Wind, weather and crane work — limits you must know

One of the most dangerous moments on a terminal is not necessarily the heaviest load but the most wind-sensitive. An empty container, a flat rack or a large, flat object can behave like a sail when hanging freely in a crane and a sudden gust can make the load uncontrollable in a split second. Wind is therefore one of the factors most often underestimated in lifting work.

§Why wind is a hazard when lifting

The larger the surface area a load has relative to its weight, the more the wind affects it during lifting. For mobile cranes, the standard EN 13000 sets limits on how large a wind load area (called AW) a load can have relative to its weight – the area must not exceed 1.2 square meters per ton of load. If exceeded, lower wind limits than the crane's normal must be used because the load is actually more exposed than a compact object of the same weight.

§The nameplate determines the limit — not your feelings

Each crane has a maximum wind speed for operation, stated in the manufacturer's manual and often on the crane's nameplate. If this limit is exceeded, work must stop — period. This is not something the operator or signaller judges by how the weather feels; it is a fixed, documented limit, and in many cases work must stop at even lower wind speeds if the load is particularly wind-sensitive.

§Terrain classes and weather forecasts

Wind behaves differently depending on the terrain around you. Terrain is divided into classes from 0 (open water where wind meets least resistance) to 4 (city with many tall buildings where wind is slowed and swirled strongly). Common weather forecasts typically specify wind speeds for terrain class 2 which corresponds to open land with scattered buildings — but a quay facing open water may experience significantly stronger and more unstable wind than stated in the forecast. You must therefore know the difference and not just read a number from an app.

§Other weather affecting work

Wind is far from the only weather factor. Ice and frost make tires, ramps and walkways slippery, fog reduces visibility between machines and people and severe cold or heat wears on both body and equipment over a full shift. Good planning takes the weather into account before work begins — not just when it has already become dangerous.

“A crane that can lift ten tons can still be blown off course by wind — it's not the weight but the area that determines how dangerous the wind is.”