Section 2 – Design Strategies Crime Prevention Through Environmental Design Principles – January 2002 Page 5

2. Design Strategies

There are three overlapping CPTED design strategies.

They are:� natural surveillance� natural access control, and,� territorial reinforcement.

Natural surveillance is a design strategy that is directed at keeping intruders under observation.

Natural access control is a design strategy that is directed at decreasing crime opportunity. Theprimary thrust of an access control strategy is to deny access to a crime target and to create aperception of risk in offenders.

Territorial reinforcement is an “umbrella” design strategy that realizes that physical design cancreate or extend a sphere of influence so that users of a property develop a sense ofproprietorship over it. Territorial strategies will often embody natural surveillance and naturalaccess control strategies.

The conceptual thrust of the CPTED program is towards the exploitation of “natural” forms ofsurveillance and access control. The term “natural” when referring to natural surveillance andaccess control, refers to deriving surveillance and access control as a result of the routine use andenjoyment of the property.

Examples of “natural” forms of surveillance include the strategic use and placement of parkbenches, windows and lobbies. Examples of “natural” forms of access control include thestrategic use of distance (e.g. lawns, flooring) and/or topographical features (e.g. creeks,sidewalks) to direct activity or create a buffer between potentially conflicting activities.

Mechanical Forms of Surveillance & Access Control

Other forms of surveillance and access control often used by designers include mechanical formssuch as lighting, fencing or gating.

Territorial Reinforcement

Territorial reinforcement is an expression of proprietorship. For example, a clean, well lit attractivestore will present behaviourial and environmental cues which tells the “normal user” that they aresafe and only accepted behaviours will be tolerated. The same cues have an adverse effect on“abnormal users”. The design of space and the way people are behaving will give the impressionthat the abnormal user will be observed, stopped or apprehended.

Territorial reinforcement, together with natural surveillance and access control, promotes moreresponsiveness by users in protecting their territory.

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Principle:To develop a design that functions well and supports the intended human behaviour.

Section 2.1 Natural SurveillanceIssues Objectives

� Does the design allow us to observe? (a) Design space to facilitate observation byincreasing “visual permeability” i.e. theability to see what is ahead and around.Measure the need for privacy and/orlimited sightlines against the need forpersonal safety. See Photos 1 and 2....

� Is this level responsive to the needs forobservation?

(b) Place vulnerable activities, such as cashhandling/child care and others, in placesthat can be naturally, well-monitored.Develop potential for “eyes on the street”by strategically aligning windows, workstations and other activity generatorstowards these areas of “vulnerable activity”.See Photo 3.

� Has the need for observation beencarried consistently throughout theproject?

(c) Take special care to ensure that each phaseof the project enhances and complementsnatural surveillance opportunities createdin the design phase. This is particularlycritical with respect to the landscaping andlighting phases.

Photo 1: These houses have been strategically designed and placed toPhoto 1: These houses have been strategically designed and placed toPhoto 1: These houses have been strategically designed and placed toPhoto 1: These houses have been strategically designed and placed tomaximize observation to the entrance of the streets and themaximize observation to the entrance of the streets and themaximize observation to the entrance of the streets and themaximize observation to the entrance of the streets and theneighbouring homes.neighbouring homes.neighbouring homes.neighbouring homes.

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Photo 2: Windows have been incorporated into the interior of thePhoto 2: Windows have been incorporated into the interior of thePhoto 2: Windows have been incorporated into the interior of thePhoto 2: Windows have been incorporated into the interior of theparking garage electrical room, which lessens criminal opportunity byparking garage electrical room, which lessens criminal opportunity byparking garage electrical room, which lessens criminal opportunity byparking garage electrical room, which lessens criminal opportunity byproviding for natural surveillance.providing for natural surveillance.providing for natural surveillance.providing for natural surveillance.

Photo 3: Windows have been placed so that this children’s playgroundPhoto 3: Windows have been placed so that this children’s playgroundPhoto 3: Windows have been placed so that this children’s playgroundPhoto 3: Windows have been placed so that this children’s playgroundcan be monitored from the adjacent laundry room.can be monitored from the adjacent laundry room.can be monitored from the adjacent laundry room.can be monitored from the adjacent laundry room.

Section 2 – Design Strategies Crime Prevention Through Environmental Design Principles – January 2002 Page 8

Section 2.2 Natural Access ControlIssues Guidelines

� Does the design decrease criminalopportunity by effectively guiding andinfluencing movement?

(a) Provide for “eyes on the street” through thestrategic placement of entrances, windows,etc.

Direct normal access to observable areasand prevent access to unobservable areas.Design space to provide people with asense of direction while giving them somenatural indication as to where they are andare not allowed (refer to Definitionguidelines – Sec. 3.2) See Photo 4.

� Will safety be compromised by limitingaccess?

(b) Provide a limited number of access routeswhile allowing users some flexibility inmovement.

� Does the design develop natural accesscontrol opportunities withoutconsidering their impact on naturalsurveillance?

(c) Take special care to ensure that naturalaccess control opportunities enhance andcomplement natural surveillance objectives.

Photo 4: Multiple Entrances into this parking lot were replaced by aPhoto 4: Multiple Entrances into this parking lot were replaced by aPhoto 4: Multiple Entrances into this parking lot were replaced by aPhoto 4: Multiple Entrances into this parking lot were replaced by asingle, well observed entrance that includes a fence and control gate.single, well observed entrance that includes a fence and control gate.single, well observed entrance that includes a fence and control gate.single, well observed entrance that includes a fence and control gate.

Section 2 – Design Strategies Crime Prevention Through Environmental Design Principles – January 2002 Page 9

Section 2.3 Territorial ReinforcementIssues Objectives

� Does the design act as a catalyst fornatural surveillance and access controlopportunities?

(a) Enhance the feeling of legitimateownership by reinforcing existing naturalsurveillance and natural access controlstrategies with symbolic or psychologicalbarriers. Accomplish this by demonstratingthe transition between public, semi-publicand private space so that unwantedintrusion elicits a protective response thatoffenders will perceive. This is often easilyaccomplished with the strategic use ofbollards and signs. See Photo 5.

� Does the design create ambiguousspaces?

(b) Minimize the creation of ambiguous spaces(a space is ambiguous when it lacks anysort of clue as to what it is for, and who it isfor). Accomplish this by identifyingpotential “leftover spaces”, for instance thearea between the aboveground portion ofa building’s underground parking lot andits property line. Then take some positiveaction to develop this space so that users ofthe property take responsibility for it.

� Will the design create heavy orunreasonable maintenance demands?

(c) Design space to allow for its continued useand intended purpose. Create durableenvironments that limit the need formaintenance especially where it affectsnatural surveillance and access control.

Photo 5: Concrete bollards have been used to define the transitionfrom public to private space.