trends of urbanization should then focus on curbing the negative externalities of congestion, and fostering the positive impacts of densities.



While the Mayans’ resolve to build more temples to counteract environmental degradation seems quixotic at first glance, it is not so far-flung from our current day obsession with achieving growth while neglecting environmental externalities, or using wrong corrective measures, in spite of clear signals and data. Prioritizing economic growth and political ambition over the well-being of ecosystems, or building more roads and second floor highways to counteract congestion, exemplify some of the misguided pursuits that accelerate urban deterioration. The underlying lesson is that they ultimately failed to achieve balance with their ecosystem and opted for an imaginary that in reality contradicted their pursuits.

The Aztec civilization of Tenochtitlan would have never imagined what their capital would eventually morph into, just as we may not be able to imagine what the fate of Mexico City will be in several decades. Cities are stochastic processes, and like living organisms need to function as adaptive systems. Their capacity to survive is largely dependent on their ability to take new shapes and functions, and to respond to current and future challenges. Ultimately, they should seek to align themselves to the biophysical realities of their ecosystems.

While Mexico City slowly subsides into its porous base, the imminent infrastructural collapse cannot be more evident. Yet more roads will be built, and the city will continue to expand to accommodate a projected population of 30 million by 2030. However, the focus should not rely on building more to accommodate more, but rather on restructuring how cities are managed and planned.

Cities such as Mexico City can have an important role in spearheading a paradigm shift for current systems in place that coherently link with broader socio-ecological interdependencies. If there is anything to learn from the fate of the Maya civilization, it is the need to rethink value-creating mechanisms to ensure human activity and aspirations become more closely interlinked to natural systems. A good start is to reframe patterns of land-use planning, restructure mobility, and encourage densities to make cities more efficient for people as well as ecosystems, aiming to ensure their sustainability.

Photos by Bon Squid

Antonia Burchard-Levine

Antonia is a writer and urban development consultant specialising in transportation and mobility, urban land use, and infrastructure financing. She is an alumna of Strelka Institute's The New Normal Program.

The essay is part of the Cultures of Congestion special project by Strelka and ArtRebels.

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