1. Defense in Depth — Outside In
Physical security uses concentric layers — each one independent, each one harder to bypass than the last.
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Layer 1: Perimeter
Bollards · Barricades · Fencing · Razor wire
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Layer 2: Entry Control
Access control vestibule · Badge readers · Guards
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Layer 3: Surveillance
CCTV · Motion recognition · Object detection
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Layer 4: Personnel
Security guards · Two-person integrity · Access badges
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Layer 5: Environment
Lighting design · Sensor arrays
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Protected Asset
Servers · Data · People · Equipment
2. Vestibule Configurations
Three distinct configurations — different security levels for different environments.
| Configuration | Normal State | What Happens When Door Opens | Security Level | Use Case |
|---|---|---|---|---|
| All Doors Unlocked | All unlocked | Other doors automatically lock | Medium | Office buildings — free flow with anti-tailgating |
| All Doors Locked | All locked | Unlocking one prevents others from unlocking | High | Data centers, financial vaults — maximum control |
| One Open / One Locked | Both locked | When one is open, the other cannot unlock | High | Most common — balanced security and flow |
3. Sensor Type Comparison
Four sensor technologies, each with different operating principles and optimal use cases.
| Sensor Type | How It Works | Works in Dark? | Coverage Area | Best Use Case |
|---|---|---|---|---|
| Infrared | Detects heat (IR radiation) from warm bodies | ✅ Yes | Small to medium | Motion detectors, server rooms, stairwells |
| Pressure | Detects change in force/weight on a surface | ✅ Yes | Point / surface | Floor mats at entry points, window frames |
| Microwave | Emits microwave signals; detects movement in reflected signal | ✅ Yes | Large (100s–1000s m²) | Parking lots, warehouse floors, open perimeters |
| Ultrasonic | Emits sound waves; analyzes reflected echoes for motion | ✅ Yes | Medium enclosed | Server corridors, elevator lobbies, enclosed spaces |
4. Fencing Design Options
| Feature | Option A | Option B | Security Consideration |
|---|---|---|---|
| Visibility | Transparent (chain-link) | Opaque (solid panel) | Transparent = guards see outside; Opaque = conceals interior |
| Construction | Standard (easy to cut) | Robust (cut-resistant) | High-security requires cut-resistant materials |
| Height | Standard (1–1.5m) | High (2.4m+) | Higher = harder to climb without razor wire topper |
| Top Feature | None / barbed wire | Razor wire (concertina) | Razor wire is a strong climbing deterrent |
5. CCTV Feature Comparison
| Feature | What It Does | Security Benefit |
|---|---|---|
| Basic Recording | Continuously records video to storage | Post-incident forensics and evidence |
| Motion Recognition | Detects movement; triggers alerts/recording | Reduces need for continuous human monitoring; immediate alerting |
| Object Detection | Identifies license plates, faces, objects | Automated access control; flags unknown individuals |
| Networked Cameras | Multiple cameras linked to central recording server | Centralized management; overlapping coverage; no single point of failure |
6. Physical vs. Technical Security Controls — Integration Points
| Physical Control | Technical Integration | Shared Goal |
|---|---|---|
| Access Badge | RFID chip → badge reader → SIEM log entry | Identity verification + audit trail |
| CCTV + Object Detection | Camera feed → facial recognition software → alert system | Identity verification + intrusion detection |
| Vestibule Badge Reader | Badge swipe → access control server → door release signal | Access control enforcement |
| Two-Person Integrity | Two badge swipes required in same time window | Insider threat prevention |
| Sensor Array | Sensor trigger → alarm controller → guard notification | Intrusion detection + rapid response |