Exposure to Whole Body Vibration in Mining, Transportation, and Construction Principal investigator(s): Alan W. Salmoni (University of Western Ontario) Co-investigator(s): Joel Andersen (Occupational Health Clinics for Ontario Workers); Tammy Eger (Mining and Aggregates Safety and Health Association); Ted Gardiner (Battle Mountrain Canada); Yves Lajoie, André Plamondon, Lloyd Reed (Laurentian University); Nancy Lightfoot (Northeastern Ontario Cancer Research Centre); Kamlesh Prajapati (Boart Longyear) Sponsoring Institution: University of Western Ontario For more information on this study, please contact Alan W. Salmoni: asalmoni@uwo.ca Overview While there has been a huge amount of research concerning the amount and the effects of vibration transmitted through the hands of an equipment operator, this is not the case for vibration transmitted through the body of a seated vehicle operator (e.g. a truck driver is exposed to vibration transmitted through the seat). This latter vibration is called whole-body-vibration (WBV) and has been linked to such health risks as low back pain and spinal degeneration. There is a recognized need for further research in this area. The current research project studied exposure to whole-body-vibration in the mining, transportation, and construction industries. Operator Exposure to Whole-Body-Vibration in Mining Operator Exposure to Whole-Body-Vibration in Long-Haul Trucks Operator Exposure to WBV in Construction Operator Exposure to Whole-Body-Vibration in Mining Results The dominant axis for vibration transmission was normally the z axis (vertical). Crusher plants, dozers, and scissor lifts were the exceptions (x or y axis). LHD vehicles, dozers, and graders were found to exceed 4-hour exposure guidelines. Muck machines and cavo loaders (both tested with the operator standing) exceeded the 1-hour exposure guidelines. For locomotives and jumbo drills, operators were tested in seated and standing positions because both postures are used during operation. For both pieces of equipment exposure was higher while standing. Importantly, however, neither piece of equipment or posture exceeded 8-hour limits. For locomotives and jumbo drills, the equipment was tested while operators were standing on the platform with and without anti-fatigue matting. The vibration was somewhat attenuated by the matting (4-10 per cent). Conclusions It is important to note that for all pieces of equipment tested very small samples were used. The degree to which these conditions are representative is unknown. In addition, we could find no studies with which to compare our results for most of these pieces of equipment (most of this equipment is specialized to the hard-rock mining industry). Further research is clearly warranted before firm conclusions and recommendations can be made (the recommendations made below are tentative in nature). The findings reported above for dozers and graders do not appear to represent significant health hazards since miners typically operate these pieces of equipment for short periods of time per day (<4 hours per day). In contrast, LHDs are typically used by the same operator during extended periods of time and appear to represent a significant health hazard. These results agree with a past study by Village et al. (1989). Therefore a more comprehensive study of LHDs seems warranted. More research is clearly needed for equipment on which operators stand. In the submitted article on standing exposure we question the logic of using whole-body-vibration guidelines, which have been developed for seated operators. The vibration transmission characteristics of a standing posture are almost certainly different than that of a sitting posture. In addition to knowing little about the physics of the differences between whole-body-vibration exposure when standing versus sitting, nothing is known about the potential differences in health risks to the operator. While the amount of vibration exposure was highest for cavo loaders and muck machines (compared to the other mining equipment tested), very few miners in Ontario operate this specialized equipment and their daily use is normally limited in duration. While our results support the use of anti-vibration mats, a large-scale study testing different mats under different work conditions seems warranted. Objective Compared to transportation, very little research has been conducted on whole-body-vibration in mining. Because of the lack of scientific information a descriptive approach was used where many types of equipment were evaluated. This information would then be used to propose further research on selected pieces of equipment, identified as particularly problematic. Methods Eleven different types of mining equipment including: scissor trucks, jumbo drills, LHD vehicles, underground haulage trucks, crushing plants, 150 ton trucks, surface graders, dozers, muck machines, locomotives, and cavo loaders were tested for whole-body-vibration exposure. All were evaluated at two Ontario mining sites during typical operation. Operation of most equipment exposed workers to whole-body-vibration via the buttock-seat interface, except for crushing plants, cavo loaders, and muck machines. These latter pieces of equipment caused us to question the ISO standards for whole-body-vibration, as standing appears to be a different exposure mechanism than sitting, yet the safety guidelines do not differentiate. Vibration exposure was assessed using a triaxial accelerometer (seat pad) following the 1997 ISO 2361-1 guidelines. In the case of the standing measurements the operator stood on the pad rather than sitting on it. Vibration was assessed using 120 samples randomly selected during operation. These samples were eventually averaged together before comparing the data to the safety guidelines (ISO and ACGIH). Back to Top Operator Exposure to Whole-Body-Vibration in Long-Haul Trucks Results As a general finding, most trucks were quite safe (i.e., vibration exposure to the operator fell within the acceptable range of the 1997 ISO guidelines. Transport operators who were typically exposed to ten hours of driving did not exceed the limits suggested. However, the overall summed RMS acceleration does place them within both the health and comfort caution zone. The major contributor to vibration exposure differences was road condition, with rough road conditions producing higher levels of vibration than smooth conditions. The dominant axis through which vibration acted was the z axis. Neither rough nor smooth conditions exceeded the 8 or 16-hour exposure limits suggested by the ACGIH TLV guidelines. A second difference, although small, was truck type. Super trucks exposed operators to higher levels of vibration than conventional trucks. Seat type, driver experience, and truck age did not produce differences in vibration exposure. Conclusions Even though truck age did not produce differences in vibration exposure, this result must be qualified within the context of the present study. All trucks tested were less than three years old, as the participating transport company replaces its trucks on a regular basis. Trucks older than those tested may produce greater vibration exposure. Winter/spring driving conditions were not tested. In Northern Ontario at least, road conditions deteriorate significantly during these months. Further study of these conditions is warranted before conclusions can be drawn about (Northern Ontario) yearly exposure limits. Government is currently debating on whether to allow truckers to spend more time per week driving. As it relates to exposure to vibration and the types of trucks tested in this study, it would appear that this would not represent a significantly increased health risk. Road condition was the major predictor of amount of vibration exposure and this leads to two implications. First, it is important for highways to be maintained properly if exposure levels are to be minimized. For long-haul trucks the rough stretches of highway produced a significant amount of vibration and jolting. However, because these sporadic conditions were averaged over a lengthy trip, they had a minimal effect on total exposure. Second, even though short-haul trucks were not tested, it would be predicted that short-haul operators could easily be exposed to severe amounts of whole-body-vibration if the route they travelled repeatedly was on a poorly maintained road. Our results also indicated these potentially dangerous roads could be effectively identified by the operators themselves. The drivers in the present study were very capable of identifying rough road conditions. It would be very easy to compile road condition data using drivers as the source for information. A number of uses could be made of this type of data that would be valuable for good operator health and safe driving. Objectives To determine the WBV characteristics of trucks used for long-haul transportation purposes, by describing exposure to WBV using factors described by the industry and the research literature as contributory to different levels of vibration. To determine the WBV characteristics frequently experienced in hard rock mining and in construction, by describing exposure to WBV in workplaces and under operating conditions identified by the industry as significant. To share the results with mining, construction, and transportation stakeholders so that exposure to WBV can be eliminated or reduced, by presenting at conferences/workshops and to companies and workers, and by publishing the results and recommendations in academic journals and safety association publications Methods A total of 68 trucks (all from one trucking company) were tested as they travelled on one of four major Provincial highways (Hwy 144, 17W, 17E, 69S). Trips began in Sudbury and ended in Timmins, Sault Ste. Marie, Ottawa, and Toronto. Whole-body-vibration exposure was measured following 1997 ISO 2631-1 standards. Using a triaxial accelerometer, vibration was measured in the x axis (forward direction of truck), y axis (sideways direction of truck), and z axis (vertical). Vibration data was collected continuously for five-minute segments randomly selected during every 30 minutes of travel time. The variables studied to investigate whether they were predictive of the quantity of vibration exposure included: operator experience (<2 years, >2 years), road conditions (rough, smooth), truck age/mileage (<150,000 km, >150,000 km), seat type (National, Bostrum), truck type (conventional, super truck). Variables such as truck maintenance, driving speed, and amount of load were controlled. After analyzing the data according to 1997 ISO 2361-1 guidelines, analyses were computed to see which variables could account for vibration differences. In addition, overall vector summed RMS values were compared to ISO 2631 guidelines and peak frequency-weighted RMS accelerations and frequency spectra were compared to the American Conference of Governmental and Industrial Hygienists (ACGIH, 2000) threshold limit values. Back to Top Operator Exposure to WBV in Construction Results Mobile equipment produced significantly more exposure to whole-body-vibration than did stationary equipment, however, there was no differences between tire and tracked equipment. When the weighted RMS accelerations were compared to the 1997 ISO 2631-1 standards for health caution zone, 7 of the 14 pieces of equipment exceeded the limits. The seven were tracked and rubber tire loaders, off road dump trucks, scrapers, skid-steer vehicles, backhoes, and bulldozers. When comparing the vehicles to the ISO standards for comfort caution zone, operators of all the equipment tested, except mobile crane operators, would experience some degree of discomfort. Scraper operators were exposed to very uncomfortable whole-body-vibration levels. The rest of the equipment was rated as uncomfortable. Conclusions It is important to note that for most pieces of equipment tested very small samples were used. The degree to which these conditions are representative is unknown. However, the mean RMS values found in the present research fall within the ranges reported in two other studies in the literature. This adds credibility to the findings and recommendations below. Many pieces of equipment exceeded the 8-hour limit values set out in the ISO safety standards. The operators may be uncomfortable during operation and have a greater risk of injury/negative health outcomes. A comprehensive study of these pieces of equipment is clearly warranted. As was the case for mining, these pieces of equipment are very expensive and have a fairly slow turnover rate. This suggests that one necessary strategy, if decreasing whole-body-vibration exposure is a goal, would be to retrofit the equipment with reasonably-priced elements. Since the vibration is primarily transmitted through the buttock-seat interface, the best solution may be to redesign and then change the seats. It would seem advisable to limit the total continuous or intermittent exposure times for operators of equipment exceeding the ISO standards (see findings). When questionable, it is relatively easy to test specific equipment on a piece-by-piece basis. Operators should avoid rough sections whenever possible and travel at speeds appropriate for conditions. Construction companies should purchase equipment with the best vibration dampening systems and insure that these are maintained properly. Objective Compared to transportation, very little research has been conducted on whole-body-vibration in construction, even though there are many types of equipment for which vibration is a potential health risk. Because of the lack of scientific information a descriptive approach was used where many types of equipment were evaluated across several construction sites in the Greater Toronto Area. Methods Whole-body-vibration exposure of construction equipment including bulldozers, excavators, scrapers, graders, skid-steer vehicles, backhoes, compactors, tracked loaders, concrete trowel vehicles, zoom booms, mobile cranes, rubber tire loaders, off road dump trucks, and forklifts was measured. A wide variety of construction sites were used including residential, corporate, and public sites. In all, 67 pieces of equipment representing 14 different types were tested. Testing sessions for each piece of equipment consisted of continuous 20-minute samples (insuring that at least one complete work cycle was tested for each type of equipment). Vibration exposure was assessed using a triaxial accelerometer (seat pad) following the 1997 ISO 2361-1 guidelines. Samples from the same types of equipment were eventually averaged together before comparing the data to the safety guidelines (ISO). Publications Cann, A.P., Salmoni, A.W., Vi, P., & Eger, T. (2003), "An exploratory study of whole-body-vibration exposure and dose while operating heavy equipment in the construction industry." Applied Occupational & Environmental Hygiene 18:999-1005. Cann, Adam P., Salmoni, Alan W., Vi, Peter, and Eger, Tammy R. (2004), "Predictors of whole-body vibration exposure experienced by highways transport truck operators." Ergonomics 47(13):1432-1453. Disclaimer Back to Top