What Is an Access Control Mantrap (Airlock)? Applications in Banks, Data Centres & Secure Facilities

An access control system at a bank IT room can verify that an authorised employee's card and fingerprint are presented. It cannot stop that employee from holding the door open as they enter, allowing an unauthorised colleague to slip through behind them — a practice so common in corporate environments that security professionals have a name for it: piggybacking.

The mantrap eliminates piggybacking by physical design. It is the only access control mechanism that can definitively enforce single-person-per-authentication entry — regardless of human cooperation or negligence. For the most security-critical access points in Bangladesh's banks, data centres, and secure facilities, a mantrap is not an optional enhancement. It is the architectural component that makes multi-factor authentication meaningful.

What Is a Mantrap?

A mantrap (also called an airlock, security vestibule, or man-trap) is a two-door access control system where the second door cannot open until the first door has fully closed and locked. This sequential two-door configuration creates a sealed intermediate chamber — the mantrap chamber — that a person must pass through to complete entry.

The Core Security Principle

The security guarantee of a mantrap rests on one rule: at no time can both doors be open simultaneously. The interlocking mechanism ensures:

• Door 1 opens: After valid credential presentation, person enters the chamber. Door 1 closes and locks behind them.
• Authentication in chamber: The person provides additional authentication factor(s) inside the chamber. Only now does Door 2 open.
• Door 2 opens: Person exits into the secured zone. Door 2 closes and locks.

At every moment, at least one door is locked. It is physically impossible to tailgate through a correctly designed mantrap — when the outer door opens, the inner door is locked, and when the inner door opens, the outer door is already locked.

Anti-Tailgating and Anti-Piggybacking Mechanisms

Occupancy Sensing: One Person Only

The most critical security feature of a high-security mantrap is occupancy verification — confirming that only one person is in the chamber at a time.

Weight sensor platform: A load cell under the floor of the mantrap chamber measures the weight of the occupant(s). If the measured weight exceeds the configured single-person range (typically 40–120 kg, adjusted for the specific population), the inner door will not open and an alarm is triggered. Two people entering the chamber together will exceed the single-person weight range.

Infrared beam array: Multiple horizontal IR beam pairs scan the chamber vertically. A single person standing in the chamber creates one body profile. Two people side by side or one behind the other create different beam interruption patterns that the system classifies as multiple-person occupancy.

AI camera-based occupancy detection: An overhead camera in the ceiling of the chamber uses person detection AI to count heads and body outlines. This is the most accurate method, handling edge cases (e.g., a very large person whose weight might equal two small people) that weight sensors alone cannot resolve.

Enterprise mantrap systems (Gunnebo, Boon Edam): Use combined weight sensors + IR array + camera for multi-factor occupancy verification.

Anti-Passback Integration

The mantrap integrates with anti-passback rules in the access control system. An authenticated credential cannot be used to enter again without a corresponding exit event. This prevents:

• A person entering the mantrap with a stolen card and then using the same card to enter the secured zone again
• A person exiting the mantrap passing their card back through a gap for another person

Interlocking Door Logic

The interlocking mechanism — the core of mantrap security — can be implemented in two ways:

Mechanical Interlocking

A direct mechanical linkage between the two door locks prevents both from unlocking simultaneously. No power or control system is required for the interlock — it operates on physics. The mechanical interlock remains active even during power failure (combined with fail-secure locks on both doors).

Advantage: Cannot be defeated by software or control system failure. The physical mechanism is the ultimate guarantee.

Limitation: Cannot be overridden in software for emergency conditions — requires physical intervention.

Electronic Interlocking (Software Logic)

The access control controller implements interlocking in software: it reads door status sensors (open/closed) and controls door strikes/maglocks accordingly. The controller does not allow the second door to unlock until the first door's closed sensor confirms the door is shut.

Advantage: Configurable, supports emergency overrides, integrates with fire alarm systems for evacuation mode.

Limitation: Software bugs or hardware failures in the controller could potentially allow both doors to open simultaneously — mitigated by hardware interlocking override contacts.

Best practice: Implement electronic interlocking as the primary logic with a hardware interlocking circuit as a backup, particularly for bank vault and data centre Tier III/IV applications.

Mantrap Dimensions

Mantrap dimensions are governed by the number of persons it must accommodate and wheelchair accessibility requirements:

For Bangladesh Bank IT rooms where Bangladesh Bank compliance audits evaluate the access control installation, a 1.2m × 1.2m internal mantrap with biometric authentication is the recommended standard specification.

Authentication in the Mantrap Chamber

The mantrap creates a controlled space where authentication can be conducted without the pressure of an open corridor. Authentication in the chamber is typically more rigorous than outer-door authentication:

Standard Bank IT Room Configuration (Bangladesh Bank Compliance)

Outer door: MIFARE DESFire card presentation Outer door opens, person enters chamber, outer door closes.

Inner door: Fingerprint biometric or facial recognition Inner door opens only after successful biometric match of the person currently in the chamber.

Anti-passback: The credential cannot be used again without corresponding exit event.

CCTV camera in chamber: Mandatory for Bangladesh Bank compliance — records who enters and exits the IT room mantrap.

This configuration satisfies Bangladesh Bank ICT Security Guideline's biometric mandate for IT rooms while adding the anti-tailgating guarantee of the mantrap architecture.

Data Centre Tier III/IV Configuration

Outer door: MIFARE DESFire card + facial recognition (2FA) Occupancy verification: Weight sensor + IR beam confirms single occupancy Inner door: PIN entry (3FA) OR second biometric (second finger, iris) CCTV: Camera records mantrap occupant from overhead Anti-passback: Enforced at both inner and outer doors

This 3FA configuration within a mantrap with occupancy verification is the highest available security level for physical access control in commercial applications.

Emergency Override

Every mantrap must have an emergency override mechanism:

• Fire alarm integration: When a fire alarm activates, all mantrap doors release to allow free evacuation
• Manual override: A key-controlled override allows security personnel to open both doors for emergency access
• Duress mode: Some systems support a hidden "duress code" that opens the door while simultaneously alerting security (used when someone is forced at gunpoint to authenticate)

Bangladesh Bank IT Room Compliance

Data Centre Applications

Commercial data centres in Bangladesh (including Banglalink DC, Reve Systems, BDCCL, and others) follow international Tier III and Tier IV standards that require mantrap access control at zone boundaries:

Data centre zone hierarchy:

• Outer perimeter: Building entrance mantrap (card access)
• Data hall entry: Main data hall mantrap (card + biometric, single occupancy enforced)
• Cage / suite entry: Individual tenant cage mantrap (card + PIN, tenant-controlled)
• Hot aisle containment: Some Tier IV designs include mantrap access to contained aisles

The mantrap ensures that no one can enter a higher-security zone by tailgating an authorised person — critical in multi-tenant environments where one tenant's employees should never have access to another tenant's equipment.

Product Recommendations

Gunnebo (Sweden) — Premium Mantrap Systems

Gunnebo is the global market leader in security portals and mantrap systems. Their STL series (single door security portal) and double-door mantrap configurations are specified for the highest-security banks, central banks, data centres, and government facilities globally.

Gunnebo Evolum Security Airlock: Double-door mantrap with mechanical interlocking, weight sensor occupancy verification, and integration with any major access control platform. Custom dimensions available. Premium build quality with stainless steel and glass construction. Suitable for Bangladesh central bank, commercial bank headquarters, and Tier III/IV data centres.

Boon Edam (Netherlands) — Security Revolving Doors and Portals

Boon Edam's Tourlock security revolving door series provides mantrap-equivalent security in a revolving door format — more space-efficient than a traditional two-door configuration and capable of higher throughput for facilities needing both security and efficient access.

Bosch (Germany) — Integrated Security Portals

Bosch's access control ecosystem includes security portal integration through the Bosch ACS-4 platform. Bosch specifies their mantrap solutions with OSDP v2 encrypted communication on all readers, deep integration with BVMS for camera synchronisation, and enterprise-grade reliability.

Local Bangladesh Fabrication

For lower-budget applications, locally fabricated mantraps with imported interlocking hardware (Abloy, ASSA ABLOY locks, Gunnebo interlock mechanisms) are available through specialist security contractors. These are suitable for IT rooms at smaller bank branches but are not recommended for vault-level or data centre security where precision engineering and fail-safe guarantees are required.

Applications Summary

Key Takeaways

• A mantrap eliminates tailgating and piggybacking by physical architecture — it is the only mechanism that definitively enforces single-person-per-authentication entry
• The core mechanism: outer door must fully close before inner door can open — one door is always locked
• Occupancy verification (weight sensor + IR + camera) confirms single occupancy in the chamber before the inner door opens
• Bangladesh Bank's ICT Security Guideline biometric requirement for IT rooms is most effectively satisfied by a mantrap with biometric inner-door authentication
• Data centre Tier III/IV standards require mantrap access at zone boundaries — essential for multi-tenant data centres in Bangladesh
• Gunnebo and Boon Edam are the global premium mantrap manufacturers; Bosch integrates mantrap hardware with enterprise access control platforms

Ready to Install a Mantrap at Your High-Security Access Points?

SSAL designs and installs mantrap access control systems for Bangladesh banks, data centres, pharmaceutical facilities, and government secure areas. Our team specifies the appropriate mantrap configuration, authentication level, and occupancy verification technology for each application — and integrates the system with your existing access control and CCTV infrastructure.

Contact SSAL for a free mantrap consultation:

• Phone: +880 1799-986890
• Email: info@smartsafety.com.bd
• Web: www.smartsafety.com.bd
• Office: Youth Tower Level 2, 822/2 Rokeya Sarani, Dhaka-1216

Preparing for a Bangladesh Bank IT room compliance inspection? Request a free IT room access control compliance assessment — our team reviews your current setup against Bangladesh Bank ICT Security Guideline requirements and recommends the most cost-effective path to full compliance, including whether a mantrap is required for your specific installation.