The Access-Control Problem Traditional Systems Cannot See

A valid credential does not always mean a valid entry. Access control systems are very good at recording whether a card, code or QR scan was accepted — but they can’t tell you how many people actually walked through the door.

A valid credential is not the same as a verified entry

A card reader or mobile-credential system can log who requested entry, when, and whether access was granted. What it usually can’t answer is simpler and more important: how many people actually entered? Tailgating happens when an authorized person opens an entrance and a second person walks in without presenting their own credential — sometimes deliberately, often just because people hold doors for each other. From the access system’s point of view, nothing looks wrong: one valid credential, one logged event. What happened physically at the door can be very different.

Turning access logs into physical verification

Gatech’s tailgating detection layer adds another layer of verification on top of an existing access-control setup. Instead of looking only at access events, it also analyzes what actually happens at the entrance, then compares the two. If the access system recorded one authorized entry but the entrance shows two people passing through, that mismatch becomes something worth reviewing. The goal isn’t to replace the access-control system — it’s to surface information the access-control system can’t see on its own.

Why correlation matters more than raw detection

Simply detecting that multiple people are near a door creates a flood of irrelevant alerts, since busy entrances naturally have multiple people around them. What matters is whether the observed activity matches the permissions that were actually issued. By correlating entrance activity with access events, the system can tell the difference between two people entering on two valid scans, two people entering on one scan, someone entering with no matching access event at all, entry that follows a denied attempt, or a credential being used in a pattern that deserves a second look. The result is a system built around exceptions, not constant surveillance.

A review workflow, not an alarm flood

Not every unusual event is malicious, so the system is built around review rather than automatic judgment. A potential incident is presented with its event details and the relevant clip, so an authorized person can see exactly what happened, categorize it, and decide what to do — a far more practical workflow than manually comparing hours of footage against thousands of access records.

Working alongside what’s already there

None of this requires replacing existing access-control infrastructure or camera systems. The access-control system keeps managing credentials and permissions; existing cameras keep serving their normal security purpose. This layer sits between the two, making better use of information that already exists rather than rebuilding the security environment from scratch.