CPTED consists of four key concepts:
- Natural Surveillance
- Natural Access Control
- Territorial Reinforcement
Natural surveillance is the placement of physical features, activities, and people to maximize visibility. It occurs when individuals can see from inside a home, office, business, or other designated area and people outside are able to see in. Consider how and where the structure is situated on its lot, and consider the orientation of windows, entrances, parking lots, etc., to provide maximum surveillance opportunities.
In commercial areas, CPTED recommends that business owners keep windows free of advertising signs and maintain landscaping, which allows for greater visibility into and out of retail space.
In parks, overlooks and shelters offer natural surveillance opportunities to many areas around the lake and the walking trails. Park visitors can be seen and can see others. Activities should be placed in an area to increase surveillance opportunities.
Inside multi-level buildings, having an open stairwell design creates opportunities for surveillance as well as creating the opportunity to be heard if assistance is needed.
Perpetrators of crime are attracted to areas with low visibility. This can be counteracted in the following ways:
- Lighting – Street lights should be well spaced and in working order; alleys and parking areas should also be lit. Lighting should reflect the intended hours of operation (lighting of playfields or structures in local parks may encourage afterhour criminal activity). Motion-sensing lights provide light when needed and lets trespassers know that they have been seen.
- Landscaping – Generally uniformly shaped sites are safer than irregularly shaped sites because there are fewer hiding places. Plants should follow the 3-8 rule; hedges no higher than three feet and tree limbs no lower than eight feet, especially around entryways and windows.
- Fencing – Fences should allow people to see in. Even if built for privacy, they shouldn't be too tall and should have some visibility.
- Windows – Windows that look onto streets and alleys are good natural surveillance, especially bay windows. These should not be blocked. Retirees, stay at home parents, and people working from home offices can provide good surveillance for the neighborhood during the day.
Natural Access Control
Natural access control is the the placement of walkway, fences, landscaping, and lighting to guide visitors to the entrance or exit. This principle helps deter access to a crime target or victim and creates a perception of risk to a perpetrator. However, this should also be balanced to avoid “user entrapment,” or not allowing for easy escape or police response. Generally crime perpetrators will avoid areas that only allow them one way to enter and exit, and that have high visibility or have a high volume of user traffic. This can be assured by:
- Putting vendors or shared public facilities near the entrance creates more traffic and more surveillance.
- A natural inclination is to place public restrooms away from centers of activity, but they can become dangerous if placed in an uninhabited area. Restrooms that are down long hallways or foyer entrances with closed doors are far away from the entrance of a park, or are not visible from the roadway can become problem areas.
- Homes with clearly visible and well lit front and back doors.
- Fences provide access control into a neighborhood and provides opportunities for Natural Surveillance due to its open design.
- Security guards monitor who comes and goes and where they go.
- Mechanical access control may be achieved through locking mechanisms such as a double cylinder deadbolt or a card reader system.
- Limit the number of access points into a building.
- Install mechanical or electronic locks.
Territoriality means showing that your community “owns” your neighborhood. While this includes removing graffiti and keeping buildings and yards maintained, it also refers to small personal touches. Creating flower gardens or boxes, seasonal decorations, signage, stone structure with property name, or maintaining plants in traffic circles seem simple, but sends a clear message that neighbors care and won’t tolerate crime. More complex design efforts can also make more dramatic changes. When planning for future growth, consider:
- Front porches and apartment balconies add to street surveillance.
- Traffic plans that consider the size of the neighborhood. Traffic circles or increasing the size of curbs can help calm traffic.
- Institutional architecture that respects the neighborhood identity and does not dwarf the current scale of the neighborhood.
- Clear transitions between private, semi-private, and public areas.
- Use signs that clearly display your address or business name on mail boxes and buildings, in parking areas, or along sidewalks.
Maintenance allows for the continued use of space for its intended purpose. It also serves as an additional expression of ownership.
- Uncut grass and weeds make a home or area look like it is not inhabited. It sends a message to criminals that no one cares and may be inviting to criminals. Plant new shrubs that will only grow to 2.5-3 feet tall. Trees should be trimmed up from the ground a minimum of four feet. This encourages plants with a natural growth habit that will not interfere with CPTED principles.
- Business, home, and apartment building owners that maintain their property make it inviting to potential customers. A manicured landscape, a clean and repaired building, proper lighting, and absence of trash will help to make potential customers feel safe, and thus make it likely that they will shop there as long as the property remains properly maintained.
- Use low maintenance or maintenance-free building products in your construction.
- Consider using long life bulbs for home applications to minimize frequently burned out exterior lighting.
- Install dusk to dawn sensors on lighting fixtures. Lighting is usually the least expensive crime prevention method.
- Remove inoperable vehicles, trash, and debris regularly.
Crime Prevention Through Environmental Design (CPTED...pronounced sep-ted) is the proper design and effective use of the built environment to reduce crime. CPTED looks at the entire neighborhood to identify areas that may potentially attract crime.