|
STOPPED IN THEIR TRACKS
Car bombs are one of the most popular deployments in the terrorist’s arsenal. David Dickinson looks at how new developments in perimeter security can help reduce the risk of a car bomb attempt being successful
 A vehicle moving towards a barricade has a certain kinetic energy, which is the major measure
of how much ‘hitting power’ it possesses
It’s self-evident that the world of physical security has changed in response to the pervasive threat of terrorism around the globe. Where many facility managers were once criticised for taking extreme and expensive perimeter security measures, the question today is not whether to implement them, but simply how best to do it.
Whether a refinery, distribution centre or corporate headquarters, finding the right perimeter security solution is essential to protecting both lives and property.
Risk assessment
When evaluating the security risk for a given facility, particular attention must be focused on the weights and velocities of vehicles that would be used to attempt penetration into sensitive areas.
A vehicle moving towards a barricade has a certain kinetic energy, which is the major measure of how much ‘hitting power’ it possesses. Mathematically, kinetic energy is derived from the vehicle velocity and its weight (mass). On impact, some of this energy is converted to heat, sound and permanent deformation of the vehicle. The barricade must absorb the remainder of this energy if the vehicle is to be stopped.
The amount of remaining energy varies depending on many factors, primarily the velocity of the vehicle at the moment of impact. The amount of kinetic energy posed by a vehicle changes as the square of its velocity.
Because of the relationship of velocity to the total kinetic energy possessed by the vehicle, every effort must be made by the security engineer to force a vehicle to slow down before it reaches the barricade. The most frequently used technique is to require a sharp turn immediately in front of the barrier. When vehicle speed is reduced by 50% the ‘hitting power’ is reduced by four times. If the speed is reduced by two thirds the force of impact will be reduced by nine times.
Upon designing a way to slow down vehicle approach, precautions should also be taken that the attacking car cannot make a ‘corner cutting shot’ at a barricade. Often, only a light post defines a turning point and a speeding car can take it out and not even hesitate. Knolls and other impediments should be considered.
Failing to understand this and not using the proper equipment to counter the threat may lead to a false sense of security.
Overcoming design deficiencies
Linear thinking won’t get you very far when planning a vehicular perimeter security system. Straight lines make for faster and easier approaches for vehicles, so it’s best to create curves on the access roads to your facility as a natural impediment to speeding cars or trucks.
Another common planning deficiency occurs when designers choose non-certified barriers or barricades. Certified equipment has been tested and proven to work under extreme conditions – giving planners the confidence they rely on.
No area is more critical to the vehicle barrier selection process than testing. Without adequate testing, there is no assurance that the barrier will resist the threat. Testing is normally by an independent testing company or government agency.
Today’s barriers and bollards are capable of stopping and destroying a truck weighing up to 29,000+ kg and travelling at 80km/h. Such barricades can be raised or lowered at will to stop traffic or let it through. In an emergency, the thick steel plates or bollards pop out of the ground within 1.5 seconds.
When integrated properly into a total system, including fences, lights, alarms, gates and other security components, vehicle barriers are a key measure in preventing threats to sensitive resources. It’s important to consider supplemental gate and fencing reinforcements that may also be needed to optimise vehicle barrier effectiveness.
In designing a barrier system, you must also consider whether to use a passive or active system. Normally, an active system keeps the barrier in the active or up position. It must be deactivated to permit access. Active systems are preferable to ones that must be activated to prevent access because they are more secure.
Temporary barriers
By their very nature, terrorist attacks are unpredictable and predicated on surprise. That means being able to deploy security equipment in tough conditions, at a moment’s notice. Portable, towable, temporary barriers can be deployed quickly and effectively, even in places where it’s impossible to excavate for a permanent foundation, such as the streets of Paris.
First used successfully to protect NATO troops in Kosovo and elsewhere, these modular, portable solutions can be rapidly set up on existing concrete or asphalt roads, level compacted soils and other hard surfaces. No excavation or sub-surface preparation is required. With portable barriers and barricades, you can begin installation in the morning and have protection by lunch.
Terrorists typically don’t go where they see barricades, so placing them wherever possible attacks can happen reduces security risks dramatically. Temporary barriers can protect facilities while permanent ones are being built, and they’re even effective for the long-term where physical conditions preclude permanent solutions.
There are many types of available portable barriers and barricades:
■ Drop arm barriers: These are able to be deployed or relocated for full manual or automatic operation within two hours and will stop and destroy a 6,800 kg truck travelling at 48km/h in less than 20 feet 6m. They secure an entrance roadway three to eight metres in width from vehicle attack. Hydraulic and manual versions are available.
■ Portable plate barricades: These provide security against vehicle based terrorism or thefts for high-cycle locations such as the entrances to large office facilities, government agencies and military bases. Able to be deployed in high traffic locations for full manual or automatic operation within two hours, the quick deployment modular barricades feature a phalanx-type rising plate barrier mounted within multiple inertial pods. The plate barrier lies level to the ground to allow vehicles to pass and is raised or lowered into position utilising a hydraulic cylinder driven by a hydraulic power unit. The hydraulic pumping unit can be sized to provide pass-through rates suitable for most inspection and identification station requirements.
■ Towed portable crash barriers: Able to be deployed in 15 minutes, the newest portable high security vehicle crash barriers can quickly protect facilities and people from vehicle attacks and accidents. These mobile crash barriers can be towed into position by a medium-sized pick-up truck or equivalent. The mobile barrier deploys in 15 minutes and operates locally or remotely for guard protection. Deployment, retrieval and operation are all hydraulic. The barriers stop and disable a 66.7kN vehicle moving at 30mp/h/48km/h. These portable crash barriers were built for US federal government security specialists wanting a system that could be rapidly deployed and then operated as a regular security gate or barrier system. They would be just at home protecting a farmer’s market. Once positioned, the mobile barricade is separated from its transporter and lowered into position by means of a battery-operated hydraulic power system, which is then used to raise or lower the barrier for normal or emergency tasks.
The controls to run the barrier can be located on the barrier, at a fixed secure post, or from a hand-held push button controller. The guard need not go to the barrier to raise or lower it from its guard position. Within 15 minutes of being sited, the mobile crash barrier lowers itself into position with built-in hydraulic jacks. There is no hand
cranking. Wheels are stored at the sides and then the vehicle ramps are folded out, completing the deployment.
Permanent barriers and barricades
From parking lot security to stopping vehicle access at refineries, there are a variety of suitable barricades available. Solutions include highsecurity surface mounted barricades, cable beam barricades, high security barriers and very high security, shallow foundation barriers.
High security barriers are all crash rated in widths up to 7315mm in width and up to 965mm high. Lowered to allow passage of authorized vehicles, these barriers are the first line of defence at critical facilities. High-security surface mounted barricades allow quick installation into difficult locations such as parking structure ramps or areas with sub-surface drainage problems. These crash-rated barricades are lowered to allow passage of authorised vehicles and are available in widths up to 7315mm.
Very high security, shallow foundation barriers are available for advanced counter-terrorism applications in sub-surface conditions that negate extensive excavations. Set in a foundation only 25cm to 45cm deep, these shallow foundation barriers are able to survive and operate after a 1.2 million foot pound impact. With its shallow foundation and aesthetic design, they are major breakthroughs in high duty, anti-terrorist barricades.
The shallow foundation barriers eliminate concerns about interference with buried pipes, power lines and fibre-optic communication lines. The shallow foundation also reduces installation complexity, time, materials and corresponding costs. These types of barriers are suitable for high water table locations and areas with corrosive soils.
Cable beam barricades are available in hydraulic and manually operated models. All are crash rated with one version enhanced for higher security applications. The clear openings range from 3200mm to 7315mm. One model is configured as a swing gate for use where vertical lift is impractical. All other models are raised to allow passage of authorised vehicles.
Bollard solutions
When looking for a bollard solution, you choose the level of security you need. Bollard systems operate individually or in groups up to ten and are used for intermediate level security applications. Individual bollards are up to 323mm in diameter, up to 889mm and are usually mounted on 1-1.6m centres. Hydraulic versions can be operated by a variety of control systems. Manual versions are counter balanced and lock in the up or down position. All models are crash rated and lower to allow passage of authorised vehicles.
They are tested to stop and destroy an attacking vehicle weighing 44.4Kn moving at 104km/h or an 88.9Kn vehicle moving at 74km/h. With bollards you can create the look you want. Ranging from faceted, fluted, tapered, rings and ripples, colours, pillars, to shields, emblems and logos, bollards are aesthetically pleasing and versatile. You can specify ornamental steel trim attached directly to the bollard, or select cast aluminium sleeves, which slip right over the crash tube. Bollards can be galvanised for corrosion resistance, fitted with an internal warning light for increased visibility and engineered to suit high traffic volume. If damaged, simply slip off the old and slip on the new.
Other considerations
Hydraulic power system features: the hydraulic power and control system should have a wide range of security features built into its logic circuits, including power off operation, dual speed operation for emergency mode actuation, instant reverse, multi- barricade operation (either tandem or parallel), and operation by radio, card reader, remote control panel, key-switch or combinations thereof.
Barricade Control: The barricade control circuit should accept a wide range of control signals. Radio, card readers, key switches, remote control push button stations or other security systems can be readily interfaced.
Vehicle detector systems: To alert the guards of an approaching high speed vehicle, be sure that you incorporate a velocity sensor utilising digital inductive loop technology. Wire loops are embedded in the roadway at a location distant from the guard booth or facility entrance. The system can be set to trigger an early warning alarm or actuate the barricades when a vehicle approaches at a velocity above the user-defined set point.
Safety Loops: In high traffic cycle operations, guards can make errors by pushing controls at the wrong time, lifting authorized vehicles. If vehicle-sensing loops are placed in the roadway directly in front and behind the barricade, the coupled loop detector suppresses accidental operation. The guards still have complete control using the emergency mode, which overrides the safety loop.
Drainage-surface and sub-surface water: In many site locations, the barricade is protected from rain or surface run off so special provisions are not necessary. As the amount of water entering the barricade foundation, whether from sub surface water or surface water increases, it is necessary to make provision for its disposal. By far the best technique is to include a gravity drain. Where the amount of water is negligible, the sub-surface soil is often porous enough to accept any run off or seepage. You may also want to install a small capacity, self-priming pump.
Protection from corrosion: Ask for a coal tar epoxy undercoat for all below grade structural members and corrosion resistant white gloss enamel for the top surfaces. Road plates should be texture treated for a non-skid surface. Yellow/black highway safety striping can alert drivers to the barricade when raised. Galvanising and/or sacrificial anodes should be considered when soil conditions are especially harsh.
Temperature environment: Most barricades can be operated from - 28°C to 63°C. However, it may be necessary at the lower temperatures to protect against incidental water and slush being carried into the barricade and forming a solid ice mass. The hydraulic power system should be in a protected space in extremes of temperature. It is recommended that the ambient temperature be maintained above freezing or that a reservoir tank heater be added to the power system.
Power Off Operation: An optional feature available with some series of barricades is the ability to operate the barricade even with a power interruption. In this option, hydraulic fluid is stored under pressure and is available for operating the barricades at anytime.
A manual hand pump should also be furnished as standard equipment in event of a prolonged power blackout or motor/pump failure. Lastly, barricades will usually lower themselves by gravity without the aid of the pump when the down command is given.
 David Dickinson is senior vice president of Delta Scientific. For more information visit: www.deltascientific.com
|