The Problem of Tailgating

One of the biggest weaknesses of automated access control systems is the fact that most systems cannot actually control how many people enter the building when an access card is presented. Most systems allow you to control which card works at which door, but once an employee opens the door, any number of people can follow behind the employee and enter into the building. Similarly, when an employee exits the building, it is very easy for a person to grab the door and enter the building as the employee is leaving.

This practice is known as "tailgating" or "piggybacking". Tailgating can be done overtly, where the intruder makes his presence known to the employee. In many cases, the overt "tailgater" may even call out to the employee to hold the door open for him or her. In these cases, good etiquette usually wins out over good security practices, and the intruder is willingly let into the building by the employee.

Tailgating can also be done covertly, where the intruder waits near the outside of the door and quickly enters once the employee leaves the area. This technique is used most commonly during weekends and at nights, where the actions of the more overt tailgater would be suspicious.

Solutions To The "Tailgating" Problem

First, recognize that the tailgating problem is probably the biggest weakness in your security system. This is particularly true at doors that handle a high volume of employee and visitor traffic. Many security managers spent a lot of time worrying about unauthorized duplication of access cards and computer "hackers" getting into their security system over the network. It is far more likely that someone who wants access to your facility will simply "tailgate" into the building rather than using one of these more exotic methods to breech your security.

The practice of overt tailgating can be reduced somewhat through employee security awareness training. If employees are frequently reminded of the tailgating problem, they are less likely to let a person that they do not know into the building deliberately.

It is difficult to overcome the problem of covert tailgating through employee security awareness alone. While it would be possible to ask employees to wait at the door until it locks after they pass, it is probably not likely that this procedure would be followed except under the most extreme circumstances.

The problem of covert tailgating can usually only be reliably solved through the use of special "anti-tailgating" devices.

"Anti-Tailgating" Devices

To minimize the problem of tailgating, the security industry has created a number of "anti-tailgating" devices. These devices include mechanical and optical turnstiles, security revolving doors, security portals, and doorway anti-tailgating devices.

The essential function of each of these devices is that they permit only one person to enter or leave the building at a time. They either do this by providing a physical barrier that only allows one person to pass, or electronically by providing sensors that detect when a person attempts to tailgate in, or when more than one person tries to enter using the same card.

The following is a brief summary of each of the common types of anti-tailgating devices:

HALF-HEIGHT MECHANICAL TURNSTILE

Description: Rotating mechanical barrier arms installed at waist height prevent passage through opening. Electrically-controlled, using valid access card causes arms to unlock allowing passage of one person. Turnstile can be controlled in both directions, or allow free-passage in one direction.

Approximate cost: $5,000 to $7,000 USD per opening.

PROS: Lowest cost anti-tailgating device, readily accepted by most users, relatively unobtrusive, well-proven and reliable.

CONS: Can easily be climbed over or under, requires separate door or gate for emergency exit and for handicapped users, easily defeated by knowledgeable intruder, can be somewhat noisy when operated.

Comments: Good choice for use at visitor lobbies or employee entrances where cost is a consideration. Works best when turnstile can be observed by security officer or receptionist to allow detection of people climbing over or under the device.

FULL-HEIGHT MECHANICAL TURNSTILE

Description: Rotating mechanical barrier arms installed to prevent passage through opening. Extends from floor to height of approximately eight feet. Electrically-controlled, using valid access card causes arms to unlock allowing passage of one person. Turnstile can be controlled in both directions, or allow free-passage in one direction.

Approximate cost: $6,000 to $9,000 USD per opening.

PROS: Provides good security at a moderate cost. Well-proven and reliable.

CONS: Obtrusive in appearance, requires separate door or gate for emergency exit and for handicapped users, lacks sophisticated anti-piggybacking detection features, can be somewhat noisy when operated.

Comments: Good choice for commercial and industrial facilities where security and cost considerations are more important than appearance.

OPTICAL TURNSTILE

Description: Consists of two freestanding pillars mounted on each side of opening. Equipped with electronic sensor beams that transmit between pillars. Passing though opening interrupts sensor beam and causes alarm unless valid access card has first been used. Sensor beams are connected to computer processor that detects when more than one person attempts to pass though opening on a single card. Turnstile can be controlled in both directions, or allow free-passage in one direction. Available with or without mechanical barrier arms and in a wide variety of styles and finishes.

Approximate cost: $30,000 to $35,000 USD per opening.

PROS: Aesthetically-pleasing appearance, accommodates handicapped users, does not require separate emergency exit, has sophisticated anti-piggybacking detection systems, provides good visual and audible cues to users.

CONS: Expensive, units without barrier arms provide no physical deterrent, must be used at an entrance manned by security guard, relatively high "false alarm" rate, some user training required to work effectively.

Comments: Good choice for use in manned building lobbies where aesthetics prevent the use of a half-height manual turnstile.

SECURITY REVOLVING DOOR

Description: Standard revolving door that has been specially modified for security use. Extends from floor to a height of approximately eight feet. Typically has multiple quadrants equipped with electronic sensors that detect number of people in each quadrant. Use of valid access card allows one person to pass through door, if more than one person attempts to enter, door sounds alarm and reverses to prevent entry. Door can be controlled in one or both directions.

Approximate cost: $80,000 to $95,000 USD per opening.

PROS: Provides best protection against tailgating and piggybacking, fast, handles high volumes of traffic, unobtrusive in appearance, provides energy savings when used at exterior entrances.

CONS: Very expensive, requires separate door or gate for emergency exit and for handicapped users, door cannot be used for loading/unloading of large objects, relatively high maintenance costs.

Comments: Good choice for use at unattended building entrances where appearance is important.

SECURITY PORTAL (also called "Security Vestibule" or "Mantrap")

Description: Consists of passageway with door at each end. Regular swinging doors or automatic sliding doors can be used. Passageway is equipped with sensors that detect total number of people present. Sensors can include electronic beams, floor mat switches, and weight detectors. Video cameras with analytic software can also be used (see video analytics below). To use, user enters passageway and closes door behind him. He then proceeds to second door, and uses access card to enter. If more than one person is present in passageway, portal sounds an alarm and prevents entry. Portal can be controlled in one or both directions.

Approximate cost: $50,000 to $80,000 USD per opening.

PROS: Provides good protection against tailgating and piggybacking, unobtrusive in appearance, accommodates handicapped users, does not require separate emergency exit, allows load/unloading of large objects.

CONS: Expensive, relatively slow, cannot support large volumes of traffic, some versions can have high maintenance costs.

Comments: Good choice for use at unattended building entrances with relatively low traffic volumes and for entrances into high security internal areas, such as computer rooms.

DOORWAY ANTI-TAILGATING DEVICE

Description: Consists of devices installed on each side of regular doorway. Equipped with electronic sensor beams that transmit between devices. Passing though opening interrupts sensor beam and causes alarm unless valid access card has first been used. Sensor beams are connected to computer processor that detects when more than one person attempts to pass though opening on a single card. Doorway can be controlled in both directions, or allow free-passage in one direction.

Approximate cost: $3,000 to $7,000 USD per opening.

PROS: Easy add-on to existing doors; provides good protection against tailgating and piggybacking, unobtrusive in appearance, accommodates handicapped users, does not require separate emergency exit, allows loading/unloading of large objects, relatively inexpensive.

CONS: Must be used at an entrance manned by security guard, does not provide good visual and audible cues to users, some false alarms.

Comments: Good choice for use at doorways with relatively low traffic volumes and where conditions do not permit the use of another type of device.

VIDEO ANALYTICS ANTI-TAILGATING SYSTEMS

Description: Consists of video cameras installed at doorway opening. Cameras are connected to a computer with special video analytics software that detects and analyzes people and objects at the door. System may use multiple cameras that allow precise determination of object size, height, and direction of travel. When used at single door, video analytics anti-tailgating systems work similarly to doorway anti-tailgating devices and sound alarm when more than one person attempts to enter through door after a valid access card has been used. Video analytics anti-tailgating systems can also be used with security portals to both sound alarm and deny access when more than one person attempts to enter.

Approximate cost: $10,000 USD per opening for single door system, $15,000 to $20,000 USD for security portal system.

CONS: Single door systems do not provide a physical barrier so must be used at an entrance manned by security guard, requires frequent user training to prevent false alarms, relatively expensive.

Comments: Popular choice for use at computer rooms and other high-security facilities.

Selecting the Right Anti-Tailgating System

Choosing the right anti-tailgating system is an important decision. You need to consider your overall level of security risk, your ability to provide security staff to monitor your entrances and respond to alarms, and your budget for initial purchase and ongoing maintenance of the anti-tailgating systems.

Have additional questions about the prevention of tailgating or the selection of the right anti-tailgating device? Please contact us.

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Published May, 2016