Attachment_3_-_UFC_Design_Details.pdf

UFC 4-022-02

8 June 2009

Change 1, 9 August 2010

6-2.8 Tire Shredders.

6-2.8.1 Description.

Tire shredders can be either surface-mounted or imbedded, as shown in Figure 6-25.

These devices are normally used for traffic control purposes and are designed to slow or stop a vehicle by deflating their pneumatic tires. These units are available from a number of commercial manufacturers. Delta Scientific Corporation manufactures the unit shown in Figure 6-25. When a vehicle drives over the mechanism in the wrong direction, the spikes penetrate the tire casing, which quickly deflates the tires, making the vehicle difficult to operate for extended periods. These systems should not be considered vehicle barriers. Tire shredders are not recommended where vehicle traffic drives over these devices at speeds exceeding 5 mph. These systems may also not be effective against modern “run flat” tires, heavy-duty truck tires, or extra-wide tires that can bridge over two or more spikes. Tire shredders have a very limited capability to stop a vehicle.

Figure 6-25 Tire Shredders

6-2.8.2 Testing.

These systems have not been formally tested, and as indicated above are not considered a vehicle barrier.

6-2.9 Steel Cable Barriers.

6-2.9.1 Description.

UFC 4-022-03

1 October 2013 laid between poles with one roll on top of another or in a pyramid arrangement (minimum of 3 rolls). Concertina blades must have a minimum length of 1.2 inches (30.7 mm).

Barbed tape concertina as an expedient measure for short-term use, pending the erection of permanent fencing, can be non-reinforced. Reinforce all barbed tape concertina used for permanent security applications.

2-10 GROUNDING

Grounding and bonding of the perimeter systems must be in accordance with the National Electric Safety Code (NESC) - IEEE C2. Fences that are required to be grounded by NESC must be designed to limit touch, step, and transferred voltages in accordance with industry practices. IEEE Std 80™-2000 - IEEE Guide for Safety in AC Substation Grounding is one source that may be utilized to provide guidance in meeting these requirements.

The grounding connections must be made either to the grounding system of the enclosed equipment or to a separate ground.

1. Fences must be grounded at each side of a gate or other opening.

2. Gates must be bonded to the grounding conductor, jumper, or fence.

3. A buried bonding jumper must be used to bond across a gate or other opening in the fence, unless a nonconducting fence section is used.

4. If barbed wire strands are used above the fence fabric, the barbed wire strands must be bonded to the grounding conductor, jumper, or fence.

5. When fence posts are of conducting material, the grounding conductor must be connected to the fence post or posts, as required, with suitable connecting means

6. When fence posts are of nonconducting material, suitable bonding connection must be made to the fence mesh strands and the barbed wire strands at each grounding conductor point.

2-11 REINFORCEMENT FOR FENCING

Refer to UFC 4-022-01 and 4-022-02 for additional guidance and requirements (number and size of cables) on fence reinforcement for identified moving vehicle threat. For fabric type fences install fence reinforcement between fence fabric and fence post. For both fabric type and ornamental fences reinforcement must be installed on exterior side of fence post. If located in a corrosive environment, coated or sheathed cable may be used; however, the sheathing must be removed at the connections. See Figures 2-5/2- 6 and Appendix C for design details of fence reinforcement. See Appendix A for material specifications.

Figure 2-5 Steel Cable-Reinforced Chain Link Fence

2-11.1 Deadman Anchor

Reinforcing cables must be terminated to concrete deadman anchors. Anchors are to be placed at intervals of 200 feet (61 m) on the secure/protected side of the perimeter fencing. Offset deadman anchors from fence at the minimum distance required to avoid interference with post and to allow maintenance access to the turnbuckles, clamps, and other accessories.

The anchoring system: deadman dimensions or other anchoring systems and burial depth, eyebolt embedment depth, etc. must be designed for local soil conditions and the anticipated impact force established by the threat parameters defined in UFC 4-022-02.

See Appendix C for design details of deadman anchors.

2-11.1.1 Cable Connection

Eyebolts embedded in the concrete deadman anchors may have either a welded “T” or “L” end. The eyebolt can either be in-line with the attached cable or flush against the deadman surface. When used, eyebolts should be welded and galvanized to the anchor rods. The top side of the deadman can either be placed flush with or below the ground surface with the eye of the eyebolt above ground. Threaded rods may also be used as an alternative to the eye bolt when securing the cables to the deadman anchor.

When using threaded rods, the threaded rod and wire rope connection must be visible above ground like the eyebolt previously described.

Figure 2-6 and details in Appendix C show the deadman position using a cable clamp and turnbuckle to secure the cable rather than a swaged on clamp. This turnbuckle adds the advantage of being able to adjust the tension of the cable.

Figure 2-6: Deadman Anchor Detail

2-12 SPECIAL SECURITY FEATURES

2-12.1 Clear Zones

Clear zones are areas established around the fence to provide and unobstructed view to enhance detection and assessment around fences. When required, dimensions of clears zones vary depending on asset being protected and level of protection. For example, outer clear zones may be 30 feet (9 m) wide and inner clear zones may be 20 feet (6 m) wide. Consult with Service policies for assets being protected to determine if clear zones are required and what dimensions are required.

2-12.2 Double Fence Lines

Assets that require Electronic Security Systems (ESS) for perimeter security may require a double fence line. Perimeter ESS and double fence lines typically associated with assets that require a high level of protection for the force or covert entry tactic.

This system is intended to increase the probability of detection, decrease nuisance alarms, and prevent access to ESS. The typical configuration is outer clear zone, outer fence, isolation zone, inner fence, and inner clear zone. See Figure 2-7a/b below.

2-12.2.1 Outer Fence Line

Outer fence line acts to reduce the Nuisance Alarm Rate (NAR) by keeping animals, people, vehicles, and windblown debris out of the isolation zone. No sensors should be placed on the outer fence of a double fence line system. In some instances the outer fence line may define a protected or restricted area boundary. In the case where the

As shown in Figure 6-26, there are several configurations for steel cable barriers. Site requirements, configuration, and environment must be carefully considered prior to selecting a cable system for a particular application.

6-2.9.2 Testing.

Systems such as those shown in Figure 6-26 have not been formally tested. However, two 3/4-in. (1.9-cm) diameter cables attached to a 200-ft section of fence, minus fabric, with deadman anchors at both ends were tested with a 4,000-lb (1,818-kg) vehicle at 52 mph (84 kph). The vehicle was stopped within 13 ft (4 m) and then pushed back to the impact point. For additional considerations, details, and design guidance relating to the use of steel cables in fencing and gates, refer to UFC 4-022-03.

Change 1, 9 August 2010

Figure 6-26 Steel Cable Barriers

6-2.10 Steel Cable-Reinforced Chain Link Fencing.

6-2.10.1 Description.

Without some reinforcement, a standard chain-link fence can be penetrated easily by a light vehicle with little or no damage. However, standard fencing can be reinforced to provide a cost-effective method to protect against the threat of penetration by light vehicles, as in Figure 6-26 and Figure 6-27. Although no required pre-tension is

8’-6”

1’- 0-6

8’-6” specified for the cable, it is generally considered acceptable that it should be snug and not have significant sag. Routine (usually daily) perimeter inspection should include checking for visible sagging. At this time, there is no specific sag measurement benchmark, so checking for “visible” sag is a conservative approach. Regularly scheduled inspections should also check for corrosion of fittings, including the turnbuckles, anchor bolts, U-bolts, any swaged fittings, and cable clamps. Cable clamps should be inspected as well to insure no nuts have become loose. For additional considerations, details, and design guidance relating to the reinforcing of fencing and gates, refer to UFC 4-022-03.

Figure 6-27 Typical Steel Cable Reinforced Chain-Link Fencing

6-2.10.2 Testing.

Sandia National Laboratories tested a barrier consisting of a chain link fence reinforced with a 3/4-in. (1.9-cm) cable. In this test, a 3,350-lb (1,523-kg) vehicle traveling at 23.5 mph (38 kph) penetrated the barrier 7 ft (2.1 m). A 4,050-lb (1,841-kg) vehicle, traveling at 50.6 mph (82 kph), penetrated 26 ft (7.9 m), and the cable failed at the impact location. A test using two cables with no fabric was impacted by a 4,000-lb (1,814-kg) vehicle, traveling at 52 mph (84 kph), and the vehicle penetrated 13 ft (4 m) and then pushed back to the original fence line. Engineering analysis of various cable restraint configurations, using the BIRM computer model (PDC-TR90-2), is shown in Table 6-9.

Table 6-9 Performance of Cable Restraint Systems

Cable Barrier w/200-ft Anchorage Spacing

Kinetic Energy in ft-lbf x 1,000 (kgf-m)

Penetration in Ft (m)

1 Cable @ 3/4-in. dia. 100 (13.8) 40 (12.2) 2 Cables @ 3/4-in. dia. 200 (27.6) 40 (12.2) 3 Cables @ 3/4-in. dia. 338 (46.7) 40 (12.2) 4 Cables @ 3/4-in. dia. 418 (57.8) 40 (12.2) 1 Cable @ 1-in. dia. 150 (20.7) 40 (12.2) 2 Cables @ 1-in. dia. 340 (47.0) 40 (12.2) 3 Cables @ 1-in. dia. 506 (70.0) 40 (12.2) 4 Cables @ 1-in. dia. 706 (97.6) 40 (12.2)

6-2.11 Reinforced Concrete Knee Walls.

6-2.11.1 Description.

When a perimeter wall or fence line needs to also serve as a vehicle barrier, it must meet passive vehicle barrier standards. This can be achieved by using a reinforced concrete knee wall structure. A knee wall barrier is a wall resting on a footing. The entire footing and part of the wall are imbedded in the existing soil or in a crushed stone mix. Figures 6-28, 6-29 and 6-30 show representative cross sections of this type of barrier.

ASTM FOR FENCING 1

DOCUMENT NUMBER TITLE FENCE TYPE -

COMPONENT

*ASTM F2780

Standard Guide for Design and Construction of Expanded Metal Security Fences and Barriers

Expanded Metal/Design & Construction

*ASTM F2548

Standard Specification for Expanded Metal Fence Systems for Security Purposes

Expanded Metal/All

*ASTM F900

Standard Specification for Industrial and Commercial Steel Swing Gates

All/Gate

*ASTM F1184

Standard Specification for Industrial and Commercial Horizontal Slide Gates

All/Gate

*ASTM F2200

Standard Specification for Automated Vehicular Gate Construction

All/Gate

ASTM F537

Standard Specification for Design Fabrication, and Installation of Fences Constructed of Wood and Related Materials

Wood/All

*ASTM A1023/A1023M

Standard Specification for Stranded Carbon Steel Wire Ropes for General Purpose

All/Reinforcing

ASTM F1145

Standard Specification for Turnbuckles, Swaged, Welded, Forged

All/Reinforcing

NOTES:

1. This portion of the table, ASTM FOR FENCING, provides the ASTM Standard Specification/Standard Design and Construction specifications and requirements for the different fence systems indicated in this UFC. Not all are specifically referenced in this UFC. These specifications are provided for information and reference. Those specifically referenced in this UFC are indicated with an asterisk (*) and are in bold type.