Cantilevered crane loading platform drop

Issued: 5/9/2025
Last Updated: 5/9/2025

Purpose

This safety alert relates to the collapse of a retractable cantilevered crane loading platform and highlights risk control measures that should be applied to prevent similar incidents.

The information below is relevant to suppliers, installers, builders/principal contractors and users of cantilevered crane loading platforms.

IMPORTANT: These findings are not yet confirmed, and investigations are continuing into the exact cause.

Background

On 29 August 2025, the retractable deck of a cantilevered crane loading platform, loaded with a number of stillages of formwork props, fell from the fourth level to the ground. The cantilevered support frame that was supported on the building slab buckled downwards and outwards so that the retractable deck separated from the guide rails on the support frame (refer to image 1).

The retractable deck rotated as it fell and landed upside down at street level with the stillages of formwork props underneath (refer to image 2).

During the incident, the cantilevered support frame was supported on short legs that raised the support frame approximately 100 mm above the floor slab (also known as stools, refer to image 3).

No persons were injured however, the incident had the potential to cause multiple fatalities.

Contributing factors

The causes of this incident are being investigated. A failure of this type could be caused by a number of contributing factors including the following:

• overload – dead load of materials in addition to impact/dynamic load from crane
• incorrect installation, including excessive cantilever length of the support frame.
  It is important to note where the frame is sitting on the concrete floor slab, the cantilever is measured from the edge of the slab. Where the support frame is supported on short legs (stools) the cantilever is measured from where the support frame sits on the short legs closest to the edge of the slab.
• damaged components
• incorrect or inadequate prop placement and securing.

Image 1: Buckled support frame of failed crane loading platform

Image 2: Retractable deck that fell from the fourth level

Action required

It is extremely important the following is carried out before any cantilevered crane loading platform is used for the first time after installation:

• There is signed certification:
  • from the competent person in charge of the installation, stating the installation complies with the loading bay manufacturer’s instructions, and
  • from a structural engineer verifying loads applied to the building do not overload the building.

• The cantilever length on both sides of the support frame does not exceed the maximum specified by the loading platform manufacturer and is the same length on both cantilever members. It is important to note that cantilevered crane loading platforms are typically designed for use on slabs with straight edges that run perpendicular to the centreline of the loading platform. If the slab edge is curved, steps in, or does not run perpendicular to the centreline of the loading platform, the builder/principal contractor should contact the platform supplier and obtain written confirmation of how to safely install the platform at this location.
• If the support frame is supported by short legs instead of sitting directly on the slab, the cantilever length is to be measured from the short legs and not the slab edge.
• The maximum load applied to the platform does not exceed the manufacturer’s Maximum Rated Capacity (MRC) of the platform, for the cantilevered length being used on site. This should include a specific sign on each platform that specifies the MRC for the cantilever length being used.
• Props, support frames and short legs are installed in accordance with the loading platform manufacturer’s instructions. This includes fixing requirements where specified by the loading platform manufacturer.
• To help prevent overloading of platforms, the builder/principal contractor should ensure documented safe work procedures are developed that enable all workers to safely use the loading platform. This should include training on how to safely use the loading platform and estimates of typical weights of materials being loaded. For example, maximum number of stillages and bins for different trades, assuming rubbish skips being removed from floors are full of heavier material.

All user instructions from the loading platform manufacturer are to be complied with. If the manufacturer states, platform deck must not be rolled when loaded, the user instruction must be followed.

If there is any doubt about the structural adequacy of a cantilevered crane loading platform in use, an independent structural engineer, who is a Registered Professional Engineer of Queensland (RPEQ), should be engaged as a matter of urgency to inspect the installation and verify it is structurally adequate.

If there are concerns the platform has not been installed correctly or is showing signs of degradation, then the platform is to be immediately removed from service and tagged out.

Image 3: Example of a short leg (stool) – this example is 200 mm high, typically they range from 100 mm to 300 mm high.