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 breach 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.
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
- Approximate cost: |£2,000 to £3,500 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.
- Comments: Good choice for visitor lobbies or employee entrances that are constantly attended by a security officer and where cost is a consideration.
FULL-HEIGHT MECHANICAL TURNSTILE
- Approximate cost: £3,500 to £5,000 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.
- Comments: Good choice for commercial and industrial facilities where security and cost considerations are more important than appearance.
- Approximate cost: £11,000 to £15,000 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, provides little or no physical barrier, must be used at an entrance manned by security guard, relatively high “false alarm” rate.
- Comments: Good choice for use in manned building lobbies where aesthetics prevent the use of a half-height manual turnstile.
SECURITY REVOLVING DOOR
- Approximate cost: £22,000 to £38,000 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.
- Approximate cost: £22,000 to £38,000 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: Very expensive, relatively slow, cannot support large volumes of traffic, 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
- Approximate cost: £3,000 to £5,000 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.
- 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.
Other Anti-Tailgating Systems
There are several new anti-tailgating detection systems on the market. These include closed-circuit television camera systems equipped with video analytics software, and machine vision sensors that use infrared imaging technology. Both of these systems “look” at the entrance point and use computer software to detect tailgaters. Once a tailgater is detected, an audible alarm is activated to alert the security guard.
While this new technology looks promising in the long run, it is our opinion that these systems are still too new and unproven for use in most applications.
Have additional questions about the prevention of tailgating? Please contact us.