Two questions come up on almost every entry control project: will it stop people sneaking in behind someone else, and will it get everyone out safely if there is a fire? Both are fair, and both deserve a clear answer.
What is tailgating?
Tailgating is when someone who has not been authorised follows a person who has, through a controlled entrance. It is the most common weakness in any access control system. A card reader on its own cannot prevent it, because the door cannot tell how many people have walked through on one swipe.
Detection versus prevention
Different products take different approaches:
- Prevention: full height and tripod turnstiles physically allow one person at a time. Tailgating is very difficult.
- Detection: speed lanes use sensors to track each person through the lane. If two people try to pass on one credential, the gate can close, sound an alarm or alert staff.
- Verification: adding PIN, biometrics or a receptionist improves confidence in who is passing through.
No entrance is perfect. A speed lane with an unattended reception is a deterrent and a detection device, not a locked door. The more serious the risk, the more important it is to combine the product with staff presence and other controls.
What happens in a fire?
People must be able to leave quickly and without obstruction. That means entry control equipment that lies on an escape route has to be designed so it releases, or provides a clear route, when the fire alarm operates.
- Fire alarm interface: speed gates can be connected to the fire alarm so that the wings open automatically. This has to be designed and tested, it does not happen by default.
- Fail-safe or fail-secure: in a power cut, a gate can be set to open (fail-safe) or remain locked (fail-secure). For escape routes, fail-safe behaviour is normally expected.
- Back-up power: some gates stay operational for a period on battery before moving to their default position.
- Alternative exit routes: a staffed or emergency door beside the lanes is often part of the fire strategy.
Who signs this off?
The behaviour of entry control in an emergency should be agreed with whoever is responsible for the building’s fire strategy, usually the fire risk assessor, a fire engineer or the building control body. Powered pedestrian doors and gates are commonly assessed against recognised safety standards, and your installer should be able to show how the design meets them.
Questions to ask your supplier
- How does the equipment detect or prevent tailgating and how well has it been proven in similar sites?
- How does it behave in a fire alarm and in a power failure?
- Is it connected to the fire alarm panel and who tests that link?
- Where do wheelchair users and people with luggage pass?
- Who maintains it and how quickly can they attend?
For help choosing, see our turnstiles and speed lanes page, or read the comparison in turnstile or speed lane.
Frequently asked questions
What is tailgating?
Tailgating, sometimes called piggybacking, is when an unauthorised person follows an authorised person through a controlled entrance without presenting their own credential.
Do speed gates open when the fire alarm goes off?
They can be set up to, but only if the gates are connected to the fire alarm system and designed that way. It is a specific design requirement, so confirm it at the specification stage.
What happens to a turnstile in a power cut?
It depends on how it is configured. Gates can be set to open, to stay locked or to hold their position for a period on back-up power, and the right choice should come from your fire strategy.