Does anyone else remember the good ol’ days when all you needed to secure your perimeter was to clear the land around your boundary and construct a palisade with some earthworks to fortify the line? Perhaps deploy a flock of guard geese and post some pilum-porting sentries, and you were set to stand off a horde? Of course, the notion of establishing a perimeter to protect interior spaces goes further back than the Romans, and perimeter protection principles, also known as the Five D’s, remain the same: Deter, Detect, Deny, Delay and Defend. A sixth D — Demarcation — while often not identified, is important to asserting spatial ownership as part of Crime Prevention Through Environmental Design’s territoriality concept.
The modern perimeter spans many forms, from high-security, access-restricted locations, such as military bases, to high-end luxury retail locations with significant foot traffic passing by the front door. Applying the Five D’s in any of these applications has the same principle of protecting interior assets, but with vastly different options, controls and permissive uses available. Importantly, effective psychological demarcation is an increasingly important characteristic of establishing a perimeter when standard techniques, such as fences, aren’t available.