 What is ergonomics? Ergonomics, or as it is sometimes called human factors, makes sure that the work environment is designed to fit human capabilities. It relates human characteristics, abilities, expectations, and behavior to the design of machines, tools, facilities, environments, and procedures. Using ergonomics has been shown to be an effective way to reduce accidents and injuries in the workplace. The Bureau of Mines Pittsburgh Research Center has a group which focuses on ergonomics research. The group consists of about 25 engineers, psychologists, sociologists, and training specialists. A study currently being performed by the Bureau is using ergonomics to determine what problems, if any, are associated with deep-cut mining, or cuts greater than 20 feet, so that corrective actions can be recommended. Tools such as interviews, accident analysis, and task analysis are being used by Bureau researchers in this study. The goal of this project is to improve safety in deep-cut mining sections by providing the mining industry and equipment designers with practical tools and work methods based on human factors or ergonomic principles. Recommendations from this project could be realized in terms of equipment changes, procedure changes, and or training materials. This research was begun for several reasons. Data from another Bureau study found that taking deep cuts may play a role in why miners sometimes go under unsupported roof, for example, when continuous miners break down well into a cut. Also, the United Mine Workers, AMSHA, and several state and local agencies wanted more information about the special safety considerations when taking deep cuts. The objective of this project is, first, to identify existing problems, if any, in deep-cut sections. Secondly, it is anticipated that recommendations for changing the design of equipment, work procedures, and training will be made, and these changes will be evaluated. Third, contacts will be made with designers of equipment used on deep-cut sections so that ergonomics can be incorporated into the design process. The first step of the project is to identify potential problems associated with deep cuts. This will be done by examining AMSHA reportable accidents for potential problem areas and by observing and interviewing miners who work on deep-cut sections. Results from this initial information gathering are then used to develop task analysis procedures. The task analysis will be used to examine potential problem areas more closely. Once any potential problems have been identified, potential solutions, such as equipment redesign or work method changes, can be developed. These changes are then evaluated to make sure that they are practical and effective. This information will then be given to the mining industry through seminars and publications. Some of the most objective measures of mine safety are the frequency and severity rates of mining accidents. An important part of the research to look at the safety of deep-cut mining has been an evaluation of mine accident data collected by AMSHA. In particular, accident data of mines that had AMSHA approval to take deep cuts has been compared to accident data of mines which did not have approval to take deep cuts. The analysis focused on small mines, those less than 50 employees. Furthermore, the analysis didn't include mines with long-wall sections, since these sections are so different from continuous mining sections and may bias the results or wash out any differences. The analysis only included injuries which resulted in lost time or were fatal in 1990 and 1991. There are some limitations with the analysis. First, we don't know if a deep cut was being taken at the time of the accident, only if the mine had approval to take deep cuts. We assume that deep-cut mining is more prevalent at mines with deep-cut approval. Also, the existence of long-wall systems and mine size influence accident rates and we have looked at these factors in our analysis. There are other factors though which also influence safety. These include mining conditions, seam height, geology, the type of ventilation system used, the makeup of the workforce and the management structure. So these results are only generalizations and cannot be used to make inferences about specific mines. However, these results may provide insight as to the nature of accidents in deep-cut mines so follow-up studies can be performed. The first step in the analysis was to see how accident statistics vary according to mine size and according to whether the mine had approval to take deep cuts. Then small mines were examined to see what kind of accidents were occurring in deep-cut and non-deep-cut mines. Specifically looked at were the type of accident, the workers' activity and the job titles of those injured. These results do not provide us with complete information but do provide us with areas to further look into with other techniques such as interviewing the workforce and using task analysis. On the average, deep-cut mines tend to be larger than other mines. In fact, mines with deep-cut approval report more than three times the number of employee hours per mine than mines without deep-cut approval. This fact highlights the need to normalize the number of accidents to exposure hours. Any analysis that doesn't may be misleading. The overall fatality rate of mines with deep-cut approval was about half that of mines without approval. It was 0.05 versus 0.1. These rates were similar within each size category though. This implies that mine size is a more important factor than deep-cut approval status and its effect on fatality rates. Mines with deep-cut approval report a slightly higher accident rate than those without approval, 14.17 versus 12.47. It appears that mine size played a significant role in this difference as well. Larger mines reported lost time injuries at a higher rate than small mines. Now let us look at the type of accidents found in small mines broken down by deep-cut approval status. In small mines, handling materials was the largest single category of accidents accounting for more than 30% of all accidents. Deep-cut mines had an almost 20% higher rate of reported material handling accidents than did non-deep-cut mines. One possible explanation for this statistic is that as deeper cuts are taken, the trailing length of continuous mining machine cable is longer. So the length of cable to be handled is longer. The longer cable is more difficult to move and is more likely to result in an injury. This figure also supports this explanation by showing that moving cable is associated with a 26% higher incidence rate in deep-cut mines. The accident rate due to handling supplies also is higher in deep-cut mines by about 22%. Slip and fall accidents have a substantially higher rate in deep-cut mines by about 82%, but these accidents only account for about 7% of all accidents in small mines. These are all areas for further investigation through task analysis. According to the data presented in this slide, the job titles of shuttle car operator and continuous miner operator have higher accident rates in deep-cut mines by 20% and 63% respectively. These jobs are prime candidates for further investigation through task analysis so that the reasons for these increased rates can be determined and safety measures developed. A questionnaire was used to determine what aspects of deep-cut mining are considered the most critical to the mining industry. So far, over 75 mine workers, including mine operators and supervisors, have been questioned at various mines with deep-cut approvals throughout Pennsylvania, Kentucky, Maryland and Ohio. The questionnaire addresses various aspects of the workers' experience, mine conditions and the mine workers' view of safety of deep-cuts. Our goal is to cover as many areas as possible to identify any problems particular to deep-cut mining. In general, the results of the interviews were positive. 74% of the workers in large mines, those mines with greater than 100 employees and 95% of the workers in small mines, those mines with less than 100 employees, said deep-cut mining improved or maintained their productivity levels. The miners believe that deep-cut mining is safer because they move the equipment less, thus decreasing the probability of moving accidents. They commented that they were more mobile and therefore able to get out of the way of the miner quickly and more safely than when on the deck of the miner. They also felt they were exposed to less noise and dust. Several concerns with deep-cuts were raised. 67% of the operators interviewed said there were visibility problems and 29% said that it was at least sometimes difficult to stay on-site line in deep-cuts. Several of these continuous miner operators stated that a 40-foot cut is the maximum safe cut because visibility problems begin to occur after that point. Also, the operator's position when operating the miner has become an important safety concern in deep-cuts, as voiced by many of the interviewees. The boulder's workload has been described as the heaviest of all job position. The boulder operators are concerned that the miner operator will have to wait on them to finish bolting the section. One-third of the roof boulder operators in the study of a six mines with deep-cut approval said that they found themselves hurrying to stay ahead of the continuous miner every day, and another 24% said that this happens to them a few times a week. This workload may encourage the boulder to take shortcuts either to keep up with the miner or to take a break. The type of shortcuts mentioned were spacing bolts further apart than the roof plan allows, or neglecting to do methane tracks or drill test holes, and to check the torques on the bolts. Another important concern is the length of time between bolting. Some believe that the longer the top sits unboldened, the greater the probability of the roof sagging and possibly falling. 57% of the continuous miner operators interviewed were concerned that the roof falls and deep cuts were both deeper and have larger surface area than roof falls and standard cuts. 37% of the roof bolters interviewed thought that ground falls may be larger in deep cuts. It has been found that deep-cut roof falls average three times larger in area and 1.5 times greater in thickness than non-deep cut roof falls. The Bureau has taken a systematic look at safety issues in deep-cut mining through the use of the questionnaire, the statistical analysis, and past operator positioning analysis. One such experiment on operator analysis was completed at the Bureau in 1991. It studied operator positioning at several mines which were taking deep-cut approvals. The study recorded the positioning of the miner operator backing through cross cuts, first cuts, second cuts, and moving at the face. Each observation, occurring approximately one per minute, included the operator's position and his direction of view in relationship to the miner, the ventilation curtain, and the last row of bolts. The location of other workers and their equipment was noted along with the activity being performed. These observations were made in comparison to what the standard operating procedures depicted as the safe location for the operator in that mining activity. For example, during the first cut the operator should be positioned in this safety zone. However, this is where the operator was observed. So 22% of the time the operators were observed in an unsafe position according to the standard operating procedures. This comparison shows the difference between the standard operating procedure and what the operator really does. The difference can be attributed either to that the standard operating procedure is impractical or the operator is being unsafe. When interviewed, the operator said they had to position themselves there for visibility reasons. This may mean that we should take a closer look at developing practical, reasonable, and more importantly, usable standard operating procedures. The results of these interviews, past studies, and statistical analysis are being used to determine what areas need further examination. The Bureau plans to perform task analysis to break down the problem and develop possible solutions. The areas of interest immediately involve miner operator positioning while cutting coal and also when tramming from place to place. We're interested in what they need to see, where they need to be to see it, and the training of these tasks. We want to see what hazards may exist due to their positioning such as pinch points, inability to see other workers, and the proximity to unsupported top. Roof folding is also an issue. Recent fatalities have caused us to look more closely to the equipment design, the work procedures, and the workload. Is it as safe to bolt a deep cut as it is a standard 20-foot cut? Is the workload more taxing? How can the process be made more safe? We are working closely with other groups at the Pittsburgh Research Center to get a global look at the deep cut process. Other areas where some have expressed concern are ventilation plans, methane liberation and methane checks, dust exposure, and the general area of remote control. We're interested in any concerns you may have on this issue. Our plan for the next one to two years is to study several mines before deep cut approval is granted, and then go back to the study after they have acquired their deep cut approval. In this way we can help to diminish the differences between mines when performing the studies. We are currently interested in the continuous miner and the roof boulder positions. Recent continuous miner operator fatalities have directed us to pay particular attention to cross cuts, breakthroughs, and trimming the miner from place to place. Roof boulder fatalities are driving us to research the mental and physical stressors associated with roof bolting as a result of the equipment and procedures followed. We expect to work closely with other projects such as the retreat mining, prevention of ground fall accidents, and small mines and independent contractors since there is substantial overlap into these other projects. The outcome of this research will help us to identify and address safety concerns associated with deep cut mining objectively. This can lead to improved equipment design and job redesign recommendations. One outcome the Bureau plans to develop from this research is a method for mine management to use when implementing new mining technology, whether it is equipment or methods. This will provide them with a tool for evaluating the human factors aspects of technological changes and to better plan and design for these changes. We can help them determine their training needs and ultimately reduce accidents and costs. If you are interested in obtaining more information or would like a copy of the publication, the name of the paper is an ergonomic and statistical assessment of safety and deep cut mining and is published as a special publication SP18-94 Improving Safety at Small Underground Mines. The publication is available through NTIS 5285 Port Royal Road Springfield Virginia 22161 or call 1-800-553-NTIS to obtain a copy of the publication.