Crime Prevention Through Environmental Design, or CPTED (pronounced sep-ted), is defined as the proper design and effective use of the built environment that can lead to a reduction in the fear and incidence of crime, and an improvement of the quality of life.
There are three basic and overlapping principles in the CPTED concept.
We need to create environments where there are plenty of opportunities for people engaged in their normal behavior to observe the space around them. By designing the placement of physical features, activities and people in such a way to maximize visibility, natural surveillance occurs.
Natural Access Control
Most criminal intruders will try to find a way into an area where they will not be easily observed. Limiting access and increasing natural surveillance keeps them out altogether or marks them as an intruder. By selectively placing entrances and exits, fencing, lighting and landscape to control the flow of or limit access, natural access control occurs.
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 owners and define public, semi-public and private space, natural territorial reinforcement occurs.
Why the emphasis on "Natural?"
Historically, the emphasis has been on the target hardening approach to crime prevention. Relying on mechanical (locks, security systems, alarms, monitoring equipment, etc.) and organized (security patrols, law enforcement, etc.) crime prevention strategies as a means to make the target harder to get into and can create a fortress effect and "feel" unsafe. This traditional approach tends to overlook the opportunity for natural access control and surveillance.
The CPTED theory advocates that all possibilities for natural crime prevention is exhausted prior to the involvement of the mechanical and organized strategies. The CPTED approach is much more user friendly and customer service oriented than the traditional target hardening approach.
CPTED involves the design of the physical space in the context of the bona fide user of the space, the normal and expected use of that space, and the predictable behavior of users and non-users. CPTED emphasizes the connection between the functional objective of space utilization and behavior management. By using the "Three D's" as a guide, space may be evaluated by asking the following types of questions:
- What is the designated purpose of this space?
- For what purpose was it originally intended?
- How well does the space support its current use or its intended use?
- Is there a conflict?
- How is space defined?
- Is it clear who owns it?
- Where are its borders?
- Are there social or cultural definitions that affect how space is used?
- Are the legal or administrative rules clearly set out and reinforced in policy?
- Are there signs?
- Is there conflict or confusion between purpose and definition?
- How well does the physical design support the intended function?
- How well does the physical design support the desired or accepted behaviors?
- Does the physical design conflict with or impede the productive use of the space or the proper functioning of the intended human activity?
- Is there confusion or conflict in the manner in which physical design is intended to control behavior?
Once these questions have been asked, the information received may be used as a means of guiding decisions about the use of human space. The proper functions have to be matched with space that can support them. The design has to assure that the intended activity can function well and it has to directly support the control of behavior.