Safety alert issued after worker struck by excavator bucket
In November 2022 a worker was seriously injured when he was struck by an excavator bucket at a construction site. Initial enquiries found that the excavator was operating near the worker when its bucket unexpectedly detached from a quick hitch on the dipper arm, striking the worker. Operating powered mobile plant at a construction site exposes workers to a range of health and safety risks, including the plant overturning, things falling on the operator, the operator being ejected from the plant, and the plant colliding or coming into contact with workers, other vehicles or plant, energised powerlines or other things. Workers are also at risk of mechanical failures such as hydraulic failures and the release of hazardous substances.
A quick hitch (also known as a quick coupler) is a latching device that enables attachments to be rapidly connected or disconnected from plant. Quick hitches are commonly fitted to earthmoving plant and there are different types available. While these devices save time and effort compared to changing attachments that are directly coupled to the plant, people have been killed in Australia when attachments have fallen off the quick hitch due to loss of hydraulic pressure. Other factors that contribute to these kinds of incidents include workers being in the vicinity of operating plant, and operators having restricted visibility of ground workers or nearby pedestrians, particularly those close to the plant around blind spots.
Taking steps to manage risks is a condition of doing business in Queensland. Persons conducting a business or undertaking (PCBUs) are advised to use a hierarchy of controls to help decide how to eliminate and reduce workplace risks. The hierarchy of controls ranks types of control methods from the highest level of protection and reliability to the lowest. PCBUs must work through the hierarchy of controls when managing risks, with the aim of eliminating the hazard, which is the most effective control.
There are significant risks associated with using mobile plant fitted with quick hitches. Before operating any piece of mobile plant, PCBUs must ensure that a suitable combination of operator protective devices for the plant is provided, maintained and used so far as is reasonably practicable, and that the plant (or part of the plant) does not collide with pedestrians or other powered mobile plant. When there is risk of collision, PCBUs must ensure that the plant has a warning device to warn other persons of the risk. Some common risk control measures can include specific controls that should be considered for excavators fitted with quick hitches.
PCBUs should provide excavators that are fitted with fully automatic quick hitches that don’t require the operator to insert a safety pin to prevent the quick hitch releasing. They should also ensure that where fully automatic quick hitches are not provided, safety pins are always used, and that all quick hitch attachments have the original manufacturer’s safety system.
A safe system of work should be implemented to manage the risks associated with mobile plant and associated attachments. This could include ensuring that the plant and attachments are selected, used, inspected, maintained and repaired according to the manufacturer’s recommendations and specifications. This includes ensuring the attachment pin centres and pin diameters are within the dimensions and wear tolerances specified for the particular quick hitch. Using attachments with incorrect pin diameters and centres may cause the safety system of a quick hitch to be ineffective. PCBUs should also ensure the manufacturer’s instructions are included in a safe work procedure on how inspection and maintenance should be carried out.
Plant operators must conduct daily pre-start checks on the general condition and maintenance of the plant, including the quick hitch assembly. PCBUs should also ensure that the safety system only allows attachments to be disconnected from the quick hitch by intentional means, so unintentional disengagement is prevented. They must also ensure that the operator has received adequate training and instruction in the use of the plant. In some circumstances, the mobile plant operator may also need to hold the right risk work licence.
Plant operators and ground workers should be made familiar with the blind spots of the plant being used. A safe system of work should also consider the following safety measures regarding mobile plant and blind spots. Induction training programs should be developed to emphasise the dangers of people working near mobile plant. PCBUs must ensure that all relevant information, training, instruction and supervision is provided before work begins.
PCBUs are also advised to consider operational exclusion zones, taking into account the type of work being performed and the particular movement of the plant. Where possible, PCBUs should minimise the need for workers to be inside exclusion zones while the plant is operating, and use physical barriers that prevent workers or plant access to designated areas, such as fencing, para-webbing or water filled barriers.
Before work starts, PCBUs should develop an effective system of communication (such as two-way radios and hand signals), based on two-way communication between mobile plant operators and ground workers. Before allowing workers to enter a hazardous zone (such as the slew radius of an excavator), the dipper arm should be lowered and the machine turned off or the controls disengaged to prevent inadvertent activation of the controls. Any remaining risks must be minimised with suitable personal protective equipment (PPE), such as hard hats, steel cap boots, eye protection, hearing protection and high visibility vests.
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