Assessing risks from vehicular crashes is part of designing an outdoor perimeter solution. In this article, David Dickinson, Senior Vice President of Delta Scientific, discusses some of the issues that need to be taken into consideration for a secure yet aesthetic perimeter.
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 50 mph (80 kph) has 25 times as much kinetic energy as it would at 10 mph (16 kph). Thus, an armored car weighing 30 times as much as a Toyota Corolla and moving at 10 mph (16 kph) would have less hitting power than the Toyota moving at 60 mph (96 kph)!
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 percent, 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.
Where turns cannot be created, many are turning to an Early Warning System. This system is best applied at locations where there is a long and relatively straight run into the facility that would allow a large vehicle to build up its speed. A vehicle traveling at 60 mph (96 kph) can cover 88 feet per second (2.68 m/sec) so it is imperative that the guards be alerted immediately.
Continuous Doppler radar picks up instantaneous changes in velocity and addresses the threat scenario in which an inbound vehicle approaches at normal speeds and then accelerates to commence the attack. It will also send a warning if a hidden vehicle suddenly passes a larger vehicle and attempts an attack. Once alerted, the guards can take action, including raising the barrier systems.
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 noncertified 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 U.S. 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 65,000 pounds (29,454 kg) and traveling at 50 mph (80 kph). 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 might be needed to optimize 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 U.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 centers 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 and 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 possible 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 15,000 pound (6,800 kg) truck traveling at 30 mph (48 kph) in less than 20 feet (5.5 m). They secure an entrance roadway eight to 24 feet (3.2 9.6 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 utilizing 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 10 to 15 minutes, the newest portable high security vehicle crash barriers can quickly protect facilities and people from vehicle attacks and accidents. Some mobile crash barriers can be towed into position by a golf cart. The mobile barriers operate locally or remotely for guard protection.
Deployment, retrieval and operation are all hydraulic. The barriers stop and disable a 15,000-pound (6,818 kg) vehicle moving at 30 mph (48 kph). These portable crash barriers were built for U.S. federal government security specialists wanting a system that could be rapidly deployed and then operated as a regular security gate or barrier system. Once positioned, the mobile barricade is separated from its transporter and lowered into position by means of a batteryoperated hydraulic power system, which is then used to raise or lower the barrier for normal or emergency tasks. Commercial versions are just as well-suited for protecting a farmer's market and other business events from errant drivers. Light enough to be towed by a golf cart and set up in only 10 minutes, the DSC 1000 portable barrier passed an ASTM crash test, stopping a 5,000-pound (2,300 kg) vehicle going 40 mph (64 kph), providing it with an ASTM rating of P40.
Contrary to the "hard stop" wanted with antiterrorist crash-tested barricades, testing of the new DSC 1000 demonstrated that the collision did not distort the passenger compartment of the vehicle. Instead, Soft Stop technology decelerates and stops the vehicle over a short distance, referred to as "occupant ride down acceleration." This protects the errant driver as well as pedestrians.
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 288 inches (732 cm) and up to 38 inches (96.5 cm) high. Lowered to allow passage of authorized vehicles, these barriers are the first line of defense at critical facilities.
High-security surface mounted barricades allow quick installation into difficult locations such as parking structure ramps or areas with subsurface drainage problems. These crash-rated barricades are lowered to allow passage of authorized vehicles and are available in widths up to 288 inches (732 cm).
Very high security, shallow foundation barriers are available for advanced counter-terrorism applications in subsurface conditions that negate extensive excavations. This type of barricade was designed for the U.S. Navy. Set in a foundation only ten to 18 inches (25.4 45.7 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, antiterrorist barricades.
The shallow foundation barriers eliminate concerns about interference with buried pipes, power lines and fiber 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 10.5 to 24 feet (4.2 9.6 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 authorized vehicles.
Bollards Are BuffAnd 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.
With a foundation only 14 inches (35.5 cm) deep versus the four feet (1.2 m) typically required, the new DSC 600 Fixed Shallow Foundation Bollards can be installed within sidewalks, on top of concrete deck truss bridges or in planters as well as conform to the inclines and turns of a locale. The new two-bollard modules, which can be arrayed in whatever length is required, will stop and destroy a 15,000-pound (66.7 kN) truck traveling 50 miles per hour (80 kph).
They have already successfully passed a K12 rating crash test, providing proof of their ability to provide high-energy stops. It is the first Shallow Foundation Bollard to meet the U.S. Department of State Specification, Revision A, that requires the bed of the attacking truck to go less than 39 inches (1 m) beyond the point of impact.
Bollard systems that raise or lower can operate individually or in groups up to 10 and are used for intermediate level security applications. Individual bollards are up to 12.75 inches (32.39 cm) in diameter, up to 35 inches (88.9 cm) high and are usually mounted on 3 to 5 foot (1.2 2 m) centers. 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 authorized vehicles.
They are tested to stop and destroy an attacking vehicle weighing 10,000 pounds (4,545.5 kg) moving at 65 miles per hour (104 kph) or a 20,000-pound (9,091 kg) vehicle moving at 46 miles per hour (73.6 kph).
With bollards, you can create the look you want. Ranging from faceted, fluted, tapered, rings and ripples, colors, 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 over the crash tube. Bollards can be galvanized for corrosion resistance, fitted with an internal warning light for increased visibility and engineered to suit high traffic volume. If the bollards are damaged, simply slip off the old and slip on the new.
No Application Too Large or Small
Protecting perimeters of facilities is no small responsibility. Knowing you have got the right equipment in place to secure a facility and to prevent human tragedy brings a peace of mind that no amount of money can buy. Carefully researching available options and consulting with experts will ultimately lead to the right solution.