be the shortest distance between the fence and the building measured using
the preliminary site layout plan developed under Element <2>. This ingress
time should be inserted in the appropriate slot under Column E of the
"Facility Exterior" portion of the applicable worksheet (Appendix A).
<29> Estimate fence-to-building ingress plus egress time. If
threat containment rather than exclusion is permitted, both the site-related
threat ingress and egress time can be accounted for. The on-foot ingress
time can be estimated using Figure 8. The egress time may be shorter or
longer than shown in Figure 8 depending on the weight or volume of the assets
being stolen. In both cases, the distance used should be the shortest
between the fence and the building established using the preliminary site
layout plan developed under Element <2>. Insert the ingress and egress times
in the appropriate slots under Column E of the "Facility Exterior" portion of
the applicable worksheet (Appendix A).
<30> Site has an exterior fence CCTV or tower guard? If the site
already has, or is required to have, an exterior fence CCTV or tower guard,
the flow chart branches to Element <34>, otherwise to Element <31>.
<31> Building to have a CCTV or on-site guard? If the designer has
reached this point, no CCTV or tower guards are required along the perimeter
fences for threat assessment. This function must occur at the building. At
this point a decision is required if threat assessment is to be accomplished
by dispatching a guard to the building or by using CCTV. The advantage of
using CCTV is that real-time assessment is possible from a remote monitoring
location, reducing the overall security system response timeline (see Figure
5). The disadvantage is the cost for purchasing, installing and maintaining
the system. Paragraph 5.3.5 summarizes CCTV options referencing appropriate
sources for details. If a CCTV is to be provided, the flow chart branches to
Element <34>, otherwise to Element <32>.
<32> Initial response includes reaction force? If the designer has
reached this point, the use of CCTV for threat assessment is not an option
and one must rely on a guard responding to the location of an alarm. If the
guard operating procedures allow for an on-site guard, or if the initial
response includes the full reaction force to engage and counter the threat,
the flow chart branches to Element <34>, otherwise to Element <33>.
<33> Double guard response time. If the designer has reached this
point, the dispatch of a guard is required for threat assessment before the
full reaction force. The designer should double the "Minimum Delay Time
Required to Match Guard Response" in Row (4) of the worksheet (Appendix A).
<34> Threat exclusion or confinement. If the threat is to be
excluded from the critical asset, one can only account for the ingress time
from the building exterior to the innermost shell (Figure 6) containing the
asset. On the other hand if the threat is to be contained within the
building, the egress time out may also be accounted for. In the case of