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SECTION III: MATERIAL HANDLING ACCIDENTS
Summary No. 11 - Unbalanced Dump Truck Load
Employees were exposed to the hazard of being crushed by a dump truck trailer bed that contained an unbalanced load.
A dump truck is used to load scrap bauxite into barges.
Activity at time of incident:
A flagman was guiding a semi-trailer dump truck driver during the transfer of wet scrap bauxite from the truck into a barge.
Longshoremen are transferring scrap bauxite (which has the consistency of wet, sticky clay) from a terminal storage area to a barge using a dump truck and a pan rigged to a crane. A bucket loader operator fills each dump truck with scrap bauxite at the terminal storage area. The dump truck driver then transports the load to the wharf, where a flagman directs the dump truck driver as he backs up to the edge of the wharf and aligns the truck with the barge. The driver raises the hydraulic bed to allow the bauxite to slide out the rear of the bed into a pan which is used to guide the material into the barge. The flagman stands between the crane and the driver's side of the dump truck to communicate with the truck driver.
At the time of the incident, the flagman directed a tri-axle tractor-trailer dump truck into position at the edge of the wharf adjacent to the barge. Standing near the end of the trailer on the driver's side of the truck, the flagman then directed the dump truck driver to begin raising the hydraulic trailer bed. The trailer bed was raised about halfway when it began to sway from side to side and then tilted to the driver's side. The driver stopped raising the bed, and was about to warn the flagman, but the bed continued to tilt. The the flagman saw the truck bed turning over and attempted to run out between the crane and the dump truck, but the trailer bed flipped onto its side and fell on him. Had the victim remained where he was, or gone under the truck, he would not have been struck.
The scrap bauxite had adhered to the top of the raised truck bed, rather than sliding out the bottom, causing the bed to become unbalanced as it was raised higher. The bauxite had also adhered to the bucket of the loader, and the bucket loader operator bounced the bucket over the trailer bed to break the bauxite loose while loading it into the dump truck.
The dump truck was found to be in good condition. The solid concrete wharf was level and in good condition.
Just prior to the incident, when the bed was raised about one-quarter of the way, the truck bed began to sway from side to side. However, this was a fairly common occurrence and therefore did not concern the driver.
In the week prior to the incident, the flagman had assisted in unloading more than 600 loads. Three different types of dump trucks were used in the operation, including a tri-axle dump truck, a dual- axle dump truck, and the tri-axle tractor-trailer truck involved in the incident. The trucks capacities were 82,500, 88,000, and 92,500 pounds, respectively.
Applicable Standards and Control Measures
The crushing hazard presented by the tipping dump truck could have been prevented by ensuring that the flagman was in a safe location away from the dump site. This hazard may also have been prevented by ensuring that the dump truck was evenly loaded with the scrap bauxite before the truck proceeded to the wharf for unloading.
Other Relevant Standards and/or Control Measures
1. 29 CFR 1917.27(a)(1): Personnel - Qualifications of machinery operators. "Only those employees determined by the employer to be competent by reason of training or experience, and who understand the signs, notices, and operating instructions and are familiar with the signal code in use shall be permitted to operate a crane, winch or other power-operated cargo handling apparatus, or any power operated vehicle, or give signals to the operator of any hoisting apparatus."
All employees involved in the operation, including the dump truck driver, the bucket loader operator, and the flagman, must be trained in hazard recognition and safe work practices, and are competent in the signaling instructions used during the operation in accordance with the above standard.
Page last updated: 04/13/2010