CPTED contends that architects, city planners, landscape and interior designers, and law enforcement can create a climate of safety in a community, right from the start by designing a physical environment that positively influences human behavior.
CPTED builds on four key strategies: territoriality, natural surveillance, activity support, and access control.
- Territoriality: People protect territory that they feel is their own and have a certain respect for the territory of others. Fences, pavement treatments, art, signs, good maintenance, and landscaping are some physical ways to express ownership. Identifying intruders is much easier in a well-defined space.
- Natural Surveillance: Criminals don't want to be seen. Placing physical features, activities, and people in ways that maximize the ability to see what's going on discourages crime. Barriers, such as bushes, sheds, or shadows, make it difficult to observe activity. Landscaping and lighting can be planned to promote natural surveillance from inside a home or building and from the outside by neighbors or people passing by. Maximizing the natural surveillance capability of such "gatekeepers" as parking lot attendants and hotel desk clerks is also important.
- Activity support: Encouraging legitimate activity in public spaces helps discourage crime. A basketball court in a public park or community center will provide recreation for youth, while making strangers more obvious and increasing active natural surveillance and the feeling of ownership. Any activity that gets people out and working together -- a clean-up day, a block party, a Neighborhood Watch group, a civic meeting -- helps prevent crime.
- Access control: Properly located entrances, exits, fencing, landscaping, and lighting can direct both foot and automobile traffic in ways that discourage crime. Access control can be as simple as a neighbor on the front porch or a front office. Other strategies include closing streets to through traffic or introducing neighborhood-based parking stickers.
These principles are blended in the planning or remodeling of public areas that range from parks and streets to office buildings and housing developments. Some jurisdictions have incorporated these principles into more comprehensive approaches.
The Three-D Approach to Planning CPTED
One way to involve CPTED principles in community development of renovation projects is through a three-step review process.
- Designation: What is the intended use of the area? What behavior is allowed?
- Definition: What are the physical limits of the area? What are the borders between this area and public spaces? Is it clear which activities are allowed where? What risks can be anticipated and planned for?
- Design: Does the physical environment support the intended use safely and efficiently?
Using the "Three Ds" to assess a space may reveal a conflict between the "Ds" -- a conflict that should result in a modification. If a space has no designated purpose, is poorly defined, or is not properly designed to support and control the intended function, that space may generate crime and fear unless modifications are made. Thus, the challenge is to design a parking deck or position public restrooms that are not only functional, but also maximize the personal safety of legitimate users.
Once the three Ds have been considered, the space is assessed according to how well it supports territoriality, natural surveillance, and natural access control. Natural access control and surveillance promote a greater sense of territoriality among users and a greater perception of risk in potential offenders. This may be accomplished with real barriers, such as fences, or with symbolic barriers, such as low-growing landscaping materials, elevation changes, or even changing the texture of the sidewalk.
CPTED Is Part of a Comprehensive Crime Prevention Program
CPTED works best when integrated into a comprehensive crime prevention program. Some crime prevention practitioners have misunderstood CPTED, often because of improper training, and so they have developed target programs that focus on locks, lighting, and alarms, but miss critical CPTED design elements.
The proper application of CPTED can help turn a crime-threatened neighborhood around. Several approaches can discourage undesirable vehicular traffic, including instituting turn- or time-related restrictions, narrowing traffic lanes, or installing small barriers ("nubs") at intersections to make the street look smaller. Residents who are encouraged to get involved through Neighborhood Watch begin to establish or reassert territorial control, thus also increasing natural access control and surveillance. This can be done in several ways, including improved lighting, proper landscaping, and signs to identify the neighborhood.