Can greenery stop murders? In Chicago, one of America’s deadliest cities, two researchers tried to find out. They studied 98 comparable buildings, recording different levels of greenery, and monitoring violent crime figures surrounding each one. The results were clear: the greener the surroundings, the fewer crimes were reported.

Using urban design to discourage violent crime has a rich history, but it could take on new importance in a rapidly urbanising world. Today, 55% of the world’s population lives in urban areas. By 2050, 68% will, threatening to sharpen inequality and encourage the spread of violent crime.

So can policymakers effectively design out crime?

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Planners of the world, unite!

Crime Prevention Through Environmental Design (CPTED, pronounced sep-ted), was born in the 1970s. Its practitioners tried to understand how the built environment could encourage or discourage anti-social or criminal behaviour. Their teachings took off: Canada, the US, Australia, Japan, Colombia and Chile and South Africa have all used CPTED, and in 2007, the UN formally backed incorporating its principles into new settlements.

The term was coined in 1971 by criminologist C. Ray Jeffery, but some of its earliest principles derived from the work of Oscar Newman, an architect. Over the 1970s, their ideas were formalised into a first generation of CPTED which relied on seven distinct strategies, from building open spaces that let citizens keep an eye on each other, to including fences and other "defensive" structures.

“The problem is that half the time, the rules don’t really apply and in some cases, they can be quite harmful”

Countries around the world spent the next two decades investing in street lighting to deter criminals, redeveloping parks and public spaces, and erecting walls, gates and fences to make crime harder to commit. But the first generation of thinking about CPTED soon came under fire.

“It’s all about blanket rules,” said Kees Dorst, Professor of Design at University of Technology Sydney. “The problem is that half the time, the rules don’t really apply and in some cases, they can be quite harmful.”

The “dark side” of CPTED has been extensively examined. “Anti-homeless” spikes provoked outrage in London in 2016, while trends like the growth of gated communities have led to racial and economic segregation in some US cities. “Practitioners were designing for safety, but they weren’t designing for people,” said Professor Lorraine Gamman at the Design Against Crime centre at the University of the Arts, London.

Initially, she argued, CPTED encouraged a view of public space that obsessed over safety and forgot that public spaces don’t just need to be safe — people have to want to use them.

Back to basics

The second phase of CPTED took hold during the 1990s and early 2000s. Early CPTED had ignored the role of social factors in crime, a new generation of planners and criminologists argued, and the approach had often failed to take in the wishes and wisdom of residents. Second-generation CPTED tried to put the community first, focusing on the social function of public space and engaging residents in the design process.

The value of community engagement in urban design is perhaps best illustrated in South America. When the city of Medellín, Colombia, built cable cars to connect its most deprived favelas to the rest of the city, it consulted residents extensively on what they needed and wanted from redevelopment. Its murder rate plummeted: one of its most dangerous favelas saw the number of homicides plummet from 293 in 2001 to just 15 in 2016.

“Practitioners were designing for safety, but they weren’t designing for people”

Numerous cities tried and failed to replicate Medellin’s success. Rio de Janeiro was one. A cable car was built to connect the favelas to the city. But nobody used it: only 8% of the population. When the favela lacked sanitation and basic services, a cable car was not what the residents wanted. The project collapsed and the cable car is now out of use. The community was overlooked, and the project failed because of it.

So how can we ensure CPTED’s success?

Designing the future

The problem with the first generation of CPTED was its rule-based rigidity, so designing a set checklist of the second generation’s thinking is wrong-headed, argues Gamman. But three approaches can encourage success — or at least stave off the most egregious failures.

First, is engaging with the community, and not just treating engagement as a buzzword. “Working from the top-down just doesn’t work,” said Gamman. To make citizen engagement more meaningful, people need to be involved in the process of designing new spaces — not just offered one or two options.

“You have to look at what you want more of — such as conviviality — as well as what you want less of, such as crime”

Engaging communities can happen in different ways: in some cases, town hall meetings might work. In others, using interactive technology and games — such as Minecraft — have given residents a voice in the design process.

Second, is understanding the problem. “Every design has to be situated,” said Dorst. Seeing where crime happens is not enough: understanding how non-criminal residents use spaces, how they feel about those spaces, and what kinds of crime they are most worried by are all integral to finding solutions. The success of CPTED stands or falls on its ability to slot into local spaces and cultures.

Third is remembering what public spaces are for. “You have to look at what you want more of — such as conviviality — as well as what you want less of, such as crime,” said Gamman. Turning cities into fortresses might cut crime, but if nobody wants to live there, the victory is pyrrhic at best. — Edward Siddons

(Picture Credit: Flickr/Duncan Rawlinson)