Perimeter security solutions: Knowing the key factors
Perimeter security is one of the most visible categories of security with bollards, sensors and barriers and one of the most effective at preventing direct attacks. It integrates a wide range of physical barriers and intrusion detectors, ensuring only authorized individuals have access to restricted areas. A look at perimeter products presents an overview of what solutions are available on the market and where they are used.
Designing a perimeter solution no longer means stringing barbed wire and erecting high fences. The perimeter solutions of today are more sophisticated, with sensors accurately detecting intruders, while ignoring false alarms from wind or small animals. Perimeter security is one of the most visible categories of security with bollards, sensors and barriers and one of the most effective at preventing direct attacks. It integrates a wide range of physical barriers and intrusion detectors, ensuring only authorized individuals have access to restricted areas. A look at perimeter products presents an overview of what solutions are available on the market and where they are used.
Effective Implementation
Evaluating possible threats and vulnerable areas is crucial for an effective perimeter solution. A perimeter security program typically contains up to four elements: detection, assessment, delay, and response, the intrusion detection system (IDS) provides the first element, detection, and often facilitates the assessment element. A perimeter intrusion sensor system is generally implemented as an input to a perimeter security management system. The IDS system generates an intrusion alarm signal, usually in the form of a zone alarm, indicating the relative location of an intrusion attempt. Most commonly, and especially in higher security applications, the intrusion sensor signal is used as a trigger to orient a CCTV camera on the zone of intrusion, and/or automatically switch the camera image to a monitor in the security control center. This facilitates the ability to assess both the validity of the signal as an actual intrusion attempt, and to determine the most appropriate response method.
Integrating the range of systems intrusion detection, video surveillance and often access controls part of the challenge perimeter vendors face today. The reason for all this hardware is to overcome the failings of security guards, who cannot be expected to keep an eye on all events in the perimeter of an area. With traditional methods, be they constant human surveillance (subject to human error, inattention and poor visibility constraints) or fence sensors of various kinds, the first two elements of Detect and Delay occur so late as to be squandered giving the intruder the advantage of surprise and time and once inside the perimeter, the intruder may not be adequately covered. Full control of the situation can only be attained by managing all four phases of perimeter defense. So a sensor is needed that sees well beyond the physical perimeter and that can track intruders within the perimeter fence as well.
Designing per location
Knowing the lay of the land plays an important role in deciding what functions are appropriate for different installations. Along with establishing the basic groundwork, understanding a location’s unique attributes helps deliver a targeted defense to effectively serve user needs. Adjusting the level of security for a factory and a nuclear silo makes an appropriate perimeter solution more useful than an overly sensitive or unresponsive one. If your environment is industrial or military, the fence line can be designed to create an imposing presence around your property conveying that you’re serious about site security and deterring attack. Sometimes a portable solution is preferred over a permanent one, such as for military bases and camps.
Some locations do not permit use of permanent barriers, such as when the sites are too shallow to dig barrier foundations, which make portable solutions preferable. The differentiating aspect of military bases is that they can move,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’s impossible to excavate for a permanent foundation.
Military users find portable perimeter systems secure yet flexible, this type of barrier provides a new element in force protection both , it’s especially relevant for threat conditions in the military, where there are a series of force protection issues. Having an increased level of security, when moving from locale to locale, is a big advantage.
Possible Threats
Identifying who would want to breach a location’s defenses helps define what sensors or barriers would be most appropriate for that location’s needs. A used car lot and a nuclear power plant would be broken into for different purposes, requiring different levels of protection.
To effectively detect walking, running or crawling human intruders, a short-range (30 meters or 100 feet) detection solution with wide-angle view is appropriate for monitoring gate areas. An increased range (107 meters to 183 meters or 350 feet to 600 feet) is better suited for complete perimeter protection. For sites facing higher security risks, such as a commercial or industrial site, a solution designed to prevent theft. This scenario has a higher threat level because assets are at stake,” he said. One would generally see a more experienced intruder with some degree of knowledge about detection technology. This individual would go to greater lengths to defeat the facility’s detection equipment, perhaps by attempting to crawl under the signal.
Preventing direct vehicular attacks
Less subtle attacks, such as deliberately crashing a vehicle into a barrier, become a serious consideration when designing perimeter solutions. Preventing vehicular crashes into protected areas makes up a key part of its evaluation process, 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.
As speed is needed for the most destructive impact, reducing it by placing barriers strategically is important. 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.
Integration Factor
Tying together video surveillance, intrusion sensors and barriers requires a high level of product knowledge and familiarity with specific locations. Some perimeter vendors specialize in one product sector, such as barricades. Others tackle all of a perimeter solution, from sensors to management software. Communications with the integration industry has illustrated that there is an increasing tendency to interlink the various elements of a security system intrusion alarm systems, CCTV systems, and access control, using network technology. More and more, security managers of major facilities want interconnections that can be managed and accessed via TCP/IP networks. Usually these are secure, ‘closed’ networks, but there is also substantial interest in open-access networks, of course with substantial firewall security to prevent access to the security system by unauthorized parties.
False alarms
While it may be useful to have sensitive alarms in high-security areas, added sensitivity also adds the possibility of false alarms. Eliminating false alarms, which cause frustration and lost time from patrolling, are a challenge. As false alarms also hurt the bottom line, perimeter vendors have taken steps to reduce them.
Crawling detection, needed to catch intruders, can also result in numerous false alarms. Zone length, along with ensuring overlapping areas, is a factor when assessing whether an alarm is a legitimate one. A video surveillance camera to visually verify if a disturbance is in fact a true threat is also important. When camera assessment is involved, maintaining zone length the head to head detection area at a maximum of 100 meters is optimal for clear visibility of the target. Increased sensitivity of a sensor requires more robust sensor signal processing in the sensor processing unit. The higher level of sensitivity of a fiber-optic sensor system mandates a high level of signal analysis to provide reliable detection of even stealthy intrusion attempts while eliminating alarms from non-threatening noise sources.
First, it conducts wind analysis. The most common source for nuisance alarms in fence-mounted cable-based intrusion sensor systems is wind, and (related) rain, instead of merely adjusting the sensitivity to suppress wind-induced signals, the APU (alarm processing unit) detects and recognizes cable disturbances that are the result of weather-induced motion and vibration. The sensor signal is then compensated so that these disturbances do not generate alarms. Second, event analysis compares sensor signals with defined parameters for each zone. “During system installation, each zone is ‘calibrated’ to match the response of the sensor to the physical performance of the fence or other barrier, variables like signal amplification, sensitivity, frequency response are adjusted according to the way the fence responds to intrusion attempts, as well as to non-threatening disturbances like wind. Last, alarm analysis determines how the system will respond to the signals.
Many things can cause a fence to react with a burst of noise, but an actual intrusion attempt will cause a series of disturbances within a given time frame, alarm processing sets the APU (alarm processing unit) to respond with an alarm output only when a series of disturbances meet the defined criteria, which again are adjusted to match the fence’s characteristics as well as the level of security required for a facility. If power stops or is deliberately cut, backup power systems keep the perimeter security systems running, designed into nearly every vendor’s solution. As power loss can trigger alarms, preventing interruption of power allows perimeter systems to operate effectively.
Arming Boundaries
As technology has improved, perimeter security has also grown to be more sophisticated. A secure location no longer needs to resemble a jail to provide adequate protection of people and assets within the boundaries. Even barriers can be discreet, yet effectively detect for intruders and eliminate nonevents in an outdoor situation, like wind or small animals. With the rise in integrated products, human operators can use one platform to monitor multiple systems, allowing for convenience and simplicity to detect threats. Outdoor perimeter security is a high-profile and crucial part of a complete security system, with integration developments worth watching.
