D3-Delay

by Robert Gruber, PSPMaster Halco Security Solutions Group

The third “D” of the 4 D's of perimeter security is “Delay.” So far, we have attempted to deter an intruder, and having failed to do that, we have detected him. We've established that there is an intruder who is making his way onto our property by attempting to breach our perimeter. So now, it is wise to delay that intruder, at least long enough to initiate and complete an appropriate response.

Delaying an intruder is easier said than done, as a determined trespasser will almost certainly breach the perimeter and the delay time that can be designed involves a matter of seconds rather than minutes or hours. Typically, we will design perimeter security in layers, just like interior protection is intentionally planned . The more secure the area has to be, the more layers of protection we will design and erect.

As an example, at a nuclear power plant, there are typically two (or more) fences. After breaching the first, the intruder will have to cross an area to approach the second fence, and then get through that one as well. The first fence may be regular chain link with sub-layers of protection in the form of barbed wire or razor tape on the inside of the boundary along with other mechanical detection devices.

Between the first and second boundary it’s important to build in additional deterrents via CPTED (Crime Prevention Through Environmental Design) and through the use of electromechanical devices. The second fence may be of a heavier gauge with increased layers of protection, such as razor mesh on both sides in several rolls. It’s sometimes useful, even essential, to design a third boundary (or more), depending upon the site and the vital assets within it. At this high security site, personnel who have already been on standby (24/7) would be sent out to deal with the intruder.

At a less secure facility, there may be only one fence with an offset and a few strands of barbed wire. The response may only take the form of turning on a camera, turning on a video recorder, and alerting a security guard. Responses can take many forms: lights can be turned on, sirens sounded, and / or personnel dispatched to the intrusion location. The main concern with "delay" is that you design it to be long enough to fulfill the response time. The response, of course, is designed to "DENY" access to an intruder. We’ll cover that step next time.