Choosing entrance control: tripod, full-height, speed gate or swing gate

Entrance control equipment addresses several quite different failures, and the right product for one is the wrong product for another.

If the failure is an unauthorised person entering behind an authorised one, you need tailgating control, and the question becomes whether an alarm is sufficient or whether physical prevention is required. If the failure is an unauthorised person entering an unstaffed opening, you need a barrier that cannot be climbed or vaulted. If the requirement is an accurate headcount for mustering or for time and attendance, you need a device that guarantees one passage per authorisation and reports reliably, and the physical barrier may matter less than the event data.

Write that sentence into the specification before the equipment schedule. A brief that says the lobby shall be secured leaves the decision to whoever is pricing it; a brief that says no passage shall be possible without an individual authorisation, and any attempt shall be physically prevented rather than reported, has already narrowed the field to two families.

Tripod turnstiles use a waist-height rotating arm assembly. They are compact, inexpensive and robust, and they enforce one passage per authorisation at the arm. They do not prevent a person from climbing over or crawling under, which makes them appropriate where supervision is present or where the purpose is orderly counted flow rather than denial — stadium concourses, industrial time recording, worker accommodation gates.

Full-height turnstiles use a rotor running floor to soffit inside a cage. They are the only family in common use that physically prevents circumvention at an unstaffed opening, which is why they appear on site perimeters, substations, yards and accommodation compounds. The trade-offs are real: they are slow for groups, they cannot pass goods, trolleys or wheelchairs, and they need an adjacent controlled gate for anyone or anything that cannot use the rotor. Rotor geometry matters too — a three-arm rotor gives a wider, more comfortable compartment, while a four-arm rotor gives smaller compartments and tighter single-person control.

Speed gates, sometimes called optical turnstiles, use retracting or swinging glass barriers together with a sensor array along the lane. They give the best user experience and the highest sustained flow, and they detect tailgating well. What they do not do is physically prevent a determined person from pushing through or vaulting a barrier — that is a design characteristic, not a defect, and it is the reason speed gates are normally deployed within sight of a reception desk.

Swing gates, the wide lane at the end of a bank, exist for accessibility, luggage, trolleys and deliveries. They are the lowest-security element in any array and are almost always the route an attacker or an unbadged visitor takes, so they need the same credential requirement, the same monitoring and usually a camera.

Throughput claims in product literature typically describe free flow in one direction with pre-authorised users who do not stop. Real lanes carry a credential presentation, an authorisation round trip, a barrier opening, a human walking through and a barrier closing. The difference between the two is what produces a queue on the pavement at 07:45.

Size the lanes yourself. Take the number of people arriving in the busiest fifteen minutes, not the daily total. Convert to an hourly rate by multiplying by four. Establish the realistic cycle time per person in seconds, including credential read and authorisation — measure it on a sample of the actual credential and reader you intend to specify, because a card tap, a phone unlock and a face match are not the same transaction. Lane capacity per hour is 3,600 divided by that cycle time. Divide the peak hourly rate by lane capacity, then add margin.

Two pieces of margin are not optional. First, never design at theoretical capacity: queues grow without bound as utilisation approaches 100 percent, so size for roughly seventy to eighty percent. Second, add at least one lane beyond the calculation so that maintenance, a failed reader or a lane reversed for egress does not collapse the design.

Then put the burden of proof on the supplier. Require throughput to be stated for the specified credential type and authorisation path, and require it to be demonstrated during site acceptance testing with the real population, not with a technician walking through an unlocked lane.

The phrase anti-tailgating in a specification is almost always ambiguous, and the ambiguity is expensive. Detection means the equipment recognises a second body in the lane and raises an alarm; the person is already inside. Prevention means the second person is physically stopped.

Only a few arrangements actually prevent: a full-height rotor, an interlocked two-door portal where the second door cannot open until the first has closed and the compartment has been verified, or a lane with a barrier tall enough and a sensor arrangement fast enough to close on the second body. Everything else detects.

So the specification must say which is required, and what happens when the event occurs. An alarm with no defined response is not a control. State where the alarm annunciates, who acknowledges it, what the camera does, and whether the lane locks down. If detection is acceptable, say so plainly, and set the sensor performance expectation — including the false alarm rate you will tolerate for people carrying bags, walking close together or passing a child through.

Power operated pedestrian entrance control equipment — turnstiles, speed gates and swing lanes — falls under EN 17352, which sets safety in use requirements and test methods for exactly this equipment. It is a different standard from EN 16005, which covers power operated pedestrian doors, and from EN 12453, which covers power operated industrial, commercial and garage doors and gates. Specifications regularly cite the wrong one; naming EN 17352 correctly is a small edit that removes a whole category of argument at submittal stage.

Egress is where projects lose time. In the Kingdom, the Saudi Building Code governs — SBC 201 contains the means of egress requirements and SBC 801 is the Saudi Fire Code, with the 2024 editions in force since 1 July 2025 — and the Civil Defence authority having jurisdiction has the final say. Establish the egress position before the layout is fixed, not after the equipment is on site.

Whatever the route, specify the failure behaviour explicitly: what the barriers do on fire alarm, on loss of mains power, on loss of the access control network, and on manual release; whether battery backup is permitted to hold barriers closed; and the clear egress width available with the barriers in their released position. Drop-arm and collapsing-arm mechanisms on full-height units, and barrier retraction on speed gates, exist for this reason and have to be called out, not assumed.

Every bank needs a lane that a wheelchair user, a person with luggage and a delivery trolley can use, and that lane needs the same credential requirement as every other lane. It is the single most common gap between a security design and the way a building is used.

Specify the clear width against the project accessibility criteria, and specify an adjustable extended open time for that lane so that a slower user is not caught by a barrier sized for commuter flow. If the bank is full-height turnstiles, the accessible route is a controlled gate alongside, and it must be monitored — otherwise it becomes the default entrance for everyone.

The same applies to goods and contractors. If there is no defined route for a pallet truck, one will be improvised, and it will be a door propped open on the loading bay.

A lobby unit and a stadium gate are not the same product even when the datasheet is the same. Specify the environment rather than assuming it.

Outdoor and semi-outdoor installations need a stated ingress protection rating for the pedestal and for the reader housing, and they need optical sensor arrays that tolerate airborne dust — fine sand is the most common cause of nuisance tailgate alarms on exposed speed gates. Direct sun changes the picture again: enclosure interior temperature under solar gain, not shaded ambient, is the number that matters for electronics and for motor duty, so state an ambient range and require the supplier to confirm it for the enclosure.

Materials are a Saudi-specific decision. In coastal areas of the Eastern Province, grade 316 stainless steel is the sensible default for exposed housings and fixings, with 304 acceptable inland; powder coated mild steel outdoors will not survive. Ask for cycle life as a tested figure with the test conditions stated, and ask what is consumable — sensor lenses, barrier seals, rotor bearings — and what the lead time is for those parts in the Kingdom.

Finally, specify the integration honestly. State how the lane connects to the access control system, whether readers are mounted inside the pedestal, that reader to controller communications use OSDP rather than Wiegand, and what per-lane events must be reported: passage granted, passage denied, tailgate, forced, safety stop, and lane offline.

An entrance control clause is complete when it contains all of these:

• A statement of the failure being prevented: tailgating, unattended entry, or counted flow.
• Whether tailgating must be physically prevented or may be detected and alarmed — and the defined response to an alarm.
• Peak fifteen-minute arrival numbers, the assumed cycle time per person including credential read, the resulting lane count, and the design utilisation used.
• At least one spare lane beyond the calculated requirement.
• Throughput to be demonstrated at site acceptance testing with the specified credential and the real population.
• EN 17352 named as the safety reference for the entrance control equipment, with EN 16005 or EN 12453 cited only where powered doors or vehicle gates are in scope.
• Egress position agreed with the Civil Defence authority having jurisdiction under the Saudi Building Code, and the agreed arrangement recorded in the specification.
• Explicit failure behaviour on fire alarm, mains failure, network failure and manual release, plus the clear egress width in the released position.
• One accessible lane per bank, at the project clear width, with extended open time and the same credential requirement.
• A defined route for goods, trolleys and contractors.
• Environmental requirements: ingress protection rating, enclosure ambient temperature under solar gain, dust tolerance for sensor arrays.
• Material grades stated — 316 stainless in coastal Eastern Province locations — with consumables, tested cycle life and in-Kingdom spares lead time.
• Integration requirements: OSDP reader communications, per-lane event reporting, direction control and free-exit modes.