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Vehicle stabilisers and outriggers

In February 2018, a truck fitted with a vehicle loading crane was driven along a road with its stabiliser extended. The stabiliser struck a parked vehicle and a worker standing behind this vehicle was crushed and killed. It is not yet known why the stabiliser was unsecured and investigations are continuing.

Preventing a similar incident

Stabilisers and outriggers have many configurations depending on the application. They are used to minimise the risk of toppling when the centre of gravity of the combined load and vehicle is outside the support base of the vehicle. Generally outriggers lift the vehicle's wheels off the ground while stabilisers do not. Examples of mobile plant using stabilisers or outriggers include:

  • mobile cranes
  • truck mounted elevating work platforms
  • vehicle loading cranes
  • mobile concrete placement booms
  • mobile amusement rides.

Manually operated stabilisers rely solely on the operator securing the locking mechanism to ensure the stabiliser remains in the travel position. The stabiliser can extend:

  • if the stabiliser is not returned to and effectively locked into the travel position
  • if the stabiliser locking mechanism fails
  • due to incidental forces caused by, for example, the vehicle going over a bump or around a corner.

Hydraulically operated stabilisers are required to be locked in the travel position during road travel.

PCBUs must ensure the components of the stabiliser or outrigger travel position locking mechanism are:

  • in good condition
  • operate correctly
  • free of defects
  • inspected and maintained in accordance with the manufacturer's recommendations and/or guidance provided in relevant technical codes and standards.

The locking mechanism for manually extended VLC stabilisers should include two separate latching devices for each stabiliser and at least one of these should be automatically operated (e.g. a manually operated securing pin and an automatic spring latch).

PCBUs must also ensure workers who drive/operate the vehicles are provided with appropriate instruction, training and supervision regarding the use of the stabiliser or outrigger and their locking mechanisms. The training should relate to the specific make and model of plant and be documented.

Owners of vehicle loading cranes should assess the on-going safety of the current stabiliser locking mechanisms. It may be necessary for an engineer or the manufacturer to redesign, modify or select another locking mechanism that, eliminates or minimises the risk of a stabiliser inadvertently extending while travelling on public roads.

In view of two recent fatal incidents where a truck has been driven without the driver being aware of an extended stabiliser, owners of vehicle loading cranes are strongly encouraged to retrofit units with a warning system to indicate when the stabilisers are not locked in the transport position. The 2014 version of the Australian Standard AS1418.11-2014 Part 11: Vehicle-loading cranes specifies the provision of an indicator to show that the stabilisers are not locked in the transport position. Cranes manufactured to comply with the current standard should include a warning system visible and audible to the driver (i.e. a warning light with a buzzer in the truck cabin.

It is considered to be reasonably practicable to retrofit systems that provide an equivalent level of safety to a crane manufactured after 2014 which includes the warning systems specified by the Australian Standard. The feasibility of fitting an upgraded warning and indicating system to older vehicle loading cranes should be addressed during the annual inspection and maintenance program for the crane.


From 2009-10 to 2016-17 there were 16 accepted workers' compensation claims involving a collision or contact with a stabiliser arm. Most injuries involved people either being crushed/pinched by a stabiliser arm or tripping on a stabiliser arm/pad.

Since 2012 there have been 17 incidents involving the mechanical failure of an outrigger/stabiliser arm (for example: an outrigger/stabiliser arm was being operated without a lock-pin, or an outrigger/stabiliser arm may have sunk in unstable ground, etc.) and five incidents involving a truck mounted stabiliser arms or outrigger swinging loose during transit.

Prosecutions and compliance

In 2016, a company was fined $200,000 after a cyclist was fatally injured after being struck by the stabiliser arm of a prime mover and trailer fitted with a vehicle loading crane. As the vehicle made a right turn, the left-hand stabiliser arm extended and struck the cyclist travelling in the same direction as the vehicle.

Also in 2016, the driver side stabiliser arm of a prime mover and trailer carrying a large amusement ride came loose and struck a car traveling in the opposite direction. The large steel stabiliser extended approximately two metres into the opposite lane. The stabiliser hit the driver pillar and windscreen of the car, killing the driver. The driver was later charged with manslaughter by the Queensland Police Service.

From March 2014 through to January 2015, Workplace Health and Safety Queensland conducted an audit campaign focused on vehicle loading cranes attached with manually extending stabilisers. Forty-two assessments were conducted, and eight improvement notices and one prohibition notice were issued.

More Information

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