Safety alert issued after elevated work box falls from integrated tool carrier

The NSW Resources Regulator recently issued a safety alert following an incident in which a workbox detached and fell two metres from an integrated tool carrier.

The work box hit the ground and rolled 90 degrees onto its side, and two mine workers located in the work box, were partially ejected from the work box and suffered minor injuries.

The incident, which occurred on 9 January 2021, occurred when two workers were tasked with installing a secondary vent fan from the roof in the main decline of an underground metalliferous mine using an integrated tool carrier and combination fan lifting/work box.

The work box, with fan restrained, had been attached to the integrated tool carrier during the previous shift and parked in a nearby adjacent heading ready for the commencement of work. In line with the requirements of a prestart inspection, the operator believed he had confirmed engagement of the attachment locking pins by lifting the work box from the ground and tilting it forward. He did not visually inspect the locking pins to ensure they had fully engaged the work box attachment.

The hydraulic isolation valve was placed in the isolated position and all three workers placed personal isolation locks to stop any inadvertent operation of the locking pins during operation.

The fan was raised and secured to the roof before the work box was partially lowered. During this lowering, the work box detached from the integrated tool carrier and fell to the ground. Upon hitting the ground, the work box rolled 90 degrees onto its side, ejecting the two workers.

An inspector from the NSW Resources Regulator attended the site on the day of the incident and conducted an assessment which identified the following contributing factors:

• The attachment locking pins appear to have been only partially extended and had not fully engaged the work box’s attachment to the coupler of the IT.
• A visual inspection of the locking pins to confirm the full engagement of the attachment was not undertaken.
• Workers relied on the IT operator to have properly assessed the effectiveness of the locking pin control measure prior to placing their locks on the hydraulic isolation valve.

The alert recommended mine operators review their safety management systems, particularly focusing on ensuring that:

• Control measures employed to ensure the effective and secure coupling of work boxes and implements to mobile machinery are reviewed, taking into account the hierarchy of risk controls.
• Operational switches in mobile equipment are of an appropriate type, positioned and labelled appropriately to prevent inadvertent operation and consideration is made to install additional barriers or protection of the locking pin release switch.
• Each worker verifies the effectiveness of a control measure prior to placing their isolation lock and tag.
• Information, instruction and training are provided to, and implemented by workers for the safe use of workboxes.