In July 2018, an operator and a surveyor were in a mobile elevating work platform (EWP), taking survey measurements on a stacker structure to improve conveyor belt alignment. They were working in close proximity to the underside of the stacker conveyor frame, located about 27 metres above the ground.
When the operator moved the EWP basket upward, his head became trapped between the stacker frame and the secondary guarding sensor bar in the basket. The alarm at the EWP base alerted the spotter, who then proceeded to lower the basket. The operator received injuries that had the potential to be serious, and he lost consciousness for a few minutes.
Direct causes
The operator was leaning over the controls when he moved the EWP basket upwards, trapping him against the conveyor structure above.
Contributory causes
- The job hazard analysis (JHA) did not identify the hazard of being crushed against the stacker.
- The EWP basket was directly below and in close proximity to the stacker conveyor frame.
- The EWP operator activated the boom extend function instead of boom retract.
- The EWP function speed control was set in fast mode (rabbit) instead of slow mode (tortoise).
- Although activation of the secondary guarding sensor bar prevented further movement of the EWP basket, it did not retract the basket due to insufficient continuous pressure being applied.
- There was a delay in bringing the basket to the ground, as the spotter was unaware of the boom operating envelope programmed into the EWP safety system.