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Fatalities Associated with Improper Hitching to Farm Tractors -- New York, 1991-1995

Approximately half of all injury-related fatalities in the agricultural industry are associated with farm tractors (1). Since April 1991, the New York State Department of Health's Occupational Health Nurses in Agricultural Communities (OHNAC) program * has investigated 27 incidents of sudden rear rollover of farm tractors (i.e., incidents in which the tractor flips backward, rotating around its rear axle (Figure_1); these incidents resulted in 15 fatalities. This report describes four of these incidents, summarizes the characteristics of the 16 incidents that involved improper hitching, and outlines strategies for reducing the risk for their occurrence.

On notification of tractor-associated rear rollovers **, a nurse from an OHNAC regional office and, when possible, an agricultural engineer (supported by the Northeast Center of Agricultural and Occupational Health, Cooperstown, New York) travel to the site of the incident. Both obtain information from witnesses and emergency medical technicians who attended the victim. Case Reports

Case 1. On September 3, 1991, a 71-year-old male part-time farmer was fatally injured when his 1950-model tractor overturned to the rear while pulling a downed tree. He suffered multiple trauma with a fractured neck and jaw. The tow chain used to pull the tree had been hitched above the drawbar *** of the tractor. The tractor was not equipped with a rollover protective structure (ROPS).

Case 2. On December 3, 1991, a 33-year-old male farm worker died as a result of multiple head and torso injuries sustained during a rear rollover of the 1958-model tractor he was using to pull a pickup truck filled with wood. The tow chain had been hitched high on the back of the tractor. The tractor did not have a ROPS.

Case 3. On January 3, 1994, a 42-year-old female farmer died from chest trauma when a 1970-model tractor she was using to pull a loaded pickup truck out of snow overturned to the rear. The tow chain had been attached at the top link connection of the tractor's three-point hitch ****. The tractor did not have a ROPS.

Case 4. On October 29, 1994, a 13-year-old boy sustained fatal massive head trauma when the 1953-model tractor he was using overturned to the rear while pulling a felled 18-inch-diameter tree that was still partially attached at the stump. The tow chain had been hooked directly around the rear axle. The tractor did not have a ROPS. Results of Epidemiologic Investigations

In 16 (59%) of the 27 reported incidents, improper hitching of equipment or material for towing was believed to be the primary cause of the rollover; 10 (63%) of these 16 rollovers resulted in fatalities. The remaining 11 rollovers were associated with various factors, including ensnaring the towed item on a stump, imbalance resulting from pulling an excessively heavy load, or ascending a steep incline in forward gear rather than backing up the hill; five of these incidents resulted in fatalities.

In each of the 16 rear rollovers attributed to improper hitching, attachment of the tow chain to a point above the drawbar was the principal cause of the rollover. Six incidents occurred while the operators were pulling logs, four while removing stumps, and six while pulling vehicles or implements. Only one of these 16 tractors had been equipped with a ROPS; the operator of this tractor had not been wearing a safety belt and had sustained fractures of the clavicle and humerus after being thrown from the tractor.

Of the 16 injured persons, 13 were male. One was aged 13 years; three, 20-40 years; seven, 40-60 years; and five, greater than 70 years. All 10 persons with fatal injuries had sustained massive chest and/or head injuries; in comparison, five (83%) of the six persons with nonfatal injuries had sustained pelvic and/or limb injuries. Of the six persons with nonfatal injuries, two were able to return to work within 2 weeks of injury; both had been protected from crushing, one by a ROPS and one when, by chance, the towed vehicle supported the overturned tractor. One person was able to return to part-time work after 5 months, and three were unable to work 11-15 months after their injuries.

Environmental circumstances that may have contributed to eight incidents included muddy conditions (three incidents); wet ground (two); and snow-covered, hilly, or uneven terrain (one each). Two injuries occurred during January-March, five during April-June, four during July-September, and five during October-December.

Reported by: S Roerig, G Casey, M London, MS, J Boyd, M Hill, M Anderson, A Grant, MS, D Morse, MD, State Epidemiologist, New York State Dept of Health. E Hallman, MS, J Pollock, MPS, Cornell Univ, Ithaca, New York. Div of Surveillance, Hazard Evaluations, and Field Studies, Div of Safety Research, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Rear rollovers of tractors are sudden events: following onset of rotation, the tractor may reach the point of no recovery in a period of 0.75 seconds (Figure_1) (3) -- a duration often shorter than that required by the operator to react and attempt to correct the rearward rotation (4). In this report, more than half (16 {59%}) of the reported rear rollovers involved improper hitching of a load.

A rollover will occur when a tractor's center of gravity shifts beyond the rear stability baseline (the line connecting the rear-tire contact points) (4). For example, when a tractor is used to tow a heavy load, the rear tires may be pressed against the ground with increased force. An excessive load that is correctly attached to a drawbar set at the recommended height will cause slipping of the rear wheels or stalling of the tractor's engine before a rollover is induced (2). However, when a load is hitched high on the tractor or attached directly to the rear axle, less power is required to lift the front end of the tractor than to move the load or slip the wheels, which may result in a rollover through rearward rotation.

Although the association between rear rollovers and improper hitching has been recognized since the 1920s (5), severe injuries continue to occur because of the use of incorrect hitching techniques. The use of ROPS, in conjunction with safety belts, is an engineering strategy that protects tractor operators during rollovers (6). With the exception of use in special situations (e.g., limited vertical clearances), all employee-operated tractors manufactured after October 25, 1976, are required by the Occupational Safety and Health Administration (OSHA) to be equipped with ROPS (7) *****. However, of the approximately 4.5 million tractors used in production agriculture in 1992, only an estimated 1.3 million (29%) were equipped with ROPS (8). For some farm operators, retrofitting a tractor with a ROPS may be a substantial expense (9): in 1993, costs for retrofits ranged from $250 to $2200 (8).

Public health officials and the news media can assist in dissemination of information to tractor operators on strategies to minimize the risk for rear rollover. In addition to installation of a ROPS and use of safety belts, careful selection of the hitching point is critical. For proper hitching to a tractor, the drawbar on a tractor should not be altered by raising or shortening it, and the load should never be attached directly to the axle (2); a two- or three-point hitch should never be used as a single-point hitch instead of the drawbar (10); and loads that attach by a single point should attach only to the drawbar. Other strategies for preventing injuries from rear rollovers include 1) ensuring operator familiarity with the safe use of the equipment; 2) selecting a strong tow chain with a length sufficient to allow adequate stopping distance between the towed object and the towing vehicle to avoid collision and potential rollover; 3) using front-end weights, which counteract lifting of the tractor front end; 4) using a slow, steady pull; 5) maintaining a clear work area to allow sufficient room for maneuvering; and 6) operating the tractor slowly and deliberately. Farm tractors are not designed for logging and other nonfarming activities; therefore, it is particularly important to observe these prevention strategies during such activities. Finally, when a tractor is used to free and tow a stuck vehicle, the operator should hitch the vehicles front-to-front and drive the towing tractor in reverse, which minimizes the risk for rollover by transmitting all the engine power of the towing vehicle through the chain to the other vehicle.

References

  1. Etherton JR, Myers JR, Jensen RC, Russell JC, Braddee RW. Agricultural machine-related deaths. Am J Public Health 1991;81:766-8.

  2. Hathaway LR, Riney LA, eds. Fundamentals of machine operation: agricultural safety. Moline, Illinois: Deere & Company Service Training, 1987:151.

  3. Silletto TA, Hull DO. Safe operation of agricultural equipment. St. Paul, Minnesota: Hobar Publications, 1988:49.

  4. Murphy DJ. Tractor overturn hazards. In: Agricultural and biological engineering fact sheet no. 34. State College, Pennsylvania: Pennsylvania State University, 1992.

  5. Arndt J. Roll-over protective structures for farm and construction tractors: a 50-year review. In: Proceedings of the Earth-Moving Industry Conference. New York, New York: Society of Automotive Engineers, 1971.

  6. Thelin A. Epilogue: agricultural occupational and environmental health policy strategies for the future. Am J Ind Med 1990;18:523-

  7. Office of the Federal Register. Code of federal regulations: occupational safety and health standards. Subpart C: roll-over protective structures (ROPS) for tractors in agricultural operations. Washington, DC: Office of the Federal Register, National Archives and Records Administration, 1994 (29 CFR *** 1928.51).

  8. Wisconsin Rural Health Research Center. A guide to tractor roll bars and other rollover protective structures. Marshfield, Wisconsin: Wisconsin Rural Health Research Center, January 1993. 9.CDC. Farm-tractor-related fatalities -- Kentucky, 1994. MMWR 1995;44:481-4.

  9. US Department of Transportation. Agricultural traffic safety on public roads and farms: a report to the Congress from the US Secretary of Transportation. Washington, DC: US Department of Transportation, January 1971.


* OHNAC, a project supported by CDC's National Institute for Occupational Safety and Health, is based in 10 states and conducts community-based surveillance and intervention efforts to prevent serious farming-related illnesses and injuries.

** In New York, information about incidents was obtained from health-care providers, local extension agents, and the news media. 

*** A drawbar is a solid metal bar that is attached under the tractor frame 14-17 inches above ground and that projects behind the rear wheels for towing. 

**** A three-point hitch is used for attaching and towing farm implements; it is located above the drawbar and consists of two adjustable lower attachment points and a centered upper attachment point. 

***** This OSHA regulation is not actively enforced on farms that employ less than 11 employees, and family farms without other employees are exempt from OSHA regulation; combined, these categories represent most U.S. farms. However, in accordance with a voluntary agreement by tractor manufacturers, virtually all new farm tractors sold after 1985 have come equipped with ROPS.



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