Crime Prevention Through Environmental Design
Crime prevention through environmental design (CPTED), is a multi-disciplinary approach to reducing crime and increasing perceived safety. CPTED relies upon the influence of offender behavior. It seeks to dissuade offenders from committing crimes by manipulating the physical environment in which those crimes occur. As a result, it relies upon an understanding of what about the environment influences offenders.
CPTED is most effective when involving environmental designers (e.g., architects, landscape architects), land managers (e.g., park managers), community action (e.g., neighborhood watch groups), and law enforcement. If any of the four defender groups are removed it is likely that a CPTED strategy will be less effective than it might otherwise be.
Coining the Phrase
CPTED, or "crime prevention through environmental design", is the brainchild of C. Ray Jeffery. The phrase began to gain acceptance after the publication of his 1971 book of the same name (Beverly Hills, CA: Sage). In recent years, it has become widely known, this due more to law enforcement's attempt to embrace it.
In hindsight, C. Ray Jeffery may sometimes wish he had opted to title his 1971 book "Crime deterrence through environmental design." It is clear from almost three decades of research that offenders can not with absolute certainty be prevented from committing crimes. This is especially true when one considers that CPTED relies upon changes to the environment that will cause an offender to make certain behavioral decisions. Those changes are crafted so as to encourage offenders, and thus they deter rather than conclusively "prevent" behavior.
Understanding the deterrence potential of CPTED can be related to the layers of a sandwich. The more layers of tasty ingredients that go into a sandwich, the more flavorful the end result. With CPTED, the more diverse layers of deterrence strategies that are employed the more likely that an offender will be persuaded to change his or her plans.
Defensible Space Relation and Difference
Defensible space came from the work of architect Oscar Newman. It focuses less on directly affecting offender decision making, and more on encouraging a defensive or protective mindset (and thus behavior) by the public. It assumes that changes in the physical environment can result in citizens becoming "defenders" as they become territorial, guarding places that matter to them. Defensible space remains a well known though not always well understood theory. It also continues to be at once supported by and contradicted by contemporary research.
Target Hardening Relation & Difference
While CPTED can include so-called target hardening, it is more than just that. Target hardening is best applied to a target that an offender attempts to enter (e.g., a building). It is less useful in open spaces such as parks where entry points are myriad. Target hardening is also an "overt" tactic. It does not place much emphasis on affecting offenders subtly or subconsciously. For example, an alarm system is often announced through stickers on windows or other common entry points. This explains to the offender that:
- A step has been taken to prevent the crime
- What that step was
- Potentially the degree of difficulty that defeating the step will entail (i.e., the quality of the alarm's manufacturer)
CPTED Is Not Meant Only for Police
One might argue that CPTED is not meant for police to so much as it is for environmental designers. The fact that police have knowledge of offenders and are relied upon to fight crime, coupled with the dearth of designers who understand or practice CPTED, has meant that law enforcement is usually the main (if not the only) group utilizing the approach.
Users of CPTED
CPTED is used by a variety of groups. Mostly they fall into one of four categories: environmental designers (e.g., architects, landscape architects), land managers (e.g., park managers), community action groups (e.g., neighborhood watch groups), and law enforcement groups (e.g., park rangers, metropolitan police). However each group is not equally equipped to apply CPTED. Instead, each has a unique knowledge base that makes it an important information source for creating effective CPTED strategies. Combined these groups can develop holistic plans that influence offender behavior yet do not neglect other considerations such as preservation of historic landscapes.
To have the Police Department evaluate your building plans, contact the Crime Prevention Unit at 972-941-2431. There is no charge for this evaluation.