Traditionally, crime prevention was emphasized with organized and mechanical strategies. Organized strategies are considered the use of people like law enforcement, patrol, neighborhood watch teams and security personnel to control crime. The mechanical strategies traditionally are target hardening strategies. This includes anything that is electronic and mechanical like alarm systems, camera systems, locks to deny access to a potential offender. However, this traditional approach overlooks how the environment can provide opportunities. CPTED on the other hand, uses organized and mechanical approaches as a secondary model. Its primary focus is on natural strategies and design aspects. A natural approach enhances safety without creating a prison like environment while reinforcing an atmosphere of comfort.
CPTED is comprised of three categories of actors. These actors are people who relate one way or another to a particular location. These actors involve normal users, abnormal users, and observers (Paxton). The sole purpose of CPTED is to design an environment where normal users can use a space as desired while abnormal users are influenced to move passed it (Paxton). This design also makes it easier for observers to take note on what is going on in the location and report anything suspicious or criminal (Paxton).
There are four basic overlapping principles of CPTED as shown in the previous example: natural surveillance (will I be seen), natural access control (can I get in and out), territoriality (does anyone care what happens here), and maintenance.
The second principle is natural access control which is a strategy used to control access to an area, deny access, and to create a perception of risk in criminals.
"Control access by creating both real and perceptual barriers to entry and movement. The environment must offer cues about who belongs in a place, when they are supposed to be there, where they are allowed to be while they are there, what they should be doing, and how long they should stay"(POPCENTER).
Barriers identify property lines (public to private), prevent trespassers, outline boundaries, add visual appeal and enhance access control. Thus, natural access control is accomplished by using fences, gates, signage, pavements, lighting and landscaping. Fences and gates are real barriers where signs, lighting, landscaping and pavements are perceptual barriers. Both types of barriers protect the outside of a house/business by guaranteeing that unauthorized persons don't get inside to cause harm and create a perception among offenders that there is a risk in selecting the target.
An example of a real barrier would be having a fence around an entire house. This fence sends a message to abnormal users, that the property is restricted and you cannot enter. It also shows territoriality or ownership that the people who live there care. Mechanical devices of access such as locks, cameras, and alarms are secondary parts of natural access control methods but used if needed. Limiting access is another way of controlling access to various areas with real barriers. Gates can limit the point of entry into a home or a building. By strategically placing entrances, exits, gates, and fencing, to control or limit access, natural access control occurs. In the example from earlier, multiple entrances into the park were replaced by a single entrance that includes fencing and a gate. Real barriers would great in private zones like neighborhoods where residents themselves can make the changes needed to keep their property safe.
On the other hand, when moving outside private property to public (streets, sidewalks) or semi-public spaces (theatres), utilizing access control devices needs more care. Properly located entrances, exits, fencing, landscaping and lighting can subtly direct both foot and vehicular traffic in ways that decreases criminal opportunities. This is where perceptual barriers can be used to achieve the objective of access control. These barriers include: signs, paths, walkways, paving surfaces, or anything that announces the uniqueness of an area. All of these barriers guide movement throughout an area. Signs direct movement and identify the intended users. So if a sign says employees only then abnormal uses will be easy to recognize because they do not belong. Public buildings should have paths going in particular direction of point A to B that way people are not wondering around and come upon an opportunity to commit a crime. The best example of perceptual barriers is Disney Land. They have colored roads directing you from one ride to another ride or to the restroom and food court. There is a path/walway for wherever you need to be. This is why Disney has a low crime rate. People are not wondering around because everyone is on path to the next thing. The idea behind a psychological barrier is that if a target seems difficult, it will become unattractive to potential criminals.
When contemplating how you want to control access in an area, one can't forget about the importance of surveillance. These strategies overlap so you can't think about one without the other. These two concepts can occasionally conflict with one another. For example, Even a simple low-level hedge or row of thorny bushes around a garden can be effective in keeping people from entering. In addition, fencing defines boundary lines that deter and delay intruders. When installing a fence, it should be a type of fencing where you can see through it. Therefore, you are preventing access control by having a fence but also keeping up with natural surveillance. In addition, the height of the fence can make a big difference as well. If you have the fence too high, you won't be able to see passed the fence to what is on the other side. Natural access control is a design strategy that is directed at decreasing crime opportunity.
The third principle is territorial reinforcement which uses design to show ownership.
"The design should provide cues about who belongs in a place and what they are allowed to do (POPCENTER)" The design features should clearly show uniqueness towards the home or building. Potential offenders will look at the territory and what they see will determine whether they will offend there or not. There are many communities where homes or apartments building or commercial business do not look like they are cared for. It could be because of the lack of maintenance on unkempt landscaping, peeling paint, or dark lighting. Whatever the reason, there is a clear message that this place is unimportant so you can do what you please. If the owner does not care why should outsiders? Abnormal uses take this as a huge opportunity to use these places for criminal activity. An example might be a local convenient store that has tons of graffiti all on the outside. The graffiti never gets taken care of so people think its ok to go inside and rob the store. On the other hand, if the store was clean and maintained it would present cues that normal users can come in and feel safe because they care. This in turn, gives an adverse effect to the abnormal users.
There are many things to consider when showing territorial reinforcement. First off, territorial methods include natural surveillance and natural access strategies. Each place should be unique in who belong there. We need to keep abnormal users out of these normal user areas. A company sign is something that shows uniqueness to a company as well as establishes ownership towards that building. Other reinforcements include: landscaping, flags, fences and pavements. All of these things express proprietorship and the vested interest the owner has over their property. As a result, offenders will realize that these people will more likely call the police on them rather than places with owners who don't care.
Ownership creates and environment where strangers or possible offenders stand out in the crowd. Using design structures like fences, signs, lighting, pavements treatments, maintenance and landscape you can not only show ownership but also define property lines and zones (public, private, semi-public). The use of front porches creates a transitional area between the street and home. Concrete bollards define the transition from public to private space. These zones are part of the use of defensible space which was brought to life by Oscar Newman in 1972. As described in Newman's book Design Guidelines for Creating Defensible Space, defensible space is "a residential environment whose physical characteristics-building layout and site plan-function to allow inhabitants themselves to become key agents in ensuring their security." As a result, identifying abnormal users such as burglars and trespassers is much easier because they do not belong.
All of these functions are not intended to stop anyone from actually intruding into a building or home. The point of territoriality is to convey a message to abnormal users that the property belongs to somebody and they should stay away. For buildings and businesses it sends a message of fear to offenders. Territorial reinforcement mixed with natural surveillance and access control, encourages more awareness by normal users in protecting their territory.
Maintenance is the last principle of CPTED which brings together all the other principles. It relates to the neighborhood's sense of admiration and territoriality. The more rundown an area, the more likely it is to attract unwelcome behaviors. This is because it seems like no one cares what goes on in that area. However, if the area is well taken care of it will demote the area as a target because of the fact that it shows people care what happens to their area. The maintenance and image of an area is the main influence on whether it will become targeted. This is also known as the Broken Windows theory by James Wilson and George Kelling. The physical appearance of a location can enhance or detract how its community sees it as well as outsiders. Moreover, its purpose is to heighten the visibility of natural surveillance resulting from landscaping overgrowth or defective lighting. Keeping trees and bushes trimmed from the near the windows will maintain visibility to be seen clearly. Make sure outdoor lighting is all working for the night time. Lastly, the upkeep of your access controls (no chipped paint on the fences) will show that the community and residents care about this area and what happens to it.
What makes a particular location prone to opportunities for crime? Why does this location jeopardize the safety of people? Why here? These are all questions crime prevention through environmental design asks when problem solving. For example, say there is a park in a nearby neighborhood that is known for drug sales, thefts and assaults. The park has four different entrances from the neighborhood, no fencing, low lighting, and no upkeep of shrubs and trees. What can CPTED bring to the table in response to this problem? The city installs a fence around the park to create a barrier between public and private property. A gate is also included beyond the fence with a camera attached for extra surveillance. They limit the amount of entrances into the park down to one which limits access control into the park. Lighting gets revamped with higher wattage bulbs. Lastly, a maintenance crew must come in a certain number of times a month to maintain the shrubs and trees to clean appearance. As a result to all of these changes, we now have better access control (limited entrances), better natural surveillance from residents (maintained shrubs to see in the park), and better territoriality towards to park to show it's a public area (fencing). The residents can now see into the park, report a crime when they see one and perpetrators will now think twice about committing crime for fear of being observed. Asking the question "why here?" shows that opportunities for crime can arise due to environmental conditions, the location and how that location is used.