Environmental Engineering Reference
In-Depth Information
Numerous types of materials are used to construct fences, including chain
link, aluminum, wood, or wire. Some types of fences, such as split rails or
pickets, may not be appropriate for security purposes because they are tradi-
tionally low fences and are not physically strong; for example, the rails in a
split-rail fence may easily be broken. Potential intruders may be able to easily
defeat fences by jumping or climbing over them or by breaking through them.
Important security features of a fence include the height to which it can be
constructed, the strength of the material comprising the fence, the method
and strength of attaching the individual sections of the fence together at the
posts, and the ability of the fence to restrict the view of the assets inside the
fence. Additional considerations include the ease of installing the fence and
the ease of removing and reusing sections of the fence.
Some fences can include additional measures to delay, or even detect,
potential intruders. Such measures may include the addition of barbed wire,
razor wire, or other deterrents at the top of the fence. Barbed wire employed
at the base of a fence can also impede a would-be intruder's access to the
fence. Fences can be fitted with security cameras to provide visual surveil-
lance of the perimeter, and some facilities have installed motion sensors
along their fences to detect movement on the fence. Several manufacturers
have combined these multiple perimeter security features into one product
and offer alarms and other security features.
The correct implementation of a fence can make it a much more effective
security measure. Security experts recommend the following when a facility
constructs a fence:
• The fence should be at least 7 to 9 feet high.
• Any outriggers, such as bared wire, that are afixed on top of the
fence should be angled out and away from the facility, not in toward
the facility. This will make climbing the fence more difficult and will
prevent the placement of ladders against the fence.
• Other types of hardware that can increase the security of the fence
include installing concertina wire along the fence (this can be done
in front of the fence or at the top of the fence) or adding intrusion
sensors, camera, or other hardware to the fence.
• All undergrowth should be cleared for several feet (typically 6 feet)
on both sides of the fence. This will allow for a clearer view of the
fence by any patrols in the area.
• Any trees with limbs or branches hanging over the fence should be
trimmed so intruders cannot use them to go over the fence. Also, it
should be noted that fallen trees can damage fences, so management
of trees around the fence can be important. This can be especially
important in areas where the fence runs through a remote area.
• Fences that do not block the view from outside the fence allow
patrols to see inside the fence without having to enter the facility.
