Strong winds will impose additional loads on a crane and may affect the crane’s stability. According to the Tower Crane Code of Practice 2017, a maximum permissible operational wind speed of 54km/hour (15 metres/second) has been traditionally specified for tower crane operations in Queensland, and applies when a crane operator is at the controls, and in the process of lifting a load.
A number of tower cranes (including Falcon Cranes fleet of Tower Cranes) are now being designed for a maximum operational wind speed of 72km/hour (20 metres/second) as specified in AS 1418.4: Cranes, hoists and winches – Tower cranes.
However, although the tower crane base and crane ties may have been designed for this higher operational wind speed, there are many other factors to consider and ultimately crane operators should not operate the crane in wind speeds they consider to be unsafe.
The effect of wind gusts will also have a different effect on the crane than a constant wind. A crane operator must base the decision to make a lift on information provided by the crane manufacturer, and prior experience as a crane operator. If the operator believes a specific crane operation is hazardous, the operator may choose not to operate the crane.
According to the COP, where a non-standard lift with a suspended load or large surface area is to be undertaken in windy conditions, a “competent person” should provide written advice on safe lifting conditions (e.g. when lifting panels consult panel manufacturers to determine permissible wind speeds).
How Falcon Cranes Mitigates The Risks:
Falcon Cranes supply a Tower Crane Manual at each job site which includes manufacturers specifications on permissible wind speeds according to the surface of a load lifted. It is important that you locate the manual for the crane you are working with and familiarise yourself with this document (see attached example).
In addition to this, Falcon Cranes also supplies all tower cranes with Anemometers to show accurate wind speed readings, and flags to assist with visually identifying wind directions.
Finally as per our Tower Crane Operations SWMS / Rigging & Dogging SWMS, taglines must be used whenever lifting loads in windy conditions, to assist with maintaining control over the load.
Operating In High Winds:
If a tower crane must be operated in wind speeds greater than 54km/hour, a documented risk assessment must be carried out to determine:
- the types of loads that can be lifted under these conditions
- the control measures that need to be applied. The risk assessment should involve a consultative process between the principal contractor, crane owner and operator, and other members of the crane crew. Matters to be considered during this consultative process include:
- load surface area size to weight ratio (density) (e.g. a timber wall form will be more easily affected by the wind than a concrete panel of the same frontal area)
- boom length and surface area of the boom, including any attachments
- the ability of the crane’s slew motors and brakes to operate safely in high winds
- the ability of doggers to control load movement, particularly when it is being slung or unloaded
- the ability of the crane operator to see the load, particularly when the load is being slung or unloaded
- the effect of wind on crane movement (e.g. slewing against wind or luffing down against wind), which may present a risk of rope bunching on the drum and the boom dropping on rope luffing tower cranes.
- Only tower cranes that have been designed to operate in wind speeds greater than 54km/hour may be operated under these conditions.
You can view the original post written by Ryan Graham from Work Safety QLD posted on Falcon Cranes website here