A quarry operator was travelling back to the crusher fully loaded in a CAT 775G. The haul route had become slippery shortly after a down pour of rain. As the dumper approached one of the main ramps from the top of the quarry The operator engaged the correct gear with auto retarder. As the dumper descended the ramp at a speed of approximately 9mph it began to lose traction. The operator had no control over the steering causing the dumper to hit the bund on the opposite side of the ramp. The sideways impact of the bund caused the dumper to roll over onto the cab side and prevented a more serious incident. Luckily, the operator was shaken but thankfully unharmed.
KEY FINDINGS
Driver Training
- The employee has been with the company just over a year and has previous experience in mobile plant operation
Maintenance and inspections
- Daily pre-use checks were carried out with no defects found.
- Service and maintenance regime was in place and up-to date.
- An external report was carried out on the vehicle with no report of defects related to the incident
Conditions and behaviour
- The Operator was travelling at 9.3mph, below the sites speed limit.
- The operator was not using a mobile phone.
- The operator was wearing a harness belt.
- After a particularly long dry spell an unexpected heavy downpour of rain caused the ramp to become slippery.
- Certain parts of the ramp had become steeper in gradient due to years of scraping.
- A shovel was in the process of road maintenance on the ramp.
- Bund heights were maintained correctly which prevented the Dumper from rolling over the edge.
Warning Signs
- The ramp had been slightly slippery when wet with the water bowser for dust suppression. A decision was made to only supress the dust on one side of the ramp (The Incline).
Follow up
- Post incident alcohol test was completed & the test was negative.
- Ramp has now been built back up between 1 in 10 & 1 in 12.