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 MIL-HDBK-1013/1A
Depending upon the assets, one or both of the above security operational
modes may be used. For example, security for arms, ammunition, and
explosives-type assets may require ingress prevention to assure that an
intruder never gains access to the weapons because of potential engagement
advantages against the guards offered by the weapons, or because of political
embarrassment, or other considerations. On the other hand, egress prevention
may be more appropriate for property assets when the objective is theft and
not sabotage. In this case allowance can be made in the timeline
calculations and design for intruder ingress and egress from the facility.
When both of the above operating modes are combined into one integrated
system, we say that the system has in-depth (i.e., backup) security
capability.
3.2.3
Security Denial/Containment Zones. In the most general case, the
spatial regions described as the "denial" and "containment" area or zone are
three-dimensional. Depending upon its physical extent, an exclusion or a
containment zone can be further characterized as either a "perimeter" or a
"point" zone. "Perimeter" zones tend to have large, extended volumes
characterized by a well-defined perimeter or boundary such as the exterior of
a large fenced-in site or a building. On the other hand, a "point" zone is
characterized by a very small or limited volume, e.g., a single vault in the
interior of a building or perhaps a secured cabinet containing classified
information. In this regard, one may have a building containing a security
system that relies on multiple defensive shells or layers of hardened
perimeter type barrier zones culminating in a single container point zone.
Figure 6 shows such a multilayered defensive configuration. The first, or
innermost, layer may be a container, a prefabricated magazine, a vault, or
simply a room containing the asset. These are followed by other interior
rooms, the exterior of the facility, and the site perimeter fence. Note that
although the outer perimeter fence shown in Figure 6 offers little
penetration delay (see par. 4.3.2.1), it does limit the amount of tools,
etc., that can be easily transported by the threat.
3.2.4
Balancing System Response and Intruder Timelines. In general, the
time for detecting, assessing, and responding must be less than, or at least
match, the intruder's time accounting for delays introduced by the barriers.
Depending on the design threat, the system design may have to be flexible
enough to handle anything from very "compressed" times for high-speed vehicle
intruders to more extended times for slower on-foot intruders. Also, the
timing and the performance of the real-time system elements must be designed
to complement each other. For example, if the responding function involves
an inherently long time (e.g., guards on foot), the detecting, assessing, and
delaying functions must be designed to detect, confirm, and delay the threat
in a time frame that matches these system delays.
It is also important to note that unless the threat is detected before, at,
or near the outside of the barrier, the delay stemming from the penetration
of the barrier cannot be accounted for when balancing against the guard force
response time. The guard force can only begin to respond after detection and
assessment. Consideration must be given to installing barriers so that they
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