Turnstiles are used at a wide variety of settings, including stadiums, amusement parks, mass transit stations, office lobbies, airports, ski resorts,[note 1] factories, power plants and casinos.
From a business/revenue standpoint, turnstiles give an accurate, verifiable count of attendance. From a security standpoint, they lead patrons to enter single-file, so security personnel have a clear view of each patron. This enables security to efficiently isolate potential trouble or to confiscate any prohibited materials. On the other hand, physical barriers become a serious safety issue when a speedy evacuation is needed, requiring emergency exits that bypass any turnstiles.
Persons with disabilities may have difficulties using turnstiles. In these cases, generally a wide aisle gate or a manual gate may be provided. At some locations where luggage is expected, a line of turnstiles may be entirely formed of wide aisle gates, for example at Heathrow Terminals 2 & 3 Underground station.
Turnstiles often use ratchet mechanisms to allow the rotation of the stile in one direction allowing ingress but preventing rotation in the other direction. They are often designed to operate only after a payment has been made, usually by inserting a coin or token in a slot; or by swiping, tapping, or inserting a paper ticket or electronically-encoded card.
Turnstiles are often used for counting the numbers of people passing through a gate, even when payment is not involved. They are used extensively in this manner in amusement parks, in order to keep track of how many people enter and exit the park and ride each ride. The first major use of turnstiles at a sporting venue was at Hampden Park in Glasgow, Scotland
