A crash course on creating a vehicular perimeter security system

November 2007 Perimeter Security, Alarms & Intruder Detection

Keeping pedestrians safe, protecting structures from accidental or intentional automobile crashes, and force protection (keeping employees and visitors from harm) have always been a concern.

From pedestrian-filled farmers markets and universities to new and used car lots, a wide variety of agencies find peace of mind through the use of barriers, bollards, barricades and crash gates for vehicle-based physical access control at the perimeter.

Risk assessment starts with Physics 101

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. For example, a vehicle moving at 80 km/h has 25 times as much kinetic energy as it would at 16 km/h. Thus, an armoured car weighing 30 times as much as a Toyota Corolla and moving at 16 km/h would have less hitting power than the Toyota moving at 96 km/h!

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 66%, 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 common design deficiencies

As discussed above, linear thinking will not get you very far when planning a vehicular perimeter security system. Straight lines make for faster and easier approaches for vehicles, so it is 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, such as the Department of State (DOS) and military. Comprehensive reports of test results are issued and are available from the testing agency or manufacturer.

Today's barriers and bollards are capable of stopping and destroying a truck weighing up to 29 500 kg and travelling at 80 km/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 is 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.

One final area that should not be overlooked is aesthetics. With today's smart designs, it is no longer necessary to choose between form and function. You can have them both. Designers are creating secure environments with more compatible and aesthetically pleasing architectural elements.

If you visit the nation's Capitol today, for example, you will see landscaped islands at the north and south entrance drives which regulate vehicular access. If allowed to drive into the Capitol complex, you will cross over vehicle control barriers and bollards at the entrances. Indeed, all exits at the end of all drives are controlled with barriers, which pop from the ground when needed.

You will see similar barriers and bollards at refineries, distribution centres and headquarters offices of petrochemical and hydrocarbon companies, literally around the world.

Putting new vehicular threat tactics on the defensive

By their very nature, terrorist attacks are unpredictable and predicated on surprise. Staying one step ahead by identifying vulnerable areas, and securing them, is critical to staving off vehicular attacks.

That means being able to deploy security equipment in tough conditions, at a moment's notice. Fortunately, such equipment now exists in the form of portable, towable, temporary barriers. These barriers can be deployed quickly and effectively, even in places where it is impossible to excavate for a permanent foundation, such as the streets of Paris.

Terrorists typically do not go where they see barricades, so placing them wherever attacks can happen reduces security risks dramatically. Temporary barriers can protect facilities while permanent ones are being built, and they are even effective for the long-term where physical conditions preclude permanent solutions.

There are many types of available portable barriers and barricades:

Drop arm barrier: able to be deployed or relocated for full manual or automatic operation within two hours, these quick deployment barriers will stop and destroy a 6800 kg truck travelling at 48 km/h in less than 6 m. They secure an entrance roadway 2,4 to 7,3 m in width from vehicle attack. Hydraulic and manual versions are available.

Portable plate barricades: portable plate barricades 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 an 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 6800 kg vehicle moving at 48 km/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.

Permanent barriers and barricades

From parking lot security to stopping vehicles access at refineries, there are a variety of suitable barricades available. Solutions include high-security 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 7,3 m and up to 96 cm high. Lowered to allow passage of authorised 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 7,3 m.

Very high security, shallow foundation barriers are available for advanced counter-terrorism applications in sub-surface conditions that negate extensive excavations. This type of barricade was designed for the US Navy. Set in a foundation only 25 to 46 cm 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 3,2 to 7,3 m. 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.

Bollards are buff - and beautiful

When looking for a bollard solution, you choose the level of security you need. From protecting a headquarters to a warehouse or even a parked tanker, you can find a bollard system that will meet your needs.

Bollard systems operate individually or in groups up to 10 and are used for intermediate level security applications. Individual bollards are up to 33 cm in diameter, up to 89 cm high and are usually mounted on 1-1,5-m 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 4536 kg moving at 105 km per hour or a 9072 km vehicle moving at 74 km/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 aluminum 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.

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