Physical security describes security measures that are designed to deny
unauthorized access to facilities, equipment and resources, and to protect
personnel and property from damage or harm. Physical security involves the use
of multiple layers of interdependent systems which include CCTV surveillance,
security guards, protective barriers, locks, access control protocols, and
many other techniques. Overview
Physical security systems for protected facilities are generally intended to:
deter potential intruders; detect intrusions and monitor/record
intruders; and trigger appropriate incident responses.
It is up to security designers, architects and analysts to balance
security controls against risks, taking into account the costs of specifying,
developing, testing, implementing, using, managing, monitoring and
maintaining the controls, along with broader issues such as aesthetics, human
rights, health and safety, and societal norms or conventions. Physical access
security measures that are appropriate for a high security prison or a military
site may be inappropriate in an office, a home or a vehicle, although the
principles are similar. Elements and design
= Deterrence methods = The goal of deterrence methods is to
convince potential attackers that a successful attack is unlikely due to
strong defenses. The initial layer of security for a
campus, building, office, or other physical space uses crime prevention
through environmental design to deter threats. Some of the most common
examples are also the most basic: warning signs or window stickers,
fences, vehicle barriers, vehicle height-restrictors, restricted access
points, security lighting and trenches. Physical barriers
Physical barriers such as fences, walls, and vehicle barriers act as the
outermost layer of security. They serve to prevent, or at least delay, attacks,
and also act as a psychological deterrent by defining the perimeter of
the facility and making intrusions seem more difficult. Tall fencing, topped
with barbed wire, razor wire or metal spikes are often emplaced on the
perimeter of a property, generally with some type of signage that warns people
not to attempt to enter. However, in some facilities imposing perimeter
walls/fencing will not be possible or it may be aesthetically unacceptable; in
this case, the outer security perimeter will be defined as the wallsdoors of the
structure itself. Natural surveillance
Another major form of deterrence that can be incorporated into the design of
facilities is natural surveillance, whereby architects seek to build spaces
that are more open and visible to security personnel and authorized users,
so that intruders/attackers are unable to perform unauthorized activity without
being seen. An example would be decreasing the amount of dense, tall
vegetation in the landscaping so that attackers cannot conceal themselves
within it, or placing critical resources in areas where intruders would have to
cross over a wide, open space to reach them.
Security lighting Security lighting is another effective
form of deterrence. Intruders are less likely to enter well-lit areas for fear
of being seen. Doors, gates, and other entrances, in particular, should be well
lit to allow close observation of people entering and exiting. When lighting the
grounds of a facility, widely-distributed low-intensity
lighting is generally superior to small patches of high-intensity lighting,
because the latter can have a tendency to create blind spots for security
personnel and CCTV cameras. It is important to place lighting in a manner
that makes it difficult to tamper with, and to ensure that there is a backup
power supply so that security lights will not go out if the electricity is
cut off. = Intrusion detection and electronic
surveillance = Alarm systems and sensors
Alarm systems can be installed to alert security personnel when unauthorized
access is attempted. Alarm systems work in tandem with physical barriers,
mechanical systems, and security guards, serving to trigger a response when these
other forms of security have been breached. They consist of sensors
including motion sensors, contact sensors, and glass break detectors.
However, alarms are only useful if there is a prompt response when they are
triggered. In the reconnaissance phase prior to an actual attack, some
intruders will test the response time of security personnel to a deliberately
tripped alarm system. By measuring the length of time it takes for a security
team to arrive, the attacker can determine if an attack could succeed
before authorities arrive to neutralize the threat. Loud audible alarms can also
act as a psychological deterrent, by notifying intruders that their presence
has been detected. In some jurisdictions, law enforcement will not
respond to alarms from intrusion detection systems unless the activation
has been verified by an eyewitness or video. Policies like this one have been
created to combat the 94–99 percent rate of false alarm activation in the United
States. Video surveillance
Surveillance cameras can be a deterrent when placed in highly visible locations,
and are also useful for incident verification and historical analysis.
For example, if alarms are being generated and there is a camera in
place, the camera could be viewed to verify the alarms. In instances when an
attack has already occurred and a camera is in place at the point of attack, the
recorded video can be reviewed. Although the term closed-circuit television is
common, it is quickly becoming outdated as more video systems lose the closed
circuit for signal transmission and are instead transmitting on IP camera
networks. Video monitoring does not necessarily
guarantee that a human response is made to an intrusion. A human must be
monitoring the situation in real time in order to respond in a timely manner.
Otherwise, video monitoring is simply a means to gather evidence to be analyzed
at a later time. However, advances in information technology are reducing the
amount of work required for video monitoring, through automated video
analytics. = Access control =
Access control methods are used to monitor and control traffic through
specific access points and areas of the secure facility. This is done using a
variety of systems including CCTV surveillance, identification cards,
security guards, and electronic/mechanical control systems
such as locks, doors, turnstiles and gates.
Mechanical access control systems Mechanical access control systems
include turnstiles, gates, doors, and locks. Key control of the locks becomes
a problem with large user populations and any user turnover. Keys quickly
become unmanageable, often forcing the adoption of electronic access control.
Electronic access control systems Electronic access control manages large
user populations, controlling for user lifecycles times, dates, and individual
access points. For example a user's access rights could allow access from
0700h to 1900h Monday through Friday and expires in 90 days. These access control
systems are often interfaced with turnstiles for Entry control in
buildings to prevent unauthorized access. The use of turnstiles also
reduces the need for additional security personnel to monitor each individual
entering the building allowing faster throughput.
An additional sub-layer of mechanical/electronic access control
protection is reached by integrating a key management system to manage the
possession and usage of mechanical keys to locks or property within a building
or campus. Identification systems and access
policies Another form of access control includes
the use of policies, processes and procedures to manage the ingress into
the restricted area. An example of this is the deployment of security personnel
conducting checks for authorized entry at predetermined points of entry. This
form of access control is usually supplemented by the earlier forms of
access control, or simple devices such as physical passes.
= Security personnel = Security personnel play a central role
in all layers of security. All of the technological systems that are employed
to enhance physical security are useless without a security force that is trained
in their use and maintenance, and which knows how to properly respond to
breaches in security. Security personnel perform many functions: as patrols and
at checkpoints, to administer electronic access control, to respond to alarms,
and to monitor and analyze video. See also
Alarm management Biometrics
Biometric device Boundaries of Security Report
Burglar alarm Computer security
Door security Executive protection
Guard tour patrol system Information security
Logical security Physical Security Professional
School security Security engineering
Surveillance References