How many turnstile lanes do you need? A throughput sizing guide

Start with peak flow, not headcount

The number that sizes an entrance is not how many people work in the building. It is how many arrive in the busiest fifteen minutes.

A 1 200-person office does not present 1 200 people to the lobby. It presents perhaps half of them between 07:45 and 08:15 and the rest across the morning. A 600-person mine shift, by contrast, presents almost everybody inside ten minutes, twice a day, because the shift change is fixed. Same headcount, completely different entrance.

• Count arrivals in the busiest 15 minutes, not across the day.
• Shift-driven sites (mines, factories, call centres) peak far harder than office sites.
• Add contractors, visitors and deliveries — they use the same lanes.
• If the canteen or smoking area is outside the line, people cross the entrance several times a day, not twice.

The calculation

Divide peak arrivals per minute by the sustained throughput of one lane, then round up. That gives the working lanes. Standby and accessible lanes are added on top — they are not part of the throughput.

Worked example: 600 people over a 15-minute shift change is 40 people/min. Through full-height turnstiles at about 18/min per lane, that is 40 ÷ 18 = 2.2, rounded up to 3 working lanes. Add one standby lane for servicing and one wide accessible lane, and the entrance is 5 lanes.

Working lanes only. Add one standby lane and one accessible lane to each figure.

The two lanes everybody forgets

The standby lane. A lane will at some point be out of service — a reader failure, a service visit, a damaged wing. If the entrance was sized with no slack, that day becomes a queue out the door. One spare lane is the cheapest insurance in the design.

The accessible lane. A wheelchair user, a stretcher, a pallet trolley and a visitor with luggage all need a wide gate. It must sit on the secure line — not be a door beside it that quietly undoes the whole entrance — and it should be controlled by the same system.

Things that quietly halve your throughput

The published rate of a lane assumes an authorised user who knows exactly what they are doing. Most sites do not get that on day one.

• Slow credential reads. A fingerprint match on a dirty hand takes several attempts. Where hands are wet, gloved or dirty, plan for a card or facial reader instead — and ask for the read time.
• Unfamiliar users. Visitor-heavy entrances run far slower than staff entrances. Separate the two flows if you can.
• Bags and trolleys. A lane that is fine for a person is not fine for a person with a crate. Size the accessible lane for the goods, not only the wheelchair.
• Tailgating enforcement. Strict anti-passback and one-person detection slow a lane down. That is the trade — budget throughput for the enforcement level you actually intend to run.
• Both directions at once. A bidirectional lane does not give you double capacity. If entry and exit peak together, count them together or split the lanes.

Sanity-check the queue, not just the lane

Three lanes at 18 people/min clears 54 people a minute, so 600 people take about eleven minutes to get in. That means the last person in the queue waits eleven minutes — is that acceptable for that site, in that weather, in that direction?

Then check the space in front of the lanes. An entrance that meters people correctly but has nowhere for them to stand pushes the queue into a road or a stairwell. The turnstile line and the queueing area are one design.

When you have a figure, send us the numbers — peak arrivals, window, direction and security level — and we will confirm the lane count and the right product line for the site.

Common questions