APPENDIX A: DEFENSIBLE SPACE AND CPTED: ORIGINS AND APPLICATION

A.1 INTRODUCTION AND BACKGROUND

The idea that environmental design - of sites and buildings - might 
play a role in crime reduction had its origins in Jane Jacobs's book, 
The Life and Death of Great American Cities (1961). Using personal 
observation and anecdote, she suggested that residential crime could be 
reduced by orienting buildings toward the street, clearly distinguishing 
public and private domains, and placing outdoor spaces in proximity to 
intensively used areas.

In 1971, architect Oscar Newman published a paper, "Architectural 
Design for Crime Prevention," and in 1973 published a book, Defensible 
Space, Crime Prevention through Urban Design. His studies of urban residential 
areas showed how physical design contributed to victimization by 
criminals. Newman explored the concepts of human territoriality, natural 
surveillance, and the modification of existing structures to effectively 
reduce crime, ideas that still form the foundation of building security design 
today. Newman's work became the foundation for what later became 
known as "Crime Prevention through Environmental Design" (CPTED).

The term "Crime Prevention through Environmental Design" had first 
appeared in a 1971 book by criminologist and sociologist C. Ray Jeffery, 
inspired by Jacobs's work. Jeffrey analyzed the causation of crime from 
an interdisciplinary approach, drawing from criminal law, sociology, psychology, 
the administration of justice, criminology, penology, and other 
fields. He also drew from relatively new fields at that time, including 
systems analysis, decision theory, environmentalism, behaviorism, and several 
models of crime control. 

Defensible space theory and CPTED were very influential in law enforcement 
and architectural communities, particularly in urban residential 
development and public housing design and retrofit; throughout the 
1980s, there were also a handful of architects, planners, and academics 
who advanced the field of CPTED, and it is to these pioneers that contemporary 
CPTED owes its existence. 

In this period of evolution, the CPTED methodology was organized to 
match the function of the crime area, similar to Newman's layering of 
space from private to public spaces. CPTED now defines three basic strategies 
for security design: natural access control, natural surveillance, and 
territorial reinforcement.



A.2 CPTED BASIC STRATEGIES

*  Natural access control consists of symbolic and real barriers that 
prevent the criminal from committing a crime. 
Natural access control strategies involve decreasing opportunities for 
crime by denying access to crime targets and creating a perception of 
risk in offenders. It is accomplished by the design of streets, sidewalks, 
building entrances, and neighborhood gateways to mark public 
routes, and by use of architectural and landscape structural elements 
to discourage access to private areas. 

*  Natural surveillance increases the awareness by residents or building 
users of who leaves and enters the property or buildings. 
Natural surveillance strategies are intended to make intruders easily 
observable. Features that maximize visibility of people, parking areas, 
and building entrances promote natural surveillance. Examples 
are doors and windows that look onto streets and parking areas, 
pedestrian friendly sidewalks and streets, front porches, and adequate 
nighttime lighting. 

*  Territorial reinforcement involves creating a sense of the users' 
proprietorship so that offenders perceive a territorial influence. 
Territorial reinforcement strategies use physical design to create or 
extend a sphere of influence. Building users are trained to develop 
a sense of territorial control so that potential intruders will perceive 
this control and be discouraged from their criminal intentions. 
Features such as landscape planting, pavement surface design 
gateway treatments, and fences are used to define property lines and 
help distinguish private from public spaces to promote territorial 
reinforcement. 

CPTED then divides each of these three strategies into response 
classifications:

*  Natural concepts use design tools for avoiding user conflicts and 
providing clear circulation paths. 
These concepts employ physical and spatial features, such as site and 
architectural elements, to ensure that a setting acts as a deterrent to 
crime while supporting the intended use of the space. Examples of 
natural features include landscaping, outdoor seating and planters, 
fences, gates, and walls. 

Sometimes referred to as "target hardening," mechanical measures 
emphasize hardware and technological systems, such as locks, security 
screens on windows, fencing and gating, key control systems, closed-
circuit television (CCTV), and other security technologies. Windows 
may have protective glazing that withstands blows without breaking. 
Doors and window hardware may have special material and mountings 
which make them hard to remove or tamper with. Walls, floors, or 
doors may be specially reinforced in high-security areas with materials 
that are difficult to penetrate.

*  Organizational concepts respond with management and personnel 
techniques. 

These concepts rely on people (individuals and vested groups) to 
provide surveillance and access control functions in the spaces they 
occupy at home or work. Organizational concepts may use concierges, 
security guards, designated guardians, residents in neighborhood 
watch programs, police officer patrols, and other individuals with the 
ability to observe, report, and intervene in undesirable or illegitimate 
actions. 



A.3 CPTED STRATEGIES FOR SITE PROTECTION

As examples of the application of CPTED principles and concepts, following 
are some of the CPTED strategies for site protection.

Examples of natural solutions:

*  Natural solutions designed to delay an intruder by creating barriers  such as walls, fences, water barriers, or landscapingm Natural solutions that allow for siting of buildings to reduce blind  spots and permit observation of movement by building users, such as  window placement, location of entrances, and walkwaysm Natural solutions that create boundaries with the building form or  landscaping to clearly delineate the public, semi-public, semi-private  and private spaces

Examples of mechanical solutions:

*  Mechanical solutions for the detection of an intrusion, through use of 
electronic or infrared sensingm Mechanical solutions that use technology to assist watching, such as 
CCTV and exterior site lightingm Mechanical solutions that define boundaries and territory with 
perimeter protection systemsm Devices that assist in the provision of access control at site entries
Examples of organizational solutions:

*  Solutions that provide for patrol and ability to respond, such as patrol 
routes, guardhouses and watch towers, or other locations.

*  Surveillance strategies that allow for unobstructed watch for intruders.

*  Solutions that use assigned or remote observers to detect, delay, and 
respond to intruders. Observers can be police, security guards, or 
trained building users. The building design may focus outward, for 
example, to allow observation of parking lots or playgrounds.

*  Solutions that provide the staff and/or users of the building with the 
means to distinguish outsiders or violators from legitimate site users. 
The site may have a vehicle control system that requires stickers, 
decals, ID cards, or access control badges.
Examples of territorial reinforcement solutions:


*  Strategies employ the building design and ability of users to challenge 
possible intruders and determine if they have a legitimate purpose.



A.4 CPTED TODAY

The basic CPTED planning concepts can often address vulnerability and 
risk in a more effective manner than many of the post 9/11 ad hoc measures, 
which heighten fear and unduly compromise the unique character 
of a place and a community.

It is necessary to ensure that there is a reasonable balance between planning 
for everyday crime prevention and planning to mitigate acts of 
terror. Acts of terrorism are infrequent events, and everyday crime levels 
may increase further if security measures are enacted that undermine the 
integrity of a community. Such measures are permanent street closures 
and rigid adherence to arbitrary permanent stand-off distance standards, 
etc. Well-planned temporary measures would allow protection from increased 
or reduced threats on an as-needed basis, which may occur rarely 
during the life of the site.

The CPTED security design process can be applied on a macro to micro 
scale. The three scales are building perimeter protection, in-site security 
design, and the building envelope and interior (which mirror the three 
layers of defense concept used in this publication). 

There is now an extensive literature on CPTED, and training courses 
are offered by some private consultants and by the International CPTED 
Association (ICA). A typical CPTED course is designed for a practitioner 
who will be involved in the application of proven crime prevention 
tactics to the built environment. Courses are relevant for architects, planners, 
community leaders, and police practitioners; they focus on the 
application of situational crime prevention measures to areas of our communities, 
with the goal of forming a total response to crime. 

Typical CPTED course topic areas are: 

*  Architectural terms and the process of architectural development 

*  Municipal and regional planning 

*  Analysis of crime potential within the design area 

*  How to develop plans to prevent environmentally induced crimes in 
practical applications of light and color 

*  Political analysis and development of CPTED codes and ordinances 

*  Security technology in support of natural surveillance and control 
A number of police forces in the United States have been trained in 
CPTED and apply the principles in their review of construction projects. 




A.5 CPTED SOURCES OF INFORMATION

Publications:

Publications relating to CPTED will be found in Appendix B, 
Bibliography

Web sites:

Defensible Space, nonprofit organization founded by Oscar Newman:
www.defensiblespace.com

International CPTED Association (ICA):
www.cpted.net

National Crime Prevention Institute:
www.louisville.edu/a-s/ja/ncpi

U.S. Department of State, Counterterrorism Office:
www.state.gov/s/ct

Security Design Coalition:
www.designingforsecurity.org