Wind speed

Crane manuals state limits in metres per second. The forecast on your phone is in kilometres an hour. This is the bridge between the two.

What each speed feels like

The descriptions are the standard Beaufort scale wording — the same language weather services have used for a century. They are there to sanity-check a reading, not to replace one.

Three things worth getting right

• Your crane’s limits are in its manual, and nowhere else. Every machine and every configuration is different, and a crane in service, being erected, or parked out of service has three different figures. This page will never tell you what a limit is — only what a number converts to.
• A manual’s figure means the wind at the crane. Not the forecast for the city, and usually not the reading at ground level either. Wind climbs with height. Read the anemometer on the machine and check what the manual is asking for — a mean speed or a gust.
• The load matters as much as the speed. A big flat panel catches wind that a coil of rebar never notices. Wind limits assume a load with an ordinary sail area; something with a face on it comes down sooner.

We have written up how the wind rules work in British Columbia in plain English: tower crane wind limits — working, erecting, out of service.

Crane manuals state their limits in metres per second. Your phone forecasts in kilometres an hour. This page converts — it will never tell you what a limit is.