How to Design Safer Cities

Copenhagen, Superkilen

Can a good public space influence social behavior and make a city more secure?

In 1969, Philip Zimbardo, professor at the University of Stanford, performed a social psychological experiment. He placed an unlicensed car with a lifted hood in a neglected street in The Bronx, New York, and another similar car in a wealthy neighborhood of Palo Alto, California. The car in The Bronx was attacked in less than ten minutes, its apparent state of abandonment enabling the looting. The car in Palo Alto, however, remained untouched for more than a week.

Zimbardo then took his experiment one step further and broke a window of the car in Palo Alto. Almost immediately, passersby began to take things out of the car and within a few hours, the car had been completely dismantled. In both cases, many of the looters did not appear to be dangerous people. This experiment lead Harvard Professors George Kelling and James Wilson to develop the Broken Windows Theory in 1982: “If a broken window is left without repair, people will come to the conclusion that no one cares about it and that there is no one watching it. Then more windows will be broken and the lack of control will spread from the buildings to the streets, sending a signal that anything goes and that there is no authority.”

Read more about designing safer cities after the break...

Following this, Kelling was hired – much earlier than Rudy Giuliani and his Zero Tolerance Policy – by the Subway Advisory of New York, where insecurity and crime reigned. His first challenge was to convince the progressive city mayor, then Democrat Ed Koch, that the solution was not to create more policy and make more arrests, as the majority claimed, but to clean and systematically prevent graffiti in and on the subway wagons, to make sure that everyone paid for their tickets, and to eradicate vagrancy in the subway. Despite the barrage of criticism, the transformation of the New York Subway commenced through concrete symbols and visible details that reestablished order and authority. Even the famed designer Massimo Vignelli, author of the signposting, decided to invert the colors of his posters to white typography on black background to discourage graffiti artists. Today, the New York subway is a model of a secure and efficient public space and an emblem that New Yorkers are not willing to compromise again.

The idea is simple, but powerful: bad habits spread quickly, but good ones, with strength and continuity, can displace the bad. How many things decline because of our indifference to the very first signs that something isn’t right? How many "broken windows" do we see each day? 

It’s all about marking the limits and nullifying bad practices and habits with situational and preventative strategies that engage, not only the authorities, but also the community in resolving problems through active participation. It’s also about vindicating the role of the State in the regulation and control of an area where general interests should always take priority, small or large and with or without justification. In contrast to what many claim from an erroneous libertarian perspective, democratic coexistence in the public realm requires the restriction of individual liberties in order to maximize a public space’s good use and collective enjoyment.

Some of the most successful cities dealing with this situation have escaped their spiraling deterioration with proactive planning of high quality design, a culture of urban hygiene and constant maintenance, or as the ex-mayor of Curitiba, Jaime Lerner, likes to say: “obsession with urban acupuncture.”

One of the first to raise questions concerning public space was Jane Jacobs, a famous and controversial civil rights activist in New York. Initially ridiculed by the technocrats of urban modernism, today she is vindicated and cited even by President Obama himself. In her book “Death and Life of Great American Cities” (1962) she rescues the rich preexistences of multifunctional cities, compact and dense where the street, the neighborhood and the community are vital to the urban culture. “To maintain the security of the city is the principal job of the streets and sidewalks.” For her, a secure street is one that proposes a clear delimitation between public and private space, with people and constant movement, as well as small blocks that generate numerous corners and intersections, where the buildings look to the curb so that many eyes keep watch over it.

The future of humanity and of the planet depends on having better cities. We know that pulling back to private space and fleeing to unsustainable urban peripheries is not the solution and only aggravates the problem. Our “quality of life” cannot depend on ghettos guarded by walls, alarms and private armies. Reducing insecurity and fear is as much of a priority as making these neglected areas more efficient, integrated and creative. We should begin to look at public space as the heart of modern life; its design, its use, its management and its new functions are all vital. We should rethink the street, the plaza and the park, the woodland and the urban landscape and all that which permits us to construct an identity and to experience the encounter, the interchange and the difference. “A site only becomes a place when we appropriate it culturally,” says Heidegger.

Recent investigations demonstrate that these interactions between urban design, community and public space are effective complements to a policy of consistent security. Bill Hiller, Professor at the University of London in his Laboratory of Spatial Syntax, investigates and maps flows between crime, place and population. Millions of pieces of data gathered and years of analysis have permitted him to conclude, similarly to Jacobs, that the compact and dense city is safer than residential neighborhoods with low density. Mono-functional zones with little housing presence – that lose vitality and pedestrian activity at a certain hour – are also less safe. The street again becomes a key and multi-dimensional part of the city, a tightly woven fabric between buildings that conform to a grid with higher population density. Towers with bars or walls to the street and inbred shopping malls that isolate themselves from public space, however, do not help the situation. The ideal kind of city consists of blocks with businesses on the first floor and apartment buildings on the upper floors, conforming streets and animated and heterogeneous neighborhoods that mix distinct types of people and activities; from educational, cultural and institutional to commercial, touristic and environmentally friendly production.

Security problems should be part of the urbanist normative as well as part of the initial challenges of architecture and public works projects. The current anxieties and impossibilities we face challenge us to demand more of ourselves and  to innovate with new logics, in order to create a city with greater participation and less speculation. 

This text was translated from Plataforma Urbana.

About this author
Cite: Barbara Porada. "How to Design Safer Cities" 19 Feb 2013. ArchDaily. Accessed . <> ISSN 0719-8884

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