A fatality occurred on 20 June 2019 when a 110 tonne haul truck crossed a windrow and fell down a pit wall. At this stage of the investigation, the following is evident: the loaded truck entered a single lane section of roadway with two narrow points. When it reached the second narrow point, the truck's right side wheels rode up and over the windrow. As it straddled the windrow, its forward movement was initially arrested with the right side wheels over the crest edge, but the truck then slid over the edge falling 15 metres to the lower bench.
Direct causes
The truck was exiting the pit when it failed to negotiate a narrowing section of roadway on the ramp. The right wheels rode up over the crest edge windrow leading to the truck straddling the windrow before it teetered and fell over the edge.
Contributory causes
- A 'step in' on the crest side reduced the bench width by over 20% along a 25 metre section.
- The 'step in' was on the driver's offside which has restricted visibility.
- The crest (drop-off) edge windrows were located along the immediate edge of the bench.
- The size and shape of the windrow, as well as adjacent material buildup, assisted the truck's wheels to ride up over the windrow.
- There was no demarcation or signage in the near area.
- The truck did not change the angle of approach to avoid the 'step in'.
- The incident occurred between dawn and sunrise when the light is changing, affecting visibility.