Mineral Mines & Quarries Inspectorate | Alert | No.436 V 1 | 20 October 2023

Rollover of large excavator while ascending ramp

What happened?

On 11 September 2023, an operator in a large excavator in North West Queensland was ascending a ramp to a bench in preparations to load trucks. One of the tracks departed from the ramp and the machine became unstable. While attempting to correct the position of the machine on the ramp the excavator rolled onto its side.

The operator was able to extricate himself from the machine and was transported to hospital for assessment and treatment.

How did it happen?

The investigation identified a number of contributing factors, including:

• One track of the machine departed from the ramp during the ascent.
• The machine was not in the correct configuration to ascend the ramp (drive motor position).
• There was limited visibility due to the time of day (before sunrise), no in-pit lighting and the operator's position in the cab.
• The ramp used to access the bench was narrower than the site specification and was not compacted.
• In-pit inspections did not identify the ramp as being outside site specification.
• There was a lack of clarity amongst supervisors regarding the ramp specification and procedures.

Key issues

• Checking the quality of constructed bench access ramps against site and Original Equipment Manufacturer's (OEM) requirements.
• Machines must be in the correct configuration to ascend and descend access ramps.
• Visibility for in-pit operations pre-dawn.
• Rollover protection structures for mobile equipment can help mitigate the consequences of a rollover event.

Recommendations

All site senior executives should:

• Ensure access ramps are:
  • built to specification based on OEM requirements, good industry practice and a risk management process
  • periodically inspected by competent workers to ensure they comply to specifications
  • not used if they don't comply to specification
  • designed with adequate lighting for night and pre-dawn operations, taking into account the visibility from the operator's position in machines.
• Ensure all workers who may be able to assist in an emergency are trained in the access and emergency egress systems for the mobile equipment working in the pit.
• Ensure seatbelts and operator restraints are in use to reduce the severity of injuries in rollover events.

References and further information

The Queensland Mines Inspectorate has previously published information regarding rollover of mobile equipment, including contributing factors and recommendations to industry to prevent the rollover of excavators. The contributing factors have been relevant to recent incidents in the industry, and the recommendations remain valid.

Mines safety  bulletin no. 109, 18 Aprill 2011 - Preventing  Excavators from rolling over

Further information has been published by the Coal Inspectorate regarding multiple rollovers of dozers.

Coal Inspectorate Bulletin  no.213, 15 August 2023 - Dozer rollovers