What is a common design feature in effective physical protection plans?

A series of barriers is a fundamental design feature in effective physical protection plans because it creates multiple layers of security that enhance the overall defense strategy. By employing a series of barriers, an organization can deter unauthorized access more effectively, as each layer requires time and effort to breach. This can significantly slow down potential intruders, allowing security personnel more time to respond to incidents.

Incorporating multiple barriers also allows for a strategic approach where different types of barriers can be employed according to the specific risks associated with different areas of a facility. For example, while certain high-security areas might utilize reinforced fences or walls, more accessible areas may employ gates or access control points. This layered approach minimizes vulnerabilities and enhances the overall protective environment.

Other options, while they may contribute to security in specific contexts, do not provide the same comprehensive approach as a series of barriers. Single barricades may not effectively contain threats on their own, and while reinforced structures and closed circuit systems are important, they typically serve as part of a broader coordinated effort rather than a standalone feature central to a physical protection plan. Thus, the use of multiple barriers stands out as a key element in creating a resilient physical defense.