Turnstiles are a great, but under used, tool for access control. The concept of a turnstile is simple, create a gateway that either allows access only in one direction, such as an “exit only” from a parking lot; or allows access for only one person at a time, either to count the number of persons entering, or to restrict access only to those with a pass or ticket.

Turnstiles can be grouped into three categories: mechanical, optical and video. Mechanical turnstiles physically prevent entry, while optical turnstiles provide guidance to security officers and receptionists. Video turnstiles simply record entry and exit. Each has its place in a security program.

Physical Access Control

As risk and threat increases, the need to better control access and egress increases.

Mechanical turnstiles typically use ratchet mechanisms to allow the rotation of the stile in one direction allowing ingress but preventing rotation in the other direction. They are sometimes designed to operate only after a payment has been made, usually by inserting a coin or token in a slot (such as in a subway or on a bus); or by swiping an electronically encoded access card.

Turnstiles can also used for counting the numbers of people passing through a gate, even where payment is not involved. Amusement parks use turnstiles to keep track of how many people enter and exit the park and ride each ride.

Airports use turnstiles to prevent “upstream” access. Airports have significant security requirements to make sure only people that have been through a security checkpoint are in the gate areas. The typical airport has a large volume of passengers traveling both in and out of its facilities. Turnstiles allow free and fast exit, while assuring that the exit cannot be used as an entrance. Some applications use revolving doors as an “exit only” passage.

One downside to mechanical turnstiles is a potential security risk. Turnstiles are regularly used to allow egress through a fence from parking lots. The concept is to allow unattended egress. The design of an external turnstile resembles a ladder, and if not installed properly, can be used to climb the fence. Attention needs to be paid to the area around, and especially above, the turnstile.

Invisible (Optical) Turnstiles

Optical turnstiles take the concept of a turnstile, and add technology. An optical turnstile is a turnstile in theory, but has no physical means to prevent access. An optical turnstile is a “lane” through which people pass. Optical turnstiles operate much like regular mechanical turnstiles, except that they rely primarily on electronic (infrared) beams, and audible/visual interfaces to control entry. Rather than physically restraining a person, the optical turnstile uses sounds and lights to alert others to attempted entry by unauthorized individuals.

An optical turnstile only works in conjunction with a security officer or receptionist overseeing the entrance. When presented with an access card, the optical turnstile generally lights up (green for authorized, red for unauthorized) and alerts with a pleasant “ding” for authorized, or an annoying buzz for unauthorized. While access is not physically restricted, it is the job of the turnstile to alert the security officer or receptionist to an unauthorized access attempt.

Optical turnstles have limited use, but are especially suited for settings where design and aesthetics are important, such as corporate or office building lobbies. The application is perfect for high rise buildings with a single path through the lobby and staffed reception.

Several companies have been in the turnstile business for decades. Perey Turnstiles (www.turnstile.com) has been in business since 1913. Perey designs, manufactures and sells tripod-turnstiles, Drop-Arm-Turnstiles, Optical-Turnstiles, gates and other “crowd management, admissions and access control mechanisms.”

For more than fifty years, Alvarado Manufacturing (www.alvaradomfg.com) has been involved with the manufacturing and design of security turnstiles, including mechanical, optical and a variety of solutions for almost any application. Alvarado security turnstiles are used at tens of thousands of locations in the U.S. and abroad.

People Counting Systems

Biodata (http://www.videoturnstile.com) offers a unique technological approach, the video turnstile people counting system. The system lets shopping centers, galleries, banks, nightclubs, libraries, retail outlets or any facility record the number of people entering and leaving the premises.

The person counting system uses overhead security video cameras to track people entering and leaving a building through a pre-defined space. The video turnstile unit detects, counts and records entries and exits. The system displays in Windows software, and offers a clear visual verification.

Users can watch the video and see marker lines flash when the system detects someone crossing the threshold. The system is automated, and many entrances can be monitored simultaneously. Counts are regularly downloaded to a PC running Windows, and people counts can be exported to almost any third-party Windows software, including Excel and Access. The video output from the overhead camera can is overlaid with markers to show when a person is detected crossing a pre-defined transit zone.   

SIDEBAR: Jack Hanna, Flamingo Stuck in Turnstile

The Associated Press recently reported a tight squeeze for the animal aficionado and his associates.

Animal expert Jack Hanna and an 11-month-old flamingo became trapped while trying to squeeze through an airport security turnstile. It took firefighters to finally get the flamingo out.

Hanna, the director emeritus of the Columbus Zoo and a frequent guest on nationally televised talk shows, was returning from a zoo fundraiser with a mongoose, a small leopard and the flamingo. Three other people were with them.

The entourage arrived at the Ohio State University Airport just after midnight Sunday to find the terminal closed. The only way to leave the tarmac was through a 10-foot-tall metal turnstile with several horizontal bars - not the easiest exit to squeeze through when you’re traveling with boxed-up animals, Hanna said.

“I never thought about the crate being square and the turnstile being round,” he said.

Hanna, 60, pushed the flamingo’s 2-foot-by-3-foot compartment into the turnstile, then continued pushing while straddling the crate.

“I was stuck like a worm. My eyes were as big as grapefruits,” he said. “I can’t describe the feeling in my stomach. I can’t move up or down. The bars are on your face.”

Hanna said he eventually squirmed free, leaving the flamingo still wedged inside and everyone else trapped on the tarmac. He then walked to a nearby fire station for help. It took three firefighters to hoist the flamingo’s crate up and out of the turnstile, he said.

Columbus fire department logs show the firefighters arrived at the airport at 12:30 a.m. for a “flamingo rescue,” spokeswoman Kelly McGuire said.

Hanna joked that the next time he flies through the airport, the biggest animal he’ll bring is a gerbil.

(Copyright 2007 by The Associated Press. All Rights Reserved.)