Speed Gate Lane Sizing for NZ Buildings: A Practical Guide

How many speed-gate lanes does a building need? Start with the busiest five minutes of pedestrian demand, divide it by a defensible effective passage rate per lane, then adjust for queues, direction, accessibility and failure scenarios. A worked example below explains why a theoretical minimum is not always a resilient final layout.

Start with peak demand, not the building's population

The number of people employed in a building is not the same as the number who arrive during its busiest few minutes. A building with 500 occupants may experience concentrated arrivals before the working day, after public transport services, during a shift change or at the end of a major event. Entrance design should therefore begin with observed arrivals in short intervals, preferably at five-minute resolution. Separate entry and exit movements, visitors and staff, and any entrance shared with deliveries or reception. A single daily average can hide the queue that actually drives lane requirements. If no counts exist, use a transparent planning scenario and commission a site survey before specifying hardware.

Build a usable five-minute arrival profile

Record how many people reach the controlled line in each five-minute interval for several representative busy days. Include the time of day, direction of travel, whether users have their credentials ready, and any interruptions. A spreadsheet with one row per interval is sufficient for a first pass. For a new development, estimate arrival profiles from tenancy, shift patterns, lift discharge and the surrounding transport network, marking every input as an assumption. Consider simultaneous queues from a lift lobby or public footpath. The design question is not simply whether the gate can open quickly, but whether the whole approach can process arrivals without obstructing circulation or compromising emergency movement.

Convert gate cycle time into practical lane capacity

Manufacturers may publish an ideal passage rate under specific test conditions. Actual capacity also depends on card presentation, reader response, door movement, hesitation, bag handling, pedestrian spacing and operator intervention. For early planning, use a deliberately conservative effective rate instead of treating the catalogue maximum as guaranteed throughput. For example, assume 20 completed passages per minute through one conventional lane after allowing for real user behaviour. At that assumed rate, one lane could process 100 people in five minutes. This is an illustrative engineering calculation, not a tested performance figure for any particular FERN360 model. Obtain the model's documentation and validate the effective rate during commissioning.

Worked example: compare arrivals with capacity

Suppose an office entrance receives 240 people in its busiest five-minute period, with an assumed effective capacity of 20 people per minute per lane. Demand averages 48 people per minute during that period. Dividing 48 by 20 gives 2.4 lanes, so the theoretical minimum is three operating lanes. That calculation leaves little allowance for interruptions, uneven bursts or one lane being temporarily unavailable. Four lanes would provide a larger planning margin, but the final choice depends on acceptable queue length, physical layout, bidirectional flow and access arrangements. Do not convert this illustration into a universal rule: repeat it with measured demand and the exact gate configuration.

Model queue build-up and recovery

A queue forms whenever arrivals temporarily exceed service capacity. Consider a site with 55 arrivals per minute for two minutes and three lanes each clearing an assumed 20 people per minute. Aggregate service capacity is 60 per minute, so no queue builds under those simplified steady assumptions. If one lane is unavailable, service falls to 40 per minute and the two-minute surge creates an estimated backlog of 30 people. When full capacity resumes and arrivals drop to 25 per minute, the surplus clearing capacity is 35 per minute, so that theoretical backlog clears in under a minute. Actual results vary because arrivals are irregular and passengers do not distribute perfectly between lanes.

Allow for exit, visitors and changing direction

Entrance counts must be split by direction. At some buildings the morning peak is mainly inbound and the afternoon peak mainly outbound. At others, public-facing services, mixed-use tenancies and car park connections create two-way demand throughout the day. Confirm whether each proposed gate can reverse direction under the intended access-control logic, and whether staff can manage that change safely. A bidirectional lane is not equivalent to two lanes operating simultaneously in opposite directions. Visitor credential checks, reception screening, courier access and after-hours operation may also require a separate workflow. Reserve enough clear floor area for waiting people before selecting the quantity of cabinets.

Accessibility is a design input, not an afterthought

Accessible circulation should be planned from the first sketch. Check the applicable New Zealand Building Code obligations, consent documents and accessibility requirements with the project designer rather than assuming that an advertised 900 mm gate passage resolves every issue. Consider wheelchairs, mobility aids, prams, luggage and accompanied users, as well as the position of readers and the time allowed for crossing. A wide lane may need different control logic and sight lines from standard lanes. Users should not be forced into an unsuitable side entrance or an approach obstructed by queuing. Emergency egress, fire-alarm interface and security release requirements must also be confirmed for the actual building.

Check the complete entrance geometry

A lane schedule needs to show more than cabinet width. Plot the clear approach, turning space, gate swing or retracting envelope, security line, reception desk, lift lobby and adjacent doors. Keep the accessible route usable when ordinary queues form. Avoid placing readers where people must stop in the swing path, and allow for users who pause after presenting a credential. For glass barriers or optical sensors, consider sunlight, reflective finishes, trolley movements and cleaning procedures. Use a dimensioned layout showing service access and cable routes rather than fitting the maximum number of cabinets into a narrow gap.

Choose a product configuration only after the calculation

FERN360 speed-gate configurations can be useful candidates for commercial pedestrian access control, but the correct gate width, cabinet arrangement, direction logic and integration vary by model. A published manufacturer passage rate should be checked against the exact model, reader arrangement and intended usage. Compare standard passage lanes with a suitably designed accessible lane and account for how common cabinets form adjacent channels. Review turnstiles and swing gates when the site needs a different security boundary or passage behaviour. Product identity and compatibility matter more than selecting an apparently fast model from a photograph.

Commission the design against actual behaviour

After installation, test with representative credentials and a realistic sequence of users. Measure typical and busy passage rates, failed reads, hesitation points and recovery from lane faults. Check power loss behaviour, fire-alarm release, obstruction detection, tailgating alerts, directional changes and operator overrides against the approved cause-and-effect schedule. Observe what happens when a queue reaches the lobby edge and when an accessible lane is occupied for longer than usual. Record the as-built dimensions, access-control settings, maintenance access and the procedures for temporarily removing a lane from service. Update the capacity assessment if measured performance differs materially from the assumption.

Specify and review the entrance as a system

A useful procurement brief should include arrival counts, peak interval, acceptable queue length, directions, accessible route, gate configuration, reader platform, security functions, emergency interfaces, finish, service access and testing acceptance criteria. Ask the integrator to state the assumed effective throughput and how it will be validated. The professional goal is an entrance that works during the busiest real operating conditions, not a headline maximum speed. For product comparisons, review the relevant turnstile, speed-gate and swing-gate guide, the pedestrian access design guide and the access control range before requesting a project-specific specification.

Frequently Asked Questions

How many speed-gate lanes does an office need?

Count peak five-minute arrivals, select a justified effective throughput per lane and calculate a theoretical minimum, then check queues, faults and accessibility. Building occupancy alone is not enough.

Can a bidirectional speed gate count as two lanes?

No. One physical lane generally cannot process two opposing streams simultaneously. Check the model's directional operating logic and the expected peak in each direction.

Should an accessible gate be included in capacity calculations?

Yes. Plan an accessible circulation route from the outset and check the actual gate configuration, approach, operation and local compliance requirements rather than assuming the product's nominal width is sufficient.

Are catalogue throughput figures guaranteed in a real lobby?

No. Published rates depend on conditions. The installed system's effective rate should account for credentials, hesitation, interruptions and the precise reader and gate configuration.

What should be tested during commissioning?

Test representative peak passages, credentials, fault recovery, emergency release, accessible operation, directional control, obstruction response and the actual queue behaviour.