On a clear, calm, spring morning in the Appalachians, a tractor-trailer dump rig, commonly called a coal bucket, was in the process of dumping a load of ground-up wood fuel at a mill’s woodyard. A smaller, straight dump truck backed in beside the coal bucket and also prepared to unload.
The coal bucket truck driver/owner was close to 60 years of age and had been driving agricultural commodity trucks all his adult life. The driver of the straight dump truck was in his mid-60s and hauled wood fuel for a tree service company. He was also an experienced driver. Both drivers were wearing hardhats and safety glasses.
UNSAFE ACTS AND CONDITION:
The coal bucket rig consisted of a tractor and an attached dump trailer with hydraulic self-raising capability. This dump can be raised extremely high in the air and can become unstable when used to dump loads (such as ground wood) that may not slide off the truck easily without raising the dump to the full height. The straight dump truck operator did not use good judgment in parking his truck so close to the coal bucket.
At full extension, the (still fully loaded) coal bucket became unstable from the high center of gravity. It began to fall over to the right side. The straight truck operator, who had walked to the rear of his truck to open his tailgate, noticed the shadow of the falling truck and quickly retreated. The coal bucket driver was out of the truck cab and was not able to stop his truck and trailer from tipping over completely.
The straight dump truck driver fell down and scraped his hand during his retreat. The driver of the coal bucket was not injured.
RECOMMENDATIONS FOR CORRECTION:
• Recognize that ground-up wood fuel and bark does not flow out of trailers the way gravel, coal, grain, and other loose materials do; it tends to hang together and come out of the truck all at once, magnifying any miscalculation in dumping a load with a hydraulic-lift trailer, with weight extended into the air.
• The woodyard decided to prohibit coal buckets, or any other combination truck with attached dumptype trailer and hydraulic hoist self-unloader, from self-unloading wood fuel. (Dump trucks consisting of one unit attached to the truck’s frame, walking floor trailers, and tractors with box-type trailers do not present this same hazard.)
• It is dangerous to permit more than one self-unloading rig to unload fuel in the same area unless rigs are widely separated and the drivers are aware of each other’s presence.
• With self-unloading tractor-trailers, examine the immediate proximity for levelness and stability before backing the rig to the dumping spot on the woodyard.
• Drivers of self-unloading dump rigs that require the operator to stay in the cab must wear seatbelts during the dumping process.
• Woodyard front-end loader or dozer operators should periodically check the residue pile and keep the ground regularly graded, level, and solid to maintain a safe dumping area.
Southwide Safety Committee;
Appalachian/Southwide Region Manager