At what wind speed does outdoor use of aerial work platforms become a risk?

A sudden gust of wind at a height of 25 metres can tip over an aerial work platform, even if the rated load of the platform has not been exceeded. Wind load acts in addition to the weight of the person, tools and material and fundamentally changes the stability of the machine. For site managers using scissor lifts, articulating boom lifts or truck-mounted platforms outdoors, the question of the permissible wind speed is therefore not a minor matter but one of the central safety decisions before every outdoor job.

Under STN EN 280, mobile elevating work platforms are generally designed for a maximum wind speed of 12.5 metres per second - this corresponds to 45 kilometres per hour or force 6 on the Beaufort scale, commonly referred to as a "strong breeze". At this wind force, whole branches are already moving and using an umbrella becomes difficult - an easily understood reference point for site practice.

One limitation is important, however: 12.5 m/s is the design value most commonly used in the industry, but it is not a universal law. The actual permissible wind speed depends on the model and must be checked in the operating manual of the machine in question. Some machines, especially compact scissor lifts with a large wind-exposed area when the platform is extended, may specify lower limits. Anyone who relies blindly on the general guide value without checking the specific manual is taking an incalculable risk.

Since a precise anemometer is rarely to hand on site, the Beaufort scale helps with a quick on-site assessment. From force 4 (moderate breeze, approx. 20 to 28 km/h), thin branches already move noticeably, which can cause noticeable oscillation on aerial work platforms at great height. Force 5 (fresh breeze, 29 to 38 km/h) sets larger deciduous trees in motion. At force 6 (strong breeze, 39 to 49 km/h, corresponding to around 12.5 m/s), the critical limit for most aerial work platforms is reached. From force 7 (near gale) upwards, outdoor use of aerial work platforms is inadmissible without exception.

Anyone who regularly works outdoors should not rely on their own feel for the wind, but should make a local weather warning or a simple wind meter a fixed part of daily planning. Many modern site weather stations provide live values that can be compared directly with the Beaufort scale.

The stability of an aerial work platform is determined by the interplay of dead weight, load, outreach and wind-exposed area. While the load acts as a vertical force, the wind acts laterally on the structure - on the platform, the boom and the people in the basket. When calculating wind load, a wind-exposed area of 0.7 square metres per person is usually assumed, which is included in the stability calculation in addition to the area of the platform itself.

With articulating boom lifts, this effect increases with outreach: the further the boom is extended sideways, the greater the lever arm through which a lateral wind force acts on the machine's tipping point. For this reason, many manufacturers specify lower permissible wind speeds at maximum outreach than in the stowed position. Scissor lifts are less affected by this effect because their lifting movement is purely vertical, but here too the wind-exposed area increases continuously with platform height.

If a roto telehandler with a personnel basket is used as an aerial work platform, STN EN 280-2, which applies specifically to work platforms with load-handling devices, applies in addition to the basic standard STN EN 280-1. Details are summarised in the guide to EN 280. In practice, this means for wind assessment: the dynamic load moment control of modern machines takes into account not only the basket load but also the current outreach and tilt angle - parameters that come under additional pressure under wind. Older machines that only monitor the rated load provide no differentiated feedback here and should therefore be handled more cautiously in windy conditions.

If the permissible wind speed is exceeded during use, the platform must be lowered without delay and operation stopped - regardless of how far the current task has progressed. Continuing to work "until the next break" is not a justifiable option, because gusts can briefly be well above the average value, even if the mean wind speed still appears to be within the permissible range. Site managers should define this stopping point at the planning stage so that the decision in the moment does not depend on the individual judgement of the operator under time pressure.

Wind speed and stability are not an isolated topic but belong in every risk assessment carried out before an aerial work platform is used outdoors. In addition to the wind forecast for the day of use, this also includes assessing the surroundings: building edges, passages between high-rise buildings or open areas can create local wind amplification well above the general weather forecast. If you are unsure how to systematically include wind load in your own risk assessment, the guide to inspections and tests of lifting equipment and machine documentation explains the organisational framework and which inspection and documentation obligations apply to each platform type.

For permanently wind-exposed locations - such as high-rise roofs, bridges or free-standing facades - it is worth looking at the wind-exposed area when choosing the machine. More compact diesel scissor lifts with a smaller platform area offer less surface to the wind than large models with extended platform decks. Details of the available diesel rough-terrain scissor lifts are summarised in the corresponding guide. For articulating boom lifts, we recommend consulting the Luibl Rental team about the specific wind class of the model in question, especially for jobs with expected high outreach.

At what wind speed must the use of an aerial work platform be stopped? The usual industry limit is 12.5 m/s (45 km/h, Beaufort 6). The actual permissible value for the specific machine is stated in the operating manual and may be lower.

Does the wind limit also apply indoors? No, the wind load limit applies exclusively to outdoor use. Indoors, this hazard does not apply, although other factors such as draughts through open doors should be considered in individual cases.

How can I estimate the wind speed on site without a measuring device? The Beaufort scale offers practical reference points: if whole branches are already moving and using an umbrella becomes difficult, force 6 and thus the critical limit has usually been reached.

Does the permissible wind speed change with the platform's outreach? Yes, with articulating boom lifts the permissible wind speed often decreases with increasing lateral outreach, as the lever arm for the wind force increases. The manufacturer's specifications are decisive here.

Does the same wind limit apply to roto telehandlers with a personnel basket as to conventional aerial work platforms? In principle yes, but STN EN 280-2 for load-handling devices also applies. The dynamic load moment control of modern machines takes wind influence into account indirectly via outreach and tilt angle.

Questions about the right machine for wind-exposed locations are answered by the Luibl Rental team during office hours, Mon-Fri, 08:00-17:00.

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