areas, when IDS sensors are desired to increase the detection capability of
the security force.
Taut-wire sensored fences will be 7 feet (2.1 m) high and have a
31-inch (787.4-mm) double outrigger equipped with sensor devices. The sensor
system shall consist of horizontal barbed wire spaced approximately 4 inches
(101.6 mm) apart and connected to a central detection device tensioned between
two anchor devices. Before designing taut-wire sensored fences, Naval
Electronic Systems Engineering Center (NAVELEXCEN) should be contacted for the
latest installation specifications.
Special Requirements. In order to maintain optimal performance
for electromechanical fence sensors, it is imperative that the chain-link
fence be well constructed with tight tensioning maintained throughout the
fence line. The fence construction must be adequate to support the added
weight of the IDS. This type of sensor requires frequent fence maintenance.
For additional details and information concerning fence design
requirements for specific fence IDS systems, contact NAVELEXCEN, Code 33, at
DSN 563-2030, commercial 803-745-4600 or write:
Naval Electronic Systems Engineering Center
4600 Mariott Drive
Charleston, SC 29418-6504
IDS Funding. MILCON funds cannot be used for design or
construction of IDS. MILCON projects may include fence IDS systems funded by
Penetration-Resistant Barriers. Recent terrorist incidents
involving the use of suicide-type crash entry forces the consideration of
vehicle barriers capable of stopping large vehicles traveling at high speed.
Crash tests of chain-link fences, similar to the chain-link fence
required by this handbook, allowed full penetration with no personnel injuries
of both a 1-1/2-ton (1360.7-kg) and 2-ton (1814.4-kg) vehicle traveling at 50
miles per hour (80.5 km per hour). An analysis of crash test data indicates
that, unless enhanced by the addition of cables, fences offer little
protection against penetration. Consequently, to meet a vehicle threat, fence
reinforcement measures may be required to maintain security of a restricted
area. Crash tests performed on a chain-link fence reinforced with a 3/4-inch
(19.1-mm) aircraft cable restricted penetration of a 2-ton (1814.4-kg) vehicle
traveling at 50 mph (80.5 km/h) to 26 feet (7.9 m).
When selecting barriers for penetration resistance, the designer
should choose active or passive barriers based on their capacity to stop the
threat vehicle at the maximum speed it could attain in its approach.