Crime prevention through environmental design
Encyclopedia
Crime prevention through environmental design (CPTED) is a multi-disciplinary approach to deterring criminal
behavior through environmental design
. CPTED strategies rely upon the ability to influence offender decisions that precede criminal acts. , most implementations of CPTED occur solely within the built environment
.
, was developed concurrently by architect
Oscar Newman. Both men built on the previous work of Elizabeth Wood
, Jane Jacobs
and Schlomo Angel. Jeffery's book, "Crime Prevention Through Environmental Design" came out in 1971, but his work was ignored throughout the 1970s. Newman's book, "Defensible Space: - Crime Prevention through Urban Design
" came out in 1972. His principles were widely adopted but with mixed success. The defensible space approach was subsequently revised with additional built environment approaches supported by CPTED. Newman represented this as CPTED and credited Jeffery as the originator of the CPTED term. Newman's CPTED-improved defensible space approach enjoyed broader success and resulted in a reexamination of Jeffery's work. Jeffery continued to expand the multi-disciplinary aspects of the approach, advances which he published, with the last one published in 1990. The Jeffery CPTED model is more comprehensive than the Newman CPTED model, which limits itself to the built environment. Later models of CPTED were developed based on the Newman Model, with Crowe's being the most popular.
, CPTED is popularly understood to refer strictly to the Newman/Crowe type models, with the Jeffery model treated more as multi-disciplinary approach to crime prevention which incorporates biology and psychology, a situation accepted even by Jeffery himself. (Robinson, 1996). A revision of CPTED, initiated in 1997, termed 2nd Generation CPTED, adapts CPTED to offender individuality, further indication that Jeffery's work is not popularly considered to be already a part of CPTED.
issues while working with the Chicago Housing Authority
, placing emphasis on design features that would support natural surveillability. Her guidelines were never implemented but stimulated some of the original thinking that led to CPTED.
Jane Jacobs' book, The Death and Life of Great American Cities
(1961) argued that urban diversity and vitality were being destroyed by urban planner
s and their urban renewal
strategies. She was challenging the basic tenets of urban planning
of the time: that neighborhoods should be isolated from each other; that an empty street
is safer than a crowded one; and that the car
represents progress over the pedestrian
. An editor for Architectural Forum
magazine (1952–1964), she had no formal training in urban planning, but her work emerged as a founding text for a new way of seeing cities. She felt that the way cities were being designed and built meant that the general public would be unable to develop the social framework needed for effective self-policing. She pointed out that the new forms of urban design broke down many of the traditional controls on criminal behavior, for example, the ability of residents to watch the street and the presence of people using the street both night and day. She suggested that the lack of "natural guardianship" in the environment promoted crime
. Jacobs developed the concept that crime flourishes when people do not meaningfully interact with their neighbors. In Death and Life, Jacobs listed the three attributes needed to make a city street safe: a clear demarcation of private
and public space
; diversity of use; and a high level of pedestrian use of the sidewalk
s.
Schlomo Angel was an early pioneer of CPTED and studied under noted planner Christopher Alexander
. Angel's Ph.D.
thesis, Discouraging Crime Through City Planning, (1968) was a study of street crime
in Oakland
, CA. In it he states "The physical environment can exert a direct influence on crime settings by delineating territories, reducing or increasing accessibility by the creation or elimination of boundaries and circulation networks, and by facilitating surveillance
by the citizenry and the police
." He asserted that crime was inversely related to the level of activity on the street, and that the commercial
strip environment was particularly vulnerable to crime because it thinned out activity, making it easier for individuals to commit street crime. Angel developed and published CPTED concepts in 1970 in work supported and widely distributed by the United States Department of Justice
(Luedtke, 1970).
. The phrase began to gain acceptance after the publication of his 1971 book of the same name.
For reasons that have received little attention, Jeffery's work was ignored throughout the 1970s. Jeffrey's own explanation is that, at a time when the world wanted prescriptive design solutions, his work presented a comprehensive theory and used it to identify a wide range of crime prevention functions that should drive design and management standards.
Concurrent with Jeffery's largely theoretical work was Oscar Newman and George Rand's empirical
study
of the crime-environment connection conducted in the early 1970s. As an architect, Newman placed emphasis on the specific design features, an emphasis missing in Jeffery's work. Newman's "Defensible Space - Crime Prevention through Urban Design (1972) includes extensive discussion of crime related to the physical form of housing based on crime data analysis from New York City public housing. "Defensible Space" changed the nature of the crime prevention and environmental design field and within two years of its publication substantial federal funding was made available to demonstrate and study defensible space concepts.
As established by Newman, defensible space must contain two components. First, defensible space should allow people to see and be seen continuously. Ultimately, this diminishes residents fear because they know that a potential offender can easily be observed, identified, and consequently, apprehended. Second, people must be willing to intervene or report crime when it occurs. By increasing the sense of security in settings where people live and work, it encourages people to take control of the areas and assume a role of ownership. When people feel safe in their neighborhood they are more likely to interact with one another and intervene when crime occurs. These remain central to most implementations of CPTED .
In 1977, Jeffery's second edition of Crime Prevention Through Environmental Design expanded his theoretical approach to embrace a more complex model
of behavior
in which variable physical environments, offender behavior as individuals and behavior of individual members of the general public have reciprocal influences on one another. This laid the foundation for Jeffery to develop a behavioral model aimed at predicting the effects of modifying both the external environment and the internal environment of individual offenders.
Crime Prevention Through Environmental Design (1991) by criminologist Tim Crowe provided a solid base for CPTED to move forward into the rest of the 1990s.
From 1994 through 2002, Sparta Consulting Corporation led by Severin Sorensen, CPP managed the US Government's largest CPTED technical assistance and training program titled Crime Prevention Through Environmental Design (CPTED) in Public Housing Technical Assistance and Training Program, funded by the US Department of Housing and Urban Development. During this period Sorensen worked with Ronald V. Clarke and the Sparta team to develop a new CPTED Curriculum that used Situational Crime Prevention as an underlying theoretical basis for CPTED measures. A curriculum was developed and trained to stakeholders in public and assisted housing, and follow-up CPTED assessments were conducted at various sites. The Sparta led CPTED projects showed statistical reductions in self reported FBI UCR Part I crimes between 17% to 76% depending on the basket of CPTED measures employed in specific high crime, low income settings in the United States.
In 1996, Oscar Newman published an update to his earlier CPTED works, titled, Creating Defensible Space, Institute for Community Design Analysis, Office of Planning and Development Research (PDR), US Department of Housing and Urban Development (HUD).
In 1997, an article by Greg Saville and Gerry Cleveland, 2nd Generation CPTED, exhorted CPTED practitioners to consider the original social ecology origins of CPTED, including social and psychological issues beyond the built environment.
Consistent with the widespread implementation of defensible space guidelines in the 1970s, most implementations of CPTED are based solely upon the theory that the proper design and effective use of the built environment can reduce crime, reduce the fear of crime, and improve the quality of life. Built environment implementations of CPTED seek to dissuade offenders from committing crimes by manipulating the built environment in which those crimes proceed from or occur. The three most common built environment strategies are natural surveillance, natural access control and natural territorial reinforcement.
Natural surveillance and access control strategies limit the opportunity for crime. Territorial reinforcement promotes social control through a variety of measures.
. Potential offenders feel increased scrutiny and limitations on their escape routes.
Natural surveillance measures can be complemented by mechanical and organizational measures. For example, closed-circuit television
(CCTV) cameras can be added in areas where window surveillance is unavailable.
Natural access control is used to complement mechanical and operational access control measures, such as target hardening
.
An environment designed to clearly delineate private space does two things. First, it creates a sense of ownership. Owners have a vested interest and are more likely to challenge intruders or report them to the police. Second, the sense of owned space creates an environment where "strangers" or "intruders" stand out and are more easily identified. By using buildings, fences, pavement, signs, lighting and landscape to express ownership and define public, semi-public and private space, natural territorial reinforcement occurs. Additionally, these objectives can be achieved by assignment of space to designated users in previously unassigned locations.
Territorial reinforcement measures make the normal user feel safe and make the potential offender aware of a substantial risk of apprehension or scrutiny.
approach to property maintenance, observing that the presence of a broken window will entice vandals to break more windows in the vicinity. The sooner broken windows are fixed, the less likely it is that such vandalism will occur in the future.
ers, land managers, community activists, and law enforcement professionals.
In terms of effectiveness, a more accurate title for the strategy would be crime deterrence through environmental design. Research demonstrates that offenders cannot be literally prevented from committing crimes by using CPTED. CPTED relies upon changes to the physical environment that will cause an offender to make certain behavioral decisions. Those changes are crafted so as to encourage behavior, and thus they deter rather than conclusively "prevent" behavior.
Beyond the attraction of being cost effective in lowering the incidence of crime, CPTED typically reduces the overall costs of preventing crime. Retrofitting an existing environment to meet CPTED can sometimes be costly, but when incorporated in the original design phase of facility planning, cost of designing to CPTED principles are often lower than with traditional approaches. Operational costs are often lower also, as CPTED lighting designs can significantly lower energy use. Adding to the attraction of CPTED is that it lowers liability.
The area of liability has led to the questioning of how much crime prevention is really necessary for a given place. It has been mooted that a risk management approach might be superior to a fear-driven one. The question is, "does a community give up too much freedom, usually in terms of movement and assembly, to be free from fear of crime?" This was a question that was not widely asked in the 1990s; note the rise around the world of gated communities and the use of CCTV
in public spaces.
First is a lack of knowledge of CPTED by environmental designers, land managers, and individual community members. For this reason, allocating substantial resources to community educational programs are often required.
The second major obstacle is resistance to change. Many specifically resist the type of cooperative planning that is required to use CPTED. Beyond that, skeptics reject the research and historic precedents that support the validity of CPTED concepts.
The third obstacle is the perception that CPTED claims to be a panacea for crime
that will be used to displace other more traditional approaches rather than a small, but important, complementary tool in deterring offender behavior.
The fourth obstacle is that many existing built areas were not designed with CPTED in mind, and modification would be expensive, politically difficult, or require significant changes in some areas of the existing built environment.
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...
behavior through environmental design
Environmental design
Environmental design is the process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products...
. CPTED strategies rely upon the ability to influence offender decisions that precede criminal acts. , most implementations of CPTED occur solely within the built environment
Built environment
The term built environment refers to the human-made surroundings that provide the setting for human activity, ranging in scale from personal shelter and buildings to neighborhoods and cities that can often include their supporting infrastructure, such as water supply or energy networks.The built...
.
History
CPTED was originally coined and formulated by criminologist C. Ray Jeffery. A more limited approach, termed defensible spaceDefensible Space Theory
The defensible space theory of architect and city planner Oscar Newman encompasses ideas about crime prevention and neighborhood safety. The theory developed in the early 1970s, and he wrote his first book on the topic, Defensible Space in 1972...
, was developed concurrently by architect
Architect
An architect is a person trained in the planning, design and oversight of the construction of buildings. To practice architecture means to offer or render services in connection with the design and construction of a building, or group of buildings and the space within the site surrounding the...
Oscar Newman. Both men built on the previous work of Elizabeth Wood
Elizabeth Wood (executive)
Elizabeth Wood was the first Executive Director of the Chicago Housing Authority.Born to missionary parents in Japan, Elizabeth Wood was educated at Illinois Wesleyan University and at the University of Michigan where she received both Bachelor's and Master's degrees in rhetoric...
, Jane Jacobs
Jane Jacobs
Jane Jacobs, was an American-Canadian writer and activist with primary interest in communities and urban planning and decay. She is best known for The Death and Life of Great American Cities , a powerful critique of the urban renewal policies of the 1950s in the United States...
and Schlomo Angel. Jeffery's book, "Crime Prevention Through Environmental Design" came out in 1971, but his work was ignored throughout the 1970s. Newman's book, "Defensible Space: - Crime Prevention through Urban Design
Urban design
Urban design concerns the arrangement, appearance and functionality of towns and cities, and in particular the shaping and uses of urban public space. It has traditionally been regarded as a disciplinary subset of urban planning, landscape architecture, or architecture and in more recent times has...
" came out in 1972. His principles were widely adopted but with mixed success. The defensible space approach was subsequently revised with additional built environment approaches supported by CPTED. Newman represented this as CPTED and credited Jeffery as the originator of the CPTED term. Newman's CPTED-improved defensible space approach enjoyed broader success and resulted in a reexamination of Jeffery's work. Jeffery continued to expand the multi-disciplinary aspects of the approach, advances which he published, with the last one published in 1990. The Jeffery CPTED model is more comprehensive than the Newman CPTED model, which limits itself to the built environment. Later models of CPTED were developed based on the Newman Model, with Crowe's being the most popular.
, CPTED is popularly understood to refer strictly to the Newman/Crowe type models, with the Jeffery model treated more as multi-disciplinary approach to crime prevention which incorporates biology and psychology, a situation accepted even by Jeffery himself. (Robinson, 1996). A revision of CPTED, initiated in 1997, termed 2nd Generation CPTED, adapts CPTED to offender individuality, further indication that Jeffery's work is not popularly considered to be already a part of CPTED.
1960s
In the 1960s Elizabeth Wood developed guidelines for addressing securitySecurity
Security is the degree of protection against danger, damage, loss, and crime. Security as a form of protection are structures and processes that provide or improve security as a condition. The Institute for Security and Open Methodologies in the OSSTMM 3 defines security as "a form of protection...
issues while working with the Chicago Housing Authority
Chicago Housing Authority
The Chicago Housing Authority is a municipal corporation established by the State of Illinois in 1937 with jurisdiction for the administrative oversight of public housing within the City of Chicago...
, placing emphasis on design features that would support natural surveillability. Her guidelines were never implemented but stimulated some of the original thinking that led to CPTED.
Jane Jacobs' book, The Death and Life of Great American Cities
The Death and Life of Great American Cities
The Death and Life of Great American Cities, by Jane Jacobs, is a greatly influential book on the subject of urban planning in the 20th century...
(1961) argued that urban diversity and vitality were being destroyed by urban planner
Urban planner
An urban planner or city planner is a professional who works in the field of urban planning/land use planning for the purpose of optimizing the effectiveness of a community's land use and infrastructure. They formulate plans for the development and management of urban and suburban areas, typically...
s and their urban renewal
Urban renewal
Urban renewal is a program of land redevelopment in areas of moderate to high density urban land use. Renewal has had both successes and failures. Its modern incarnation began in the late 19th century in developed nations and experienced an intense phase in the late 1940s – under the rubric of...
strategies. She was challenging the basic tenets of urban planning
Urban planning
Urban planning incorporates areas such as economics, design, ecology, sociology, geography, law, political science, and statistics to guide and ensure the orderly development of settlements and communities....
of the time: that neighborhoods should be isolated from each other; that an empty street
Street
A street is a paved public thoroughfare in a built environment. It is a public parcel of land adjoining buildings in an urban context, on which people may freely assemble, interact, and move about. A street can be as simple as a level patch of dirt, but is more often paved with a hard, durable...
is safer than a crowded one; and that the car
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
represents progress over the pedestrian
Pedestrian
A pedestrian is a person traveling on foot, whether walking or running. In some communities, those traveling using roller skates or skateboards are also considered to be pedestrians. In modern times, the term mostly refers to someone walking on a road or footpath, but this was not the case...
. An editor for Architectural Forum
Architectural Forum
Architectural Forum was an American magazine that covered the home-building industry and architecture. Started in 1892, it absorbed the magazine Architect's world in October 1938, and ceased publication in 1974.-Other titles:...
magazine (1952–1964), she had no formal training in urban planning, but her work emerged as a founding text for a new way of seeing cities. She felt that the way cities were being designed and built meant that the general public would be unable to develop the social framework needed for effective self-policing. She pointed out that the new forms of urban design broke down many of the traditional controls on criminal behavior, for example, the ability of residents to watch the street and the presence of people using the street both night and day. She suggested that the lack of "natural guardianship" in the environment promoted crime
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...
. Jacobs developed the concept that crime flourishes when people do not meaningfully interact with their neighbors. In Death and Life, Jacobs listed the three attributes needed to make a city street safe: a clear demarcation of private
Private sector
In economics, the private sector is that part of the economy, sometimes referred to as the citizen sector, which is run by private individuals or groups, usually as a means of enterprise for profit, and is not controlled by the state...
and public space
Public space
A public space is a social space such as a town square that is open and accessible to all, regardless of gender, race, ethnicity, age or socio-economic level. One of the earliest examples of public spaces are commons. For example, no fees or paid tickets are required for entry, nor are the entrants...
; diversity of use; and a high level of pedestrian use of the sidewalk
Sidewalk
A sidewalk, or pavement, footpath, footway, and sometimes platform, is a path along the side of a road. A sidewalk may accommodate moderate changes in grade and is normally separated from the vehicular section by a curb...
s.
Schlomo Angel was an early pioneer of CPTED and studied under noted planner Christopher Alexander
Christopher Alexander
Christopher Wolfgang Alexander is a registered architect noted for his theories about design, and for more than 200 building projects in California, Japan, Mexico and around the world...
. Angel's Ph.D.
Doctor of Philosophy
Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil , in English-speaking countries, is a postgraduate academic degree awarded by universities...
thesis, Discouraging Crime Through City Planning, (1968) was a study of street crime
Street crime
Street crime is a loose term for criminal offences taking place in public places. It has moved to occupy the place once held by mugging. According to London's Metropolitan Police Force, street crime is:...
in Oakland
Oakland, California
Oakland is a major West Coast port city on San Francisco Bay in the U.S. state of California. It is the eighth-largest city in the state with a 2010 population of 390,724...
, CA. In it he states "The physical environment can exert a direct influence on crime settings by delineating territories, reducing or increasing accessibility by the creation or elimination of boundaries and circulation networks, and by facilitating surveillance
Surveillance
Surveillance is the monitoring of the behavior, activities, or other changing information, usually of people. It is sometimes done in a surreptitious manner...
by the citizenry and the police
Police
The police is a personification of the state designated to put in practice the enforced law, protect property and reduce civil disorder in civilian matters. Their powers include the legitimized use of force...
." He asserted that crime was inversely related to the level of activity on the street, and that the commercial
Commerce
While business refers to the value-creating activities of an organization for profit, commerce means the whole system of an economy that constitutes an environment for business. The system includes legal, economic, political, social, cultural, and technological systems that are in operation in any...
strip environment was particularly vulnerable to crime because it thinned out activity, making it easier for individuals to commit street crime. Angel developed and published CPTED concepts in 1970 in work supported and widely distributed by the United States Department of Justice
United States Department of Justice
The United States Department of Justice , is the United States federal executive department responsible for the enforcement of the law and administration of justice, equivalent to the justice or interior ministries of other countries.The Department is led by the Attorney General, who is nominated...
(Luedtke, 1970).
1970s
The phrase crime prevention through environmental design (CPTED) was first used by C. Ray Jeffery, a criminologist from Florida State UniversityFlorida State University
The Florida State University is a space-grant and sea-grant public university located in Tallahassee, Florida, United States. It is a comprehensive doctoral research university with medical programs and significant research activity as determined by the Carnegie Foundation...
. The phrase began to gain acceptance after the publication of his 1971 book of the same name.
- Jeffery's work was based on the precepts of experimental psychologyPsychologyPsychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
represented in modern learning theoryTheoryThe English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
. (Jeffery and Zahm, 1993:329) Jeffery's CPTED concept arose out of his experiences with a rehabilitative project in Washington, D.C. that attempted to control the school environment of juveniles in the area. Rooted deeply in the psychological learning theory of B.F. Skinner, Jeffery's CPTED approach emphasized the role of the physical environment in the development of pleasurable and painful experiences for the offender that would have the capacity to alter behavioral outcomes. His original CPTED model was a stimulus-response (S-R) model positing that the organism learned from punishments and reinforcements in the environment. Jeffery "emphasized material rewards . . . and the use of the physical environment to control behavior" (Jeffery and Zahm, 1993:330). The major idea here was that by removing the reinforcements for crime, it would not occur. (Robinson, 1996)
For reasons that have received little attention, Jeffery's work was ignored throughout the 1970s. Jeffrey's own explanation is that, at a time when the world wanted prescriptive design solutions, his work presented a comprehensive theory and used it to identify a wide range of crime prevention functions that should drive design and management standards.
Concurrent with Jeffery's largely theoretical work was Oscar Newman and George Rand's empirical
Empirical
The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....
study
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
of the crime-environment connection conducted in the early 1970s. As an architect, Newman placed emphasis on the specific design features, an emphasis missing in Jeffery's work. Newman's "Defensible Space - Crime Prevention through Urban Design (1972) includes extensive discussion of crime related to the physical form of housing based on crime data analysis from New York City public housing. "Defensible Space" changed the nature of the crime prevention and environmental design field and within two years of its publication substantial federal funding was made available to demonstrate and study defensible space concepts.
As established by Newman, defensible space must contain two components. First, defensible space should allow people to see and be seen continuously. Ultimately, this diminishes residents fear because they know that a potential offender can easily be observed, identified, and consequently, apprehended. Second, people must be willing to intervene or report crime when it occurs. By increasing the sense of security in settings where people live and work, it encourages people to take control of the areas and assume a role of ownership. When people feel safe in their neighborhood they are more likely to interact with one another and intervene when crime occurs. These remain central to most implementations of CPTED .
In 1977, Jeffery's second edition of Crime Prevention Through Environmental Design expanded his theoretical approach to embrace a more complex model
Mathematical model
A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used not only in the natural sciences and engineering disciplines A mathematical model is a...
of behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...
in which variable physical environments, offender behavior as individuals and behavior of individual members of the general public have reciprocal influences on one another. This laid the foundation for Jeffery to develop a behavioral model aimed at predicting the effects of modifying both the external environment and the internal environment of individual offenders.
1980s
By the 1980s, the defensible space prescriptions of the 1970s were determined to have mixed effectiveness. They worked best in residential settings, especially in settings where the residents were relatively free to respond to cues to increase social interaction. Defensible space design tools were observed to be marginally effective in institutional and commercial settings. As a result, Newman and others moved to improve defensible space, adding CPTED based features. They also deemphasised less effective aspects of defensible space. Contributions to the advance of CPTED in the 1980s included:- The "broken windows" theory, put forth by James Q. WilsonJames Q. WilsonJames Q. Wilson is an American academic political scientist and an authority on public administration. He is a professor and senior fellow at the Clough Center for the Study of Constitutional Democracy at Boston College....
and George L. KellingGeorge L. KellingGeorge L. Kelling is an American criminologist, Professor at Rutgers University, a Research Fellow at Harvard University, and an Adjunct Fellow at the Manhattan Institute. He previously taught at Northeastern University....
in 1982, explored the impact that visible deterioration and neglect in neighborhoods have on behavior. Property maintenance was added as a CPTED strategy on par with surveillance, access control and territoriality. - Canadian academicians Patricia and Paul Brantingham published Environmental Criminology in 1981. According to the authors, a crime takes place when all of the essential elements are present. These elements consist of: a law, an offender, a target, and a place. They characterize these as "the four dimensions of crime", with environmental criminology studying the last of the four dimensions.
- British criminologists Ronald Clark and Patricia Mayhew developed their "situational crime prevention" approach: reducing opportunity to offend by improving design and management of the environment.
- Criminologist Timothy Crowe developed his CPTED training programs.
1990s
Criminology: An Interdisciplinary Approach (1990), was Jeffery's final contribution to CPTED. The Jeffery CPTED model evolved to one which assumes that- The environment never influences behavior directly, but only through the brain. Any model of crime prevention must include both the brain and the physical environment. ... Because the approach contained in Jeffery's CPTED model is today based on many fields, including scientific knowledge of modern brain sciences, a focus on only external environmental crime prevention is inadequate as it ignores another entire dimension of CPTED -- i.e., the internal environment. (Robinson, 1996)
Crime Prevention Through Environmental Design (1991) by criminologist Tim Crowe provided a solid base for CPTED to move forward into the rest of the 1990s.
From 1994 through 2002, Sparta Consulting Corporation led by Severin Sorensen, CPP managed the US Government's largest CPTED technical assistance and training program titled Crime Prevention Through Environmental Design (CPTED) in Public Housing Technical Assistance and Training Program, funded by the US Department of Housing and Urban Development. During this period Sorensen worked with Ronald V. Clarke and the Sparta team to develop a new CPTED Curriculum that used Situational Crime Prevention as an underlying theoretical basis for CPTED measures. A curriculum was developed and trained to stakeholders in public and assisted housing, and follow-up CPTED assessments were conducted at various sites. The Sparta led CPTED projects showed statistical reductions in self reported FBI UCR Part I crimes between 17% to 76% depending on the basket of CPTED measures employed in specific high crime, low income settings in the United States.
In 1996, Oscar Newman published an update to his earlier CPTED works, titled, Creating Defensible Space, Institute for Community Design Analysis, Office of Planning and Development Research (PDR), US Department of Housing and Urban Development (HUD).
In 1997, an article by Greg Saville and Gerry Cleveland, 2nd Generation CPTED, exhorted CPTED practitioners to consider the original social ecology origins of CPTED, including social and psychological issues beyond the built environment.
2000s
, elements of the CPTED approach have gained wide international acceptance due to law enforcement attempts to embrace it. The CPTED term "environment" is commonly used to refer to the external environment of the place. Jeffrey's intention that CPTED also embrace the internal environment of the offender seems to have been lost, even on those promoting the expansion of CPTED to include social ecology and psychology under the banner of 2nd Generation CPTED.Strategies for the built environment
CPTED strategies rely upon the ability to influence offender decisions that precede criminal acts. Research into criminal behavior shows that the decision to offend or not to offend is more influenced by cues to the perceived risk of being caught than by cues to reward or ease of entry. Consistent with this research, CPTED based strategies emphasise enhancing the perceived risk of detection and apprehension.Consistent with the widespread implementation of defensible space guidelines in the 1970s, most implementations of CPTED are based solely upon the theory that the proper design and effective use of the built environment can reduce crime, reduce the fear of crime, and improve the quality of life. Built environment implementations of CPTED seek to dissuade offenders from committing crimes by manipulating the built environment in which those crimes proceed from or occur. The three most common built environment strategies are natural surveillance, natural access control and natural territorial reinforcement.
Natural surveillance and access control strategies limit the opportunity for crime. Territorial reinforcement promotes social control through a variety of measures.
Natural surveillance
Natural surveillance increases the threat of apprehension by taking steps to increase the perception that people can be seen. Natural surveillance occurs by designing the placement of physical features, activities and people in such a way as to maximize visibility and foster positive social interaction among legitimate users of private and public spacePublic space
A public space is a social space such as a town square that is open and accessible to all, regardless of gender, race, ethnicity, age or socio-economic level. One of the earliest examples of public spaces are commons. For example, no fees or paid tickets are required for entry, nor are the entrants...
. Potential offenders feel increased scrutiny and limitations on their escape routes.
- Design streets to increase pedestrian and bicycle traffic
- Place windowWindowA window is a transparent or translucent opening in a wall or door that allows the passage of light and, if not closed or sealed, air and sound. Windows are usually glazed or covered in some other transparent or translucent material like float glass. Windows are held in place by frames, which...
s overlooking sidewalkSidewalkA sidewalk, or pavement, footpath, footway, and sometimes platform, is a path along the side of a road. A sidewalk may accommodate moderate changes in grade and is normally separated from the vehicular section by a curb...
s and parking lots. - Leave window shades open.
- Use passing vehicular traffic as a surveillance asset.
- Create landscape designLandscape designLandscape design is an independent profession and a design and art tradition, practised by landscape designers, combining nature and culture. In contemporary practice landscape design bridges between landscape architecture and garden design.-Design scope:...
s that provide surveillance, especially in proximity to designated points of entry and opportunistic points of entry. - Use the shortest, least sight-limiting fenceFenceA fence is a freestanding structure designed to restrict or prevent movement across a boundary. It is generally distinguished from a wall by the lightness of its construction: a wall is usually restricted to such barriers made from solid brick or concrete, blocking vision as well as passage .Fences...
appropriate for the situation. - Use transparent weather vestibulesVestibule (architecture)A vestibule is a lobby, entrance hall, or passage between the entrance and the interior of a building.The same term can apply to structures in modern or ancient roman architecture. In modern architecture vestibule typically refers to a small room or hall between an entrance and the interior of...
at building entrances. - When creating lighting designArchitectural lighting designArchitectural lighting design is a field within architecture and architectural engineering that concerns itself primarily with the illumination of buildings. The objective of architectural lighting design is to obtain sufficient light for the purposes of the building, balancing factors of initial...
, avoid poorly placed lights that create blind-spots for potential observers and miss critical areas. Ensure potential problem areas are well lit: pathways, stairs, entrances/exits, parking areas, ATMs, phone kiosks, mailboxes, bus stops, children's play areas, recreation areas, pools, laundry rooms, storage areas, dumpster and recycling areas, etc. - Avoid too-bright security lightingSecurity lightingIn the field of physical security, security lighting is often used as a preventative and corrective measure against intrusions or other criminal activity on a physical piece of property. Security lighting may be provided to aid in the detection of intruders, to deter intruders, or in some cases...
that creates blinding glare and/or deep shadows, hindering the view for potential observers. Eyes adapt to night lighting and have trouble adjusting to severe lighting disparities. Using lower intensity lights often requires more fixtures. - Use shielded or cut-off luminaires to control glare.
- Place lighting along pathways and other pedestrian-use areas at proper heights for lighting the faces of the people in the space (and to identify the faces of potential attackers).
Natural surveillance measures can be complemented by mechanical and organizational measures. For example, closed-circuit television
Closed-circuit television
Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....
(CCTV) cameras can be added in areas where window surveillance is unavailable.
Natural access control
Natural access control limits the opportunity for crime by taking steps to clearly differentiate between public space and private space. By selectively placing entrances and exits, fencing, lighting and landscape to limit access or control flow, natural access control occurs.- Use a single, clearly identifiable, point of entry
- Use structures to divert persons to reception areas
- Incorporate mazeMazeA maze is a tour puzzle in the form of a complex branching passage through which the solver must find a route. In everyday speech, both maze and labyrinth denote a complex and confusing series of pathways, but technically the maze is distinguished from the labyrinth, as the labyrinth has a single...
entrances in public restrooms. This avoids the isolation that is produced by an anteroom or double door entry system - Use low, thorny bushes beneath ground level windows. Use rambling or climbing thorny plants next to fences to discourage intrusion.
- Eliminate design features that provide access to roofs or upper levels
- In the front yard, use waist-level, picket-type fencing along residential property lines to control access, encourage surveillance.
- Use a locking gate between front and backyards.
- Use shoulder-level, open-type fencing along lateral residential property lines between side yards and extending to between back yards. They should be sufficiently unencumbered with landscaping to promote social interaction between neighbors.
- Use substantial, high, closed fencing (for example, masonry) between a backyard and a public alley.
Natural access control is used to complement mechanical and operational access control measures, such as target hardening
Target hardening
Target hardening is a term chiefly used by police officers and those working in security, referring to the strengthening of the security of building in order to reduce or minimising the risk of attack or theft...
.
Natural territorial reinforcement
Territorial reinforcement promotes social control through increased definition of space and improved proprietary concern.An environment designed to clearly delineate private space does two things. First, it creates a sense of ownership. Owners have a vested interest and are more likely to challenge intruders or report them to the police. Second, the sense of owned space creates an environment where "strangers" or "intruders" stand out and are more easily identified. By using buildings, fences, pavement, signs, lighting and landscape to express ownership and define public, semi-public and private space, natural territorial reinforcement occurs. Additionally, these objectives can be achieved by assignment of space to designated users in previously unassigned locations.
- Maintained premises and landscaping such that it communicates an alert and active presence occupying the space.
- Provide trees in residential areas. Research results indicate that, contrary to traditional views within the law enforcement community, outdoor residential spaces with more trees are seen as significantly more attractive, more safe, and more likely to be used than similar spaces without trees.
- Restrict private activities to defined private areas.
- Display security system signage at access points.
- Avoid cyclone fencing and razor-wire fence topping, as it communicates the absence of a physical presence and a reduced risk of being detected.
- Placing amenities such as seating or refreshments in common areas in a commercial or institutional setting helps to attract larger numbers of desired users.
- Scheduling activities in common areas increases proper use, attracts more people and increases the perception that these areas are controlled.
Territorial reinforcement measures make the normal user feel safe and make the potential offender aware of a substantial risk of apprehension or scrutiny.
Other CPTED Elements
Maintenance and activity support aspects of CPTED were touched upon in the preceding, but are often treated separately because they are not physical design elements within the built environment.Maintenance
Maintenance is an expression of ownership of property. Deterioration indicates less control by the intended users of a site and indicate a greater tolerance of disorder. The Broken Windows Theory is a valuable tool in understanding the importance of maintenance in deterring crime. Broken Windows theory proponents support a zero toleranceZero tolerance
Zero tolerance imposes automatic punishment for infractions of a stated rule, with the intention of eliminating undesirable conduct. Zero-tolerance policies forbid persons in positions of authority from exercising discretion or changing punishments to fit the circumstances subjectively; they are...
approach to property maintenance, observing that the presence of a broken window will entice vandals to break more windows in the vicinity. The sooner broken windows are fixed, the less likely it is that such vandalism will occur in the future.
Activity Support
Activity support increases the use of a built environment for safe activities with the intent of increasing the risk of detection of criminal and undesirable activities. Natural surveillance by the intended users is casual and there is no specific plan for people to watch out for criminal activity.Effectiveness and criticism
CPTED strategies are most successful when they inconvenience the end user the least and when the CPTED design process relies upon the combined efforts of environmental designEnvironmental design
Environmental design is the process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products...
ers, land managers, community activists, and law enforcement professionals.
In terms of effectiveness, a more accurate title for the strategy would be crime deterrence through environmental design. Research demonstrates that offenders cannot be literally prevented from committing crimes by using CPTED. CPTED relies upon changes to the physical environment that will cause an offender to make certain behavioral decisions. Those changes are crafted so as to encourage behavior, and thus they deter rather than conclusively "prevent" behavior.
Beyond the attraction of being cost effective in lowering the incidence of crime, CPTED typically reduces the overall costs of preventing crime. Retrofitting an existing environment to meet CPTED can sometimes be costly, but when incorporated in the original design phase of facility planning, cost of designing to CPTED principles are often lower than with traditional approaches. Operational costs are often lower also, as CPTED lighting designs can significantly lower energy use. Adding to the attraction of CPTED is that it lowers liability.
The area of liability has led to the questioning of how much crime prevention is really necessary for a given place. It has been mooted that a risk management approach might be superior to a fear-driven one. The question is, "does a community give up too much freedom, usually in terms of movement and assembly, to be free from fear of crime?" This was a question that was not widely asked in the 1990s; note the rise around the world of gated communities and the use of CCTV
Closed-circuit television
Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....
in public spaces.
Four obstacles to adopting CPTED
There are four primary obstacles to the adoption of CPTED.First is a lack of knowledge of CPTED by environmental designers, land managers, and individual community members. For this reason, allocating substantial resources to community educational programs are often required.
The second major obstacle is resistance to change. Many specifically resist the type of cooperative planning that is required to use CPTED. Beyond that, skeptics reject the research and historic precedents that support the validity of CPTED concepts.
The third obstacle is the perception that CPTED claims to be a panacea for crime
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...
that will be used to displace other more traditional approaches rather than a small, but important, complementary tool in deterring offender behavior.
The fourth obstacle is that many existing built areas were not designed with CPTED in mind, and modification would be expensive, politically difficult, or require significant changes in some areas of the existing built environment.
External links
- International CPTED Association
- European Designing Out Crime Association
- Stichting Veilig Ontwerp en Beheer (the Netherlands)
- California Designing Out Crime Association
- Crime prevention and the built environment.
- Washington State University CPTED Annotated Bibliography. Url last accessed May 6, 2006.
- Oscar Newman, Creating Defensible Space (pdf) (Washington, D.C.: U.S. Department of Housing and Urban Development, Office of Policy Development and Research, 1996). Url last accessed May 6, 2006.
- CPTED Crime Prevention Guide. CPTED Handbook for Architects and Urban Planners.
- CPTED LinkedIn Discussion Group