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The Case of the Fatal Forklift
Myron J. Boyajian, President, Engineering Consultants -- Design News, January 4, 2009
Inspection and analysis of an accident usually provides a cause. An attorney may cease the investigation early, leaving conclusions drawn from meager evidence. While these conclusions may allow litigants to financially close the case, the forensic engineer is left with a void — a vague sense that there was more to the case.
At a kitchen accessory manufacturer's warehouse, production raced to load the dealers' shelves ahead of the coming holidays. Forklift operators hustled to move products from the production floor to storage and then to the shipping docks. Each electric rider forklift was equipped with a multi-stage, high lift mast and large, square-shaped, padded clamps. Light, but bulky, loads included step stools, tray table sets and kitchen accessories. The large, low-weight boxes lent themselves to being high-stacked in multiples of two and four boxes at one time.
The Scene of the Crime
Production continued until one driver failed to return her forklift to the battery charging station at the end of the night shift. The warehouse supervisor stopped all loading operations and sent day shift forklift operators to look for the missing operator and forklift. She was found pinned between her forklift and an H-section, roof support beam.
First responders removed the injured operator to a trauma center. A tracheotomy and other emergency measures failed to save her as she remained unconscious and then expired.
The forklift was sequestered while investigations commenced. The operator's mother, her only family, filed a wrongful death suit against the forklift manufacturer and a maintenance company, citing negligent design and improper maintenance, respectively.
The Investigation
I was retained by the plaintiff's attorney to reconstruct the accident. Service records indicated the 3-year-old truck received regular maintenance. Examination of the forklift showed correct drive control operation and the four-stage mast lifted smoothly to its 200-inch lift height. The big, paddle-like carton clamps operated smoothly. There was a hand-operated parking brake that cut off power to the forklift motor. The truck was found with its load elevated, the hand brake released and the direction control switch in the forward position. A seat switch to detect the presence of the operator that cut off power when the operator left the seat was in place, but was bypassed.
I then reviewed the work environment and the driver's performance. Records showed she had been a safe, careful driver with no criticism of unsafe driving. Her loading orders showed she was to have placed several boxes atop a group of other high-stacked boxes. There was a narrow gap between the H-beam roof column and a tall stack of other boxes. It appeared she intended to go into that space to lift and place the load.
Since she was trapped by the right front corner against the column, I considered the possibilities that a sloped floor permitted the truck to roll, that a fellow employee drove the forklift and struck the deceased operator as she spotted the load placement or that the operator herself improperly operated the truck while off the truck seat.
The Smoking Gun
The floor was billiard table flat and level and no one came forward to admit operating the forklift. With little else to go on, I theorized the driver caused the accident. Because of reduced visibility due to the high lift and large carton clamps, the driver got off the truck to spot a load set-down point. With the hand brake released and a bypassed seat switch, she then used her hand to operate the accelerator pedal to ease the truck forward.
Focusing on the load, she drove the truck forward, crushing herself against the column. I alerted the attorney as to my hypothesis of improper operation, while noting the faulty switch as an issue of poor maintenance. I was asked to cease all further work. The case dragged along for several years until the attorney called to say the case settled. He did not reveal the terms of settlement, tersely saying only that “it was enough.” The case concluded, but the mystery remained.
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So.... Where is the rest of the story for the deadly forklift mystery?
Paul Evans - 2009-13-4 00:58:27 EDT
