ACTION AREA: MAINTAINING SAFETY WARNING SYSTEMS
INTRODUCTION: In the summer of 2002, researchers from Auburn University's Industrial and Systems Engineering Department conducted a study to document and assess the condition of warnings associated with forest harvesting equipment used in the Southeastern United States. Thirty logging operations within approximately 100 miles of Auburn, Alabama were visited. The types of forest harvesting equipment observed included grapple skidders, feller-bunchers, knuckle-boom loaders, forwarders, whole tree chippers, and one processor.
Fig. 1: Warning has experienced severe, permanent degradation.
Fig. 2: Warning with severe temporary degradation.
Fig. 3: Temporarily degraded warning, following minor cleaning.
The study defined "warning system" to include all modes of communicating safety information to the equipment operators, maintenance personnel, and owners. The two primary mechanisms for conveying safety information associated with this class of heavy equipment are (a) on-product warnings and (b) the operation/safety manuals. Subjective criteria (translated into a five-point scale) were developed to rate the intensity of degradation experienced by each on-product warning. Further, the availability of operation/safety manuals, a requirement of OSHA logging regulations (29 CFR 1910.266), was determined for each machine.
FINDINGS: A total of 1,581 on-product warnings were photographed in the field. Three judges independently evaluated each label with respect to degradation that was both temporary (i.e., dirty, obscured labels) and permanent (i.e., physical damage such as scratched and worn labels). Previous research using these degradation scales has determined that degradation above level two has negative impact on legibility and the subsequent understanding of a warning. Considering temporary degradation alone, only 12.4 of the warnings experienced sufficient degradation to impact comprehension. Similarly, when considering physical damage alone, 36.8 of the warnings were rated in the two lowest levels of degradation intensity. Based on this research, over a quarter of the warnings (25.1 ) are unlikely to be understood.
The overwhelming majority (95.2 ) of warnings with elevated levels of degradation were on the exterior of the equipment. Further, machines that operate away from the thick underbrush and heavily wooded areas, such as loaders, are not subjected to as harsh an environment and consequently had a significantly lower percentage (3.5 ) of severely degraded warnings. Wear/abrasion (55.9 ) and scratches/tears (30.7 ) were the most frequent modes of physical damage. Statistical analysis of the data found that the (a) type of equipment, (b) model year, (c) placement of the warning, and (d) type of damage are related to increased levels of degradation, sufficient to impact comprehension of the intended safety messages.
During the inspections, only 49 (43.7 ) machines had the operation/safety manuals available. In fact, there were only four (13.4 ) sites visited which had manuals for all of the equipment being operated. A machine with a model year of 1996 or earlier was 2.7 times more likely to have the operation/safety manual missing (Odds Ratio = 2.65, 95 CI = 2.3 to 3.1). Further, 27 (24.1 ) of the machines had at least one warning with deterioration so severe it would likely prevent communication, as well as having no manual available. In these cases, all precautionary information transmitted through the warning system (with respect to the hazard addressed by the degraded label) had, in effect, been eliminated.
DISCUSSION: Taken as a whole, the current status of warning systems in forest harvesting equipment is adequate, considering the exceptionally harsh environment in which this equipment is used. However, increased maintenance and replacement of warnings is necessary to restore these warning systems. Owners and operators of this equipment are not adequately maintaining the warning systems. In order to promote proper maintenance (i.e., inspection, cleaning and replacement of degraded or missing warning system components), presentations at industry groups and continuing education courses are being planned.
A warning that is illegible or obscured will have little value to experienced equipment users, beyond a potential reminder, and even less for new or inexperienced users. Based on these results, it is reasonable to suggest that on-product warnings should be more frequently inspected and replaced (when appropriate) for (1) machines routinely operated in thick underbrush and heavily wooded areas (i.e., feller-bunchers and skidders), (2) machines that are more than six years old, and (3) labels located on the attachment or the exterior body of the machines.
Additional research is planned on the development and use of more durable warning sign/label materials. This research was supported by a grant from the United States Forest Service under USDA Forest Service Agreement No. SRS-02-CA-11330132-087.
Jerry Davis, Ph.D.
Department of Industrial & Systems Engineering
Auburn University, Alabama 36849-5346
Southcentral Technical Division
Please follow equipment manufacturers' recommendations for safe operation and maintenance procedures.