A security fence serves the following functions:
a) Restricted area boundary definition. Fences are used
to define the outermost boundary of a restricted area to deter accidental or
casual intruders from entering.
b) Surveillance region definition.
When required by a
DoD regulation, fences are used to define the surveillance region of an
exterior intrusion detection system (IDS or guards), an assessment system
(CCTV or guards), and associated exterior security lights.
c) Timeline initiation. In conjunction with any required
exterior perimeter guards or IDS system, fences cause a dedicated
forced-entry threat to initiate an overt action which starts the timeline for
the security system response.
d) Traffic control. Fences are used to channel and
control the flow of personnel and vehicles through designated entries into
Security Fence Types
a) Design options. Table 6 and Figure 14 present examples
of security fence configuration. In general, security fences are made of
either taut wire or standard chain link metal fabric with various
enhancements (Table 6). Fence enhancements include different configurations
of barbed wire outriggers (Figure 14). Personnel and vehicle fence gates are
addressed under entry control in par. 4.4.4. The reader is referred to
MIL-HDBK 1013/10 for details on fence design options.
b) Delay times. In general, fences (both with and without
enhancements) offer delays of less than 1 minute against low-level threats to
as little as 3 to 8 seconds against trained and dedicated high-level intruder
teams. The height [up to 8 feet (2.4 m)] of the fence, or the degree of
enhancements used (Figure 14) make little difference on this time. In
general, fence material can be easily cut, or climbed over. This includes
barbed wire which can easily be climbed over with the aid of blankets, etc.
However, fences do offer some advantage in limiting the amount of tools,
etc., that an intruder can readily carry into the site.
c) Fence selection including minimum requirements. In
general, the delay time offered is not a significant factor in selecting a
fence. A simple fence without enhancements will be adequate in most cases to
define the site boundary, deter the casual intruder, or support an exterior
IDS system. The use of fence enhancements offers the increased appearance of
impregnability, but this should be weighted in terms of the increased
material and maintenance costs. Specific minimum fencing requirements that
are prescribed by military regulation include (see also MIL-HDBK 1013/10):