Author: Osiris

Tailgating, sometimes called piggybacking, happens when an unauthorized person follows an authorized person through a secured door before it closes and locks, quietly defeating an access control system without ever presenting a credential. It remains one of the most common real-world ways access control gets bypassed, largely because it exploits ordinary politeness rather than a technical flaw.

Detection Versus Prevention

Anti-tailgating technology falls into two broad categories: detection systems that sense a violation and alert security staff after the fact, and prevention systems that physically stop the second person from entering at all. Detection approaches include infrared or thermal sensors mounted above a doorway that count how many people pass through per credential swipe, and video analytics that visually track individuals entering a controlled space. These systems are lower cost and easier to retrofit into existing doorways, but they rely on a human response to an alarm rather than stopping the intrusion outright.

How Mantraps Physically Prevent Piggybacking

A mantrap, also called an interlocking vestibule, is a small enclosed space with two doors that are never both unlocked at the same time: a person must pass through the first door, have it lock behind them, and only then can the second door open, typically after a sensor confirms only one person is present in the vestibule. This makes it physically impossible for a second, uncredentialed person to slip through alongside an authorized individual, which is why mantraps are standard in the highest-security environments, including data centers, pharmaceutical facilities, and secure government spaces.

Sensor Technology Inside the Vestibule

Modern mantraps typically use overhead infrared beams, weight-sensing floor plates, or 3D depth sensors to verify occupancy before releasing the second door, since simple beam sensors alone can sometimes be fooled by unusual body positions or objects carried through the space. Some higher-security installations also require a second credential check or biometric verification at the interior door, adding an additional layer beyond simple occupancy counting.

FAQ

What is the difference between a mantrap and an airlock-style vestibule? The terms are often used interchangeably in security contexts; both describe a two-door interlocking space where only one door can be open or unlocked at a time.

Can mantraps handle wheelchairs or large deliveries? Many facilities install a separate, staff-monitored accessible or delivery entrance alongside a mantrap, since the enclosed vestibule space can be too small for wheelchairs, carts or bulky equipment.

Are camera-based tailgating detection systems as effective as mantraps? Detection-based systems are useful for lower-risk areas and can flag violations for review, but they do not physically prevent an intrusion the way a mantrap does, which is why the highest-security spaces typically use mantraps rather than detection alone.

Turnstiles are one of the oldest access control technologies still in widespread use, and for good reason: paired with a card reader or biometric scanner, a turnstile physically enforces that only one person passes per valid credential, something a door alone cannot guarantee. Choosing the right type is a balance between throughput, security level and how a site wants to present itself to visitors.

Waist-Height Turnstiles for High Throughput

Waist-height turnstiles, the tripod or drop-arm style common in stadiums, transit stations and office lobbies, prioritize speed, letting large numbers of people pass quickly while still enforcing single-person entry per credential. Their tradeoff is security level: a determined person can climb or vault over a waist-height barrier, which is why they are typically paired with a security guard or camera coverage rather than deployed as a standalone security measure in high-risk environments.

Full-Height Turnstiles for Higher Security

Full-height turnstiles, which resemble a rotating cage extending from floor to ceiling, physically prevent climbing over or crawling under, making them the standard choice for unstaffed perimeter entrances at data centers, utilities and other facilities where an unauthorized entry cannot rely on a guard noticing in time. The tradeoff is throughput and cost: full-height units process people more slowly and take up significantly more space and budget than waist-height alternatives.

Optical and Sensor-Based Lanes

A newer category, optical turnstiles or speed lanes, uses infrared sensors rather than physical arms to detect unauthorized passage, sounding an alarm or triggering a barrier only when someone attempts to pass without a valid credential or follows too closely behind an authorized person. These systems offer a more open, modern appearance favored in corporate lobbies, but they generally rely on integration with video analytics or a staffed reception desk to respond to detected violations rather than physically stopping them outright.

Matching the Barrier to the Risk

Security consultants typically select turnstile type based on the consequence of an unauthorized entry, the expected volume of legitimate traffic, and whether the location has staff present to respond to an alarm. A single site often uses different turnstile types at different entrances, for example optical lanes at a staffed main lobby and full-height turnstiles at an unstaffed rear or loading-area entrance.

FAQ

Can turnstiles alone stop tailgating? Waist-height and optical turnstiles reduce tailgating but do not fully prevent a determined person from following closely behind an authorized individual; full-height turnstiles and mantrap-style systems provide stronger physical prevention.

Are full-height turnstiles required for data centers? Not universally required by code, but they are a common industry best practice for unstaffed high-security entrances where climbing over a barrier must be physically prevented rather than just detected.

Do optical turnstiles work with mobile credentials? Yes, most modern optical turnstile systems integrate with the same card, mobile or biometric credential readers used elsewhere in a facility’s access control system.