Designing physical security for complex infrastructures

Flow-based Physical Security

“…[23]. According to Nunes-Vaz and Lord [2], "Security is concerned with the risks originating from the environment and potentially impacting the system, whereas safety deals with the risks arising from the system and potentially impacting the environment." In FM terminology, security is a machine with the function of handling security/safety concerns: malfunctions in different types of flows and triggering that result in malicious behavior or effects (see Figure 4).…”

“…To illustrate a type of security design based on FM, consider Nunes-Vaz and Lord"s [2] study case of a hypothetical facility required to reduce the risk associated with arrangement of threats to its physical security, visualized as a nested arrangement of zones. The required system is configured to prevent a hypothetical terrorist scenario involving a vehicle-based improvised explosive device, with the attacker also carrying firearms to coerce entry.…”

“…Figure 6 shows the initial unpopulated stage of the design. "The three function containers are initially unpopulated and the inevitable failure of the (unpopulated) detect function (shown by a dotted arrow below the detect container) leads to the least desirable output state of "inside without alarm"" [2]. In the next subsection, two cases of FM-based security are introduced.…”

“…A possible visualization of Nunes-Vaz and Lord"s [2] model is shown in Figure 8. Detection, Alarm, and Neutralization are types of spheres that can be described by their flows.…”

“…The increased complexity of physical infrastructures demands designing of effective physical security [2]. It has been found that a significant number of security incidents exploit some vulnerability of physical security [3].…”