In October 2018, a hoist rope on a tower crane at a construction site broke while lowering a load which then fell to the ground. Although no-one was injured, this was a dangerous incident that could have had very serious consequences. Investigations are continuing.
Preventing a similar incident
This information applies to running ropes on tower and mobile cranes (i.e. hoist and luffing ropes), and primarily to hoist ropes – as the latter are typically exposed to greater wear rates.
The selection of an appropriate rope for a crane is a complex issue due to:
- rope loading, frequency of use (i.e. operational cycles) and rope speed
- rope sheave dimensions including diameters and sheave profiles—a rope sheave needs to match the rope profile as much as practicable. If the sheave is too tight or too loose the rope will be damaged
- the material that the sheave is constructed from can impact on the wear rates of the sheave—a worn rope sheave will accelerate rope wear and damage
- tensile grade of the rope wires—higher tensile strength wires may appear to provide longer life, but in reality this may not always be the case. The individual wires may be less flexible and prematurely fail depending on factors such as the numbers of operational cycles, working loads applied and potential shock loading
- a rope of higher strength wires may have a life significantly less than a rope of lesser strength and greater flexibility
- environmental factors (e.g. is the tower crane being used in a coastal environment)
- rope lubrication and maintenance.
Crane owners are encouraged to only use steel wire ropes of a specification (make, construction, strength) that is both approved and supplied by the tower crane manufacturer for the particular make and model of crane. Where rope of an alternative specification is used:
- written verification from the crane manufacturer that this rope may be used with the tower crane should be obtained
- an inspection of the rope should be carried out by a third party competent person with expertise in the inspection of steel wire rope (National Association of Testing Authorities accreditation of the company carrying out the inspection is one way of helping to demonstrate the quality of this inspection).
It should be noted that internal damage to steel wire ropes can occur without obvious external indicators and is not always readily detectable by visual examination. The competent person may specify non-destructive testing on the rope in addition to a visual examination. The competent person may also prescribe an enhanced inspection program.
While it is acknowledged that the crane operator carries out a basic pre-start examination of the ropes on the crane, additional examination of the rope for internal damage will require the input of people who have greater skill and experience in wire rope inspection.
Since 1 July 2013, there have been 46 notified events involving injuries or the risk of serious injury by falling objects from a crane. One of these was fatal and 24 were serious injuries.
During the same period, we issued 69 improvement notices, 53 prohibition notices and 8 infringement notices for risks of people being hit by falling objects from a crane, with a total of $28,800 in fines.
Each year there are around 15 accepted workers' compensation claims involving a worker being injured by something falling from a crane. Of these claims, around 40 percent involve a serious injury requiring five or more days off work.
Prosecutions and compliance
In 2018, a company was fined $50,000 after a fatal incident involving an 8 tonne mobile yard crane. Although they did not contribute to the fatality, the crane had multiple defects: defective wheel brakes; a defective park brake; broken boom operating wire lifting cables; non-operational headlights, taillights, warning light; and a non-operational horn. Systems were in place for maintenance of plant, but this crane had not received appropriate mechanical repair for a long time.
- Tower crane Code of Practice 2017 (PDF, 1.56 MB)
- Mobile crane Code of Practice 2006 (PDF, 1.34 MB)
- Australian Standard AS 2759 Steel wire rope – Use, operation and maintenance (subscription required)