Understanding tailgating and access security in high-security environments

Maintaining secure access to sensitive areas is fundamental to safeguarding people, property and information. Yet even in highly controlled environments, some of the most serious breaches occur not through complex cyberattacks, but through something far simpler: tailgating. Whether intentional or not, tailgating remains one of the least visible yet most damaging vulnerabilities in physical security. For organisations operating high-security sites such as datacentres, laboratories or restricted operational zones, understanding and addressing this risk is essential.

What is tailgating?

Tailgating, sometimes called piggybacking, happens when an unauthorised person slips into a restricted area by closely following someone who is permitted to enter. It often begins with something as ordinary as a door being held open out of courtesy, or an employee being momentarily distracted as they badge in. In other situations, it is more calculated. Someone may deliberately take advantage of the trust, politeness or busy environment of a workplace to move through an access point unnoticed. Access control systems are designed to verify credentials, but they cannot always determine how many people walk through once the door is released.

Although tailgating may appear harmless at first glance, it can set the stage for far more serious breaches. Gaining a foothold inside a secure zone gives an intruder the opportunity to reach equipment that stores sensitive information, access devices connected to a corporate network or gather documents they would not otherwise see. What begins as a physical intrusion can quickly blur into a genuine threat. For organisations that rely on the confidentiality and integrity of their data, these scenarios carry clear operational and financial risks.

Tailgating tactics vary, but many rely on social cues. A common approach is for an intruder to present themselves as a colleague who has misplaced their card. They appear friendly, hurried or familiar enough to avoid suspicion. Others dress as delivery drivers or contractors. They use packages or equipment to create the impression that access is routine. These behaviours are subtle, but they can be highly effective because they exploit everyday interactions that staff rarely question.

The consequences, however, can extend far beyond the initial entry point. In high-security environments such as datacentres, laboratories and research facilities, an unauthorised person may reach assets, processes or intellectual property of significant value. There is also the potential risk to staff, who may be unaware that someone inside the area has not been verified.

Strengthening access security with the OV-102

Preventing tailgating requires a proactive approach that goes beyond traditional access control. While issuing staff access cards, fobs or biometric credentials is essential, these systems alone cannot distinguish whether more than one person has entered on a single authorisation. Organisations therefore increasingly rely on complementary technologies and practices. Infrastructure such as turnstiles can help regulate high-traffic areas by restricting entry to one person at a time. Live video monitoring assists in identifying tailgating as it occurs, supporting rapid intervention. People-counting technology provides automated alerts when the number of individuals entering does not match the number of valid credentials used. Alongside these tools, staff awareness and training remain vital, as many incidents stem from everyday behaviour rather than overt malicious intent.

To help organisations address these challenges more reliably, OPTEX’s anti-tailgating system – Accurance OV-102 – is designed for environments where even a brief lapse in access security could have serious consequences. Suitable for a wide range of high-security applications, the OV-102 uses advanced human-tracking and direction-determining technology to identify when more than one person attempts to move through a secured access point, whether deliberately or by accident. When such an event is detected, the system generates an immediate output, allowing security teams to intervene before unauthorised access occurs.

The OV-102, which can be seamlessly integrated with access control systems, also offers flexibility for different access scenarios. It can detect tailgating during entry, identify cross-entry when an unauthorised person attempts to enter as an authorised individual exits, and recognise multiple people lingering within the detection area. Its design supports varied installation environments thanks to adjustable detection areas, sensitivity settings and a door-cancel function that ignores door movement when required. 

A layered approach to secure access

Protecting high-security locations relies on a layered, intelligent approach. Although tailgating may seem like a small lapse, its impact can be significant. By combining sound access-control practices with technology designed to detect unauthorised movement, organisations can better protect their assets, ensure the safety of their staff and maintain confidence in the security of their operations.