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Turnstile

A turnstile, also called a baffle gate or turnstyle, is a form of gatewhich allows one person to pass at a time. It can also be made so as to enforce one-way traffic of people, and in addition, it can restrict passage only to people who insert a coin, a ticket, a pass, or similar. Thus a turnstile can be used in the case of paid access (sometimes called afaregate or ticket barrier when used for this purpose), for example to access public transport, a pay toilet, or to restrict access to authorized people, for example in the lobby of an office building.
History
Turnstiles were originally used, like other forms of stile, to allow human beings to pass while keeping sheep or other livestock penned in. The use of turnstiles in most modern applications has been credited to Clarence Saunders, who used them in his first Piggly Wiggly store.
Applications
Turnstiles are used at a wide variety of settings, including stadiums, amusement parks, mass transit stations, office lobbies, airports, ski resorts, 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 atHampden Park in Glasgow, Scotland.[citation needed]
Types
Waist-high
A turnstile used in fairs, attractions, and arenas. The user inserts a ticket or pass into the slot, from which a barcode is read; if access is to be granted, a sensor determines the speed with which the user passes through, and sets the electric motor to turn the turnstile at the corresponding speed. Sometimes also referred to as "half-height" turnstiles, this fixed arm style has traditionally been the most popular type of turnstile. There are many variations of this style available, including one which is designed to be accompanied by a matching ticket box, and one with a ticket box built in. Some styles are designed to allow entry only after a payment (actual coins and tokens) are inserted,while others allow access after a valid barcode is electronically read. A disadvantage to this type is people can "jump the turnstile"; as happens commonly on the Moscow Metro and other mass transport systems in Russia.
Optical
Optical turnstiles are an alternative to the traditional "arm"-style turnstile and are increasingly used in locations where a physical barrier is deemed unnecessary or unaesthetic. Optical turnstiles generally use an infrared beam to count patrons and recognize anyone attempting to enter a site without a valid entry pass.
Drop arm optical
The drop arm optical turnstile is a combination of the security of a tripod or barrier turnstile and a fully optical turnstile. The lanes can have either single or double arms. When access is granted the arms drop into recesses in the cabinet. Once the arms drop out of the way, the turnstile functions as a fully optical turnstile.
Full-height turnstiles
The full-height turnstile is a larger version of the turnstile, commonly *-foot (2.1 m) high, similar in operation to a revolving door, which eliminates the possibility (inherent in the waist-high style) of anyone jumping over the turnstile. However, this type of turnstile functions differently than a revolving door, in that it often does not allow someone to come in as someone else goes out. It is also pejoratively known as an "iron maiden", after the torture device of the same name, or "high-wheel".[2] It is sometimes called a "Rotogate", especially in Chicago, where it is used at unstaffed exits of Chicago 'L' stations, and is also used at many New York City Subway stations. In Europe, however, "Rotogate" refers to a different kind of gate that is not a turnstile.
There are two types of full height turnstiles, High Entrance/Exit Turnstile (HEET) and Exit-Only. The difference between them is that HEET turnstiles can rotate in both directions thus allowing two-way traffic, while exit-only turnstiles can only rotate in one direction thus allowing one-way traffic. Exit-only turnstiles are commonly used in mass transit stations to allow passengers to exit the system without interfering with those entering. Exit-only models are also used at enclosed areas such as theme parks, zoos, or amusement parks, to allow visitors to leave, while denying admission to those who have not paid.