When estimating the number of turnstiles required for an application, a major factor to
consider is rate of throughput…which is commonly defined as the number of people passing
through a turnstile per minute.
Controlled Access vs. Free Access
Controlled access requires a user to present a credential. When access is controlled, the
access system provides a signal to the turnstile to either open or unlock. Free access (often
used in exiting) allows the user to pass without presenting a credential. With free access,
the turnstile is either constantly unlocked or opens automatically without a signal from the
access system. Free access will have a higher rate of throughput than controlled access.
Access System Response Time
Access systems check the presented credential and then provide a signal to the turnstile to
open or unlock if the credential is valid. The time it takes an access system to check
credentials and provide a signal to the turnstile will vary between systems. Even access
systems with fast response times may periodically have a slower response. The slower the
access system response time, the slower the rate of throughput.
Card Reader/Access Device Type
Rate of throughput will also vary depending on the access device used. A longer-range
proximity reader, which allows a user to keep their access card in their wallet or purse during
the access process, will provide a faster rate of throughput than a card that has to be
removed to be read. Use of a proximity reader that also requires the user to enter an access
code will decrease the rate of throughput. A biometric device (depending on the device and
application) can decrease the rate of throughput substantially.
Human factors can also substantially affect throughput. As with any new technology, there is a
“learning curve” for users when initially using new equipment. User training is important for
system acceptance and smooth operation.
Waist high turnstiles (such as the EDC) will generally have a higher throughput rate than full
height turnstiles (MST or CPST) due to the shorter distance a user will travel when going
through the device.
Barrier optical turnstiles (SU3000, SU3500 or SU5000) will generally have the greatest rate of
throughput since the equipment stacks credentials (meaning multiple users can present his/
her card one after the other without the panels cycling)
Full Height: 20 – 30 people per minute
Waist High: 25 – 40 people per minute
Barrier & Barrier Free Optical: 45-60 people per minute
Assuming use of a proximity card and a 250 millisecond access response time (1/4 second),
under ideal conditions, a good rule of thumb is a throughput rate of 1-2 seconds for optical
and waist high turnstiles and 3-4 seconds for full height turnstiles.
To determine the number of turnstiles sufficient for a facility, the following formula can be
used: (Number of Patrons / time allotted) / rate of throughput = number of turnstiles required
Assuming a 2 second throughput rate (30 people per minute per turnstile), it would take
approximately four devices to allow 4000 patrons to enter in a 30 minute time span.
(4000 ÷ 30) ÷ 30 = 4.44