Crime Prevention Through Environmental Design

This blog is a part of our series, “Perspectives in Crime” where we explore leading academic studies that touch on crime data.

The built environment plays a crucial role in the prevention of crime. Though much of criminology and crime prevention focuses on the factors that produce victims and offenders, an increasing body of contemporary work is focused on where crimes occur and how the built environment can encourage or discourage criminal activity.

These practices are not new. History is full of examples of the built environment being used to protect against threats, famously with the fortresses and castles of the iron age. However, similar principles can be applied to modern buildings, street design, and urban planning. Research has shown that these designs can impact the vulnerability and susceptibility of the people and businesses who reside in these spaces. This contemporary work is called Crime Prevention Through Environmental Design (CPTED), a multidisciplinary concept with a basis in environmental and behavioral psychology.

In prior Perspective in Crime blogs, we have highlighted how a relatively small number of addresses generate a significant majority of police calls — Crime Trends and Micro Places — which provides statistics and sheds light on the importance of how specific environments and design choices can affect local crime.

When applied to routine activity theory, where crime occurs when a motivated offender encounters a suitable target lacking guardianship, we can see how crime deterrence through design both makes targets less suitable and increases guardianship.

The principles of crime prevention through environmental design (CPTED)

The term "crime prevention through environmental design was coined by criminologist C. Ray Jeffrey in his 1971 book of the same name. Many of the core ideas contributing to CPTED are owed to the concepts of defensible space, developed by architect and theorist Oscar Newman in the early 1970s. Newman’s principles revolved around the ideas of natural surveillance, territorial reinforcement, and access control.

• Natural surveillance means clear lines of sight and landscaping that discourages hiding spaces as well as thorough lighting that can increase the sense of informal guardianship and discourage would-be offenders.
• Territorial reinforcement is the use of fences, walls, or even landscape architecture features like trees, shrubs, or hedges to clearly delineate where the boundary of private space begins. This idea can also include the use of signage to denote no trespassing or unauthorized personnel.
• Access control is the idea of using security gates, door codes, or security guards to prevent unauthorized access to an area.

These concepts increase the sense of guardianship both to potential criminals scouting a space and also to the people who live, work, or otherwise utilize these spaces daily.

CPTED also details the rigorous upkeep of buildings and public spaces, the removal of graffiti and other signs of disorder, as well as even extending to planted flora and fauna, the public display of art, and calming music in public areas. By implementing these measures, inhabitants are encouraged to actively invest in their environments and foster a sense of communal care, producing a greater degree of informal guardianship.

CPTED’s guiding principles work to prevent crime in numerous ways, affecting both the opportunities and the motivation to commit crimes. These ideas go hand in hand with target-hardening approaches like improved lighting, cameras in vulnerable areas, and guardianship, all making criminal behavior more likely to be exposed and witnessed, reducing the odds that a prospective offender will choose this space as a criminal target.

The psychological impact of CPTED: risk reduction and community building

The psychological effects of CPTED extend beyond potential offenders, with proponents arguing there are many positive effects that can be felt by the people who use these spaces, including a diminished sense of risk and increased community. Criminologists believe that these defensible space values increase the likelihood of legitimate users of the space reporting people that stood out to them as illegitimate users. “Environmental cues within the built form are perceived and decoded and can influence the way people react to an environment.” (Cozens and Love 2015)

Though many of the principles of target hardening relate to the tenets of defensible space and CPTED, Criminologists working in CPTED warn of the dangers of fortressification where too many visual cues of security are present and can in fact cause residents to “withdraw behind their domestic physical barriers.” (Cozens and Love 2015)

These concerns impacted the development of second-generation CPTED, which places additional emphasis on social cohesion, community connectivity, community culture, and threshold capacity.

• Social cohesion means creating an environment of mutual respect regarding the similarities and differences of people in a community.
• Community connectivity and culture emphasize well-connected integrated communities that share a sense of place. Local events and a sense of neighborhood can help to encourage pro-social behaviors resulting in meaningful, supportive guardianship among legitimate users of a space.
• Threshold capacity refers to the amount of traffic and activity an environment is designed to maintain and cautions that when this capacity is breached, an environment becomes more disordered and more susceptible to crime.

Overcoming challenges: unlocking CPTED's impact

CPTED is employed today in many settings across the world — in residential spaces, commercial areas, public transit hubs, and sports stadiums. Gathering empirical evidence of the total effect of CPTED is challenging, as interpretations of CPTED's values differ in execution, and each circumstance faces many other unique factors concerning local crime and socio-economic pressures before the implementation of CPTED. But many studies have observed that CPTED features have salient meaningful impacts on local crime. A 1996 study of the Five Oaks project in Ohio found a 26% reduction in recorded crime after the implementation of CPTED measures. The reduction in crime also increased occupancy rates. A US Department of Justice report from the year 2000 reviewed over 100 police department crime reduction projects and found that 57% of successful projects were based on CPTED strategies.

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