The origin of the word turnstile is ‘stile’ which in olden days was a series of steps (general wood or stone) that allowed people, but not livestock, to climb over a fence or a wall. An early turnstile was a wooden movable gate (as shown below and to the left *) which allowed people to pass through a fenced in area one at a time, while again keeping livestock out.
Today’s full height turnstile barrier gates are an effective tool to control or restrict human traffic entering a business, school, high security, military or governmental location. They allow one person at a time to enter a fenced in area or doorway.
Shown above is a full height combination employee access control turnstile barrier gate and fully Americans with Disability Act (ADA) compliant doorway access for persons with disabilities. Note the card reader mounted on a pedestal base in the foreground.
A person enters an open section (wing, compartment, etc.) of the turnstile after entering some type of authorized access control credentials. The locking mechanism is released and allows access to the other side when the person manually pushes an arm (or a stile) and walks a one-third circular rotation. At this point, the turnstile again locks in place until another authorized credential is presented.
Shown to the right is an indoor BoonEdam TurnLock turnstile which separates a work area from the lobby. Employees with authorized credentials can move from the lobby into the work area while visitors and truck drivers can not access it.
Turnstiles may operate in either a single direction or can be bi-directional. Locking and unlocking can be controlled through access control software. This software also accumulates data as to who is coming and going and at what times and dates. These may be programmed or can allow free access to management and other authorized (i.e. security) personnel.
Pictured below is an outdoor tandem (or two-way) employee turnstile manufactured by Alvarado.
When an emergency occurs such as a fire, turnstiles can be unlocked to allow free egress via a relay from the fire alarm system. Security personnel and guards may also release turnstiles manually. The law requires free exit to leave.
Turnstiles are also referred to as baffle gates, ‘cheese graters’, revolving doors, and can also be spelled turnstyle. I have even seen in print in two words – turn stile.
* Image © Copyright Gillie Rhodes and licensed for reuse under this Creative Commons Licence. The title has been changed solely to reflect the scene name and alt tag.