SAFETY ANALYSIS OF SURFACE HAULAGE ACCIDENTS Robert F. Randolph, Research Psychologist C. M. K. Boldt, Civil Engineer

U.S. Department of Energy, Pittsburgh and Spokane Research Centers

ABSTRACT industry. As the most common type of machinery involved in surface accidents, Research on improving haulage truck haulage trucks have become the primary target safety, started by the U.S. Bureau of Mines, is for improving safety performance. This paper being continued by its successors. This paper discusses the ongoing efforts by the successors reports the orientation of the renewed research to the U.S. Bureau of Mines (USBM) to efforts, beginning with an update on accident analyze and solve haulage truck safety issues. data analysis, the role of multiple causes in these accidents, and the search for practical Ideally, accidents would not happen. methods for addressing the most important Operating procedures would eliminate all causes. Fatal haulage accidents most often possible hazards, and these procedures would involve loss of control or collisions caused by a always be followed. Equipment would be variety of factors. Lost-time injuries most perfectly designed, flawlessly maintained, and often involve sprains or strains to the back or never operated outside of design parameters. multiple body areas, which can often be The worksite would be constant and attributed to rough roads and the shocks of predictable, introducing no hazards of its own. loading and unloading. Research to reduce Unfortunately, this is an unattainable ideal -- these accidents includes improved warning the realities of people, machinery, and the systems, shock isolation for drivers, worksite are constantly pushing one or encouraging seatbelt usage, and general more of these conditions outside of the ideal. improvements to system and task design. Understanding and controlling the causal factors in haulage accidents is essential to INTRODUCTION reducing their probability of occurring.

Although surface mining has always Accident Causes and Solutions experienced lower accident rates than underground mining, and these rates have been Most accident research now recognizes the generally improving, recent increases, role of multiple causes in accidents, including a particularly in the number of powered haulage significant human performance component. In accidents, have caused concern in the mining the most detailed study of accident causes in mining, Sanders and Shaw (1988) studied Systematic analysis of large numbers of underground mining accidents through an accidents can reveal patterns and expert-panel investigative procedure. Their commonalities that might be not be evident research showed that 88% of accidents had at when looking at a single incident. The analysis least two major causes. This study also showed can be based on industry-wide databases of that “perceptual-cognitive-motor” errors accidents, in-depth analysis of official written (related to the more common term, “human accident reports, or data collected especially for error”) were a causal factor in 93% of the the analysis. Each of these approaches has accidents. While the effort and expense characteristic strengths and weaknesses. entailed in this type of analysis have so far precluded its use in surface mining, the general Industry-wide Databases principles should be applicable. That is, attempting to identify a single cause for every The most widely used source of U.S. accident is usually an oversimplification. Also, mining accident information is the human performance and limitations will often and Health Administration (MSHA) database come into play, even if other factors (poor collected from the quarterly 7000-1 and 7000-2 design, dangerous conditions, etc.) essentially forms. In addition to reports published by the “forced” an error. agency, the raw data is available from their Internet Web site (http://www.msha.gov). This In surface haulage, human performance data is essentially a census of injuries in the becomes a critical issue because of the unusual U.S. mining industry, although it is conceivable demands the vehicles place on their human that some accidents are not reported. The operators: current study reports updated statistics from the MSHA database, bolstered by cost estimates C Roadways and work areas change from the USBM-developed Accident Cost frequently. Indicator model (ACIM) described in more C The sheer mass of the trucks sometimes detail below. requires control inputs (e.g., braking) far in advance of the desired action. Textual Analysis of Official Reports C In large operations, the drive into and out of the pit is long and tedious. In addition to the coded information about C Rough roads and loading impacts can accidents, there is sometimes a written subject the driver to dangerous shocks description available. For instance, accidents and vibration. reported to MSHA on the 7000-1 form also C Visibility is sharply curtailed by the have a brief description provided by the mining bulk of the vehicle. operation. Fatalities have a more detailed Because of these demands, solutions to haulage textual record in the form of an official accident truck safety problems must consider the human investigation report. This textual information, factors aspects of the task, even when because it is free of the constraints of the engineering solutions seem most appropriate. coding system, can incorporate details about the The specific problems that need to be solved accident that might be missed otherwise. The can be determined by studying the accidents fatality reports are particularly informative, involving haulage trucks. containing details about the work procedures, equipment, victims, and even diagrams of the ANALYTICAL APPROACHES accident site. Unfortunately, this approach is not without its limitations. It is very time- Accident data analysis is an indispensable consuming to convert the textual descriptions tool for understanding the causes of accidents. into a form useful for tabulating and comparing All others 6% Dumping shock 15% Rough ground 45% Jarring Other 38% Maintenance 6% 22% All others 21% Loading shock 34%

Equip. operation 46% Ingress-egress All others 26% Collision 36% 9% Passive strain 6% Loss of control 27%

Too close to edge 36% Runaway 27%

Figure 1. Surface haulage truck accident categories in successively higher detail. Based on analysis of written accident descriptions for 1989-91 (Aldinger, Kenney, and Keran, 1995). large numbers of accidents. Key information Too Close to Edge (36.4%) and Runaway can be omitted unless the report writer is (27.3%). Figure 1 shows how these categories following a specified format. This process also and subcategories are related. requires subjective judgements that may be difficult to duplicate or validate. Seatbelt usage is another area where the textual information reveals new accident details. While only 163 of the 2,720 accident This analytical approach was successfully reports studied by Aldinger and Keran (1994) applied to surface equipment accidents by reported whether or not seatbelts were worn, Aldinger and Keran (1994) in an overview of these cases at least suggest some trends. For the entire mining industry, and by Aldinger, instance, none of the fatalities in their study Kenney, and Keran (1995) in a more detailed involved a victim wearing a seatbelt. Also, study of the coal segment of the industry. They injuries tended to be less severe (involving less employed a panel to categorize accidents based time off of work) when seatbelts were worn. on the written narratives in the MSHA database. By using the narratives, they were Special-purpose Data Collection free to develop categories of accidents that were more descriptive than the traditional The most expensive, but potentially most categories. In their study of surface coal rewarding, method of analyzing accident causes mining, Equipment Operation was the most is to perform an independent scientific study. common category of accident for haulage Sanders and Shaw (1988) used this method to trucks (46.3%) followed by Ingress-egress investigate causal factors in underground (25.8%) and Maintenance (22.1%). Within the mining. They conducted independent Equipment Operation accidents, the most investigations of 338 accidents at 20 mines. common types were Jarring (37.7%) and Loss The investigations resulted in detailed of Control (26.8%). The main Jarring descriptions of each accident, including categories were Rough Ground (44.5%), interviews with employees and a study of the Loading Shock (33.5%), and Dumping Shock worksite and equipment. The methodology was (15.5%). Loss of Control categories included based on a systems theory of accidents -- that is, accidents result from a system of interrelated troubling if there were a similar rise in injuries. factors in workplaces, machinery, people, and Fortunately, lost-time haulage truck injuries social structures. declined from 579 in 1994 to 460 in 1995, mirroring an overall surface accident reduction Although this process yielded from 9,040 to 7,883 (figure 2). The overall unprecedented detail about the accidents it trend since 1989 has been a consistent drop in studied, it does have some limitations. The 20 the number of lost time injuries, with the mines studied may not be representative of the exception of a slight rise in 1994. The industry as a whole, especially since the sample increases prior to 1990 can be attributed to consisted mostly of medium-to-large changes and clarifications in reporting underground coal mines. This type of study practices, rather than an actual rise in accidents also tends to be quite expensive, costing (Randolph, 1992; Weaver and Llewellyn, hundreds or thousands of dollars per 1986). investigated accident. Estimated Cost Each of these studies has some merits. The strengths of one approach can be used to The Accident Cost Indicator Model complement the weaknesses of others and add (ACIM) (DiCanio and Nakata, 1976) was used missing pieces to the overall puzzle of true to estimate the total cost of haulage truck accident causes. accidents during 1994, the most recent year for which data are available. The ACIM provides ACCIDENT ANALYSIS cost estimates based on publicly available data on wages, workers’ compensation, medical The accident trends and breakdowns payments, investigation costs, and other direct reported here cover accidents in the MSHA and indirect costs. Although it has some database under the category “Ore haulage limitations, including the omission of data on trucks, off highway and underground.” 90

Accidents classified as occurring underground 80 or to officeworkers were eliminated so that the 70

60 reported data would reflect surface operations Haulage Trucks only. The reported data include independent 50 contractors, and, unless otherwise noted, cover 40 Fatalities All Others the years 1986 through 1995. The 1995 data 30 are currently considered “preliminary” by 20 MSHA. 10 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1986-95 Trends 12,000 Haulage Trucks Surface mining fatalities, including 10,000 haulage truck fatalities, have been generally 8,000 All Others declining since 1986. However, although the industry attained a historic low of 54 fatalities 6,000 in 1994, there was a sharp upswing to 70 4,000 fatalities in the preliminary 1995 data. A injuries Lost-time 2,000 significant component of this upswing was the 0 rise in haulage truck fatalities from 10 to 17. 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 This increase has been a source of concern in Figure 2. Surface fatalities and lost-time injuries, 1986- the mining community. It would be even more 95. independent contractors, it provides a useful by truck drivers. We only know the hours guideline on the magnitude of costs suffered by reported by general work location, not by task, individuals, industry, and society. According job title, equipment operated, or any other more to the ACIM, the six haulage truck fatalities in specific characteristics of exposure. 1994 cost an estimated $2.58 million while the 519 lost-time injuries cost $3.27 million. The Accident Categories total estimated cost for haulage truck fatalities and lost-time injuries in 1994 was more than A more detailed picture of haulage truck $5.8 million. accidents emerges by looking at the MSHA categories into which they fall (figure 5). Independent Contractors Nature of injury. The “nature of injury” The use of independent contractors in the reported for haulage truck fatalities was mining workforce is rising. They account for predominantly “multiple injuries” (64 fatalities) 18% to 67% of the haulage truck fatalities each or “crushing” (34) (Figure 5, top left). The year (figure 3) and from 4% to 13% of the lost- nature of lost-time injuries was somewhat time injuries. The haulage truck accident different (figure 5, top right). Sprains and fatality rate for contractors has been strains were the largest category (2,437 consistently higher than the rate for mine injuries), consistent with Aldinger, Kenney, and operator employees, although their lost-time Keran’s reports of jarring as the main accident rate has been similar (figure 4). Making type. conclusions about these accident rate differences is hampered by a lack of Body part injured. Haulage truck fatalities information about how many hours are worked tend to be catastrophic, involving serious damage to multiple body parts (figure 5, center 25 left). Lost-time injuries (figure 5, center right) Legend Operator 0.035 20 Contractor 24% 0.03

15 18% 0.025 38% Contractors 0.02 Fatalities 10 46% 18% 42% 22% 40% 0.015 20% 5 67% 0.01

0.005 0 Operators 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Fatalities per 200,000 employee-hours 200,000 per Fatalities 0 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 700 Legend Operator 0.4 600 7% 13% Contractor 5% 9% 13% 4% 12% 11% 0.35 500 12% Contractors 13% 0.3 400

0.25 300

0.2 Operators

Lost-time injuries Lost-time 200 Lost-time injuries Lost-time

100 0.15 per 200,000 employee-hours 200,000 per

0 0.1 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995

Figure 3. Contractor and operator haulage truck Figure 4. Contractor and operator haulage truck fatality fatalities and lost-time injuries, 1986-95. and lost-time injury rates, 1986-95. Nature of Injury

Multiple injuries Sprain, strains Crushing Multiple injuries Fracture, chip Contusion, bruise Asphyxia, drowning, etc. Fracture, chip Unclassified, not determined Burn or scald Cut, laceration, puncture Amputation or enucleation Other injury, NEC Concussion Burn or scald (heat) Electric shock Dislocation Heart attack Dust in eyes Other Other/unknown 0 10 20 30 40 50 60 70 0 500 1000150020002500 Fatalities Lost-time Injuries Body Part Injured

Multiple parts Back Head, NEC Multiple parts Body systems Knee Chest Finger(s) Ankle Skull Neck Trunk, multiple Shoulder(s) Brain Hips Head, multiple Chest Neck Trunk, multiple Lower leg Other/unknown 0 10 20 30 40 50 60 70 80 90 0 350 700 1050 1400 Fatalities Lost-time Injuries Activity

Operating haulage truck Operating haulage truck Machine maint./repair Get on or off equip. Walking/running Machine maint./repair Get on or off equip. Handling material Escaping a hazard Escaping a hazard Handling material Hand tools Hand tools Idle Observe operations Inspect equipment Operating utility truck Walking/running Couple/uncouple car Operating LHD Other/unknown Other/unknown 0 10 20 30 40 50 60 70 0 500 1000150020002500 Fatalities Lost-time Injuries

Figure 5. Haulage truck fatality and lost-time injury categories: Nature of injury, body part injured, and victim’s activity, 1986-95. most often involve the back (1,511) or multiple Victim’s activity. The most common parts (959), which is again consistent with the activity recorded for victims of fatal haulage jarring scenario. truck accidents was operating the truck (61) followed by maintenance (12), walking or running (9) and getting on or off the machine (6) (figure 5, bottom left). Operating the truck small surface mining operations -- the median was also the largest lost-time category (2,447 mine size is just four employees. injuries) followed by “get on or off equipment” (1,489), maintenance (547), and handling Figure 6 shows the normalized rates (per supplies or material (331) (figure 5, bottom 200,000 employee-hours) for surface mine right). These categories are roughly consistent fatalities and lost time injuries. The graphs with the findings of Aldinger, Kenney, and show both the overall rates as well as the rates Keran (1995) despite differences in methods for haulage trucks alone. The rates are not and data. clearly higher for the smallest mines. The overall fatality rate for 1-10 employee mines Mine Size (0.0357) was almost the same as that for 51- 100 employee mines (0.0349). For haulage Small mines differ from large mines in trucks only, the rate for 11-20 employee mines important ways, including different geology, (0.0083) was the highest by a very small margin fewer resources, and the special problems over the over-100 employee mines (0.0081). confronted by all small businesses. A common The numbers of fatalities upon which these perception in the mining community is that rates are based were very small, ranging from small mines, at least partially because of the just one haulage truck death for 21-50 factors listed above, are less safe than larger employee mines during 1993-95 to eight operations. Recent analyses of accident rates at fatalities at mines with over 100 employees. different sizes of underground Because lost-time injuries occur in much higher operations (Peters and Fotta, 1994) showed that numbers, they can be more useful than fatalities small mines had a higher fatality rate than large for identifying stable overall trends. mines. However, there was no consistent pattern of higher nonfatal injury rates at smaller mines. Less has been reported about the 0.04 relationship between mine size and safety at .0357 Legend .0349 0.035 Overall Haulage trucks surface mines. .0297 0.03 This analysis differs from the preceding 0.025 0.02 breakdowns of surface truck accidents in .0162 several key ways. Because it examines the 0.015 .0136 characteristics of mining operations as a 0.01 .0083 .0081 .0058 0.005 .0032 possible factor in haulage safety, the analysis .0015 had to be restricted to surface mines only, employee-hours 200,000 per Fatalities 0 1-10 11-20 21-50 51-100 Over 100 excluding the surface operations of Mine Size (number of employees) 5 underground mines as well as preparation Legend Overall 4.12 4.13 plants and mills. It also excludes independent Haulage trucks 4 3.75 contractors because the hours worked by these 3.59 employees are reported by the contract 3 company and cannot be attributed to any 2.55 particular size of mining operation. This 2

analysis used data from just a 3-year period to injuries Lost-time minimize the problems of a constantly 1 per 200,000 employee-hours 200,000 per 0.43 0.46 changing population of mining operations. The 0.24 0.31 0.30 0 accidents were broken down into five mine- 1-10 11-20 21-50 51-100 Over 100 size groupings: 1-10 employees, 11-20, 21-50, Mine Size (number of employees) 51-100, and over 100. There are very many Figure 6. Fatality and lost-time injury rates for different surface mine sizes, 1993-95. The lost-time rates shown in figure 6 Currently the efforts for the Hazard reveal that the highest rates are for the middle- Reduction for Surface Mining project are sized mines. The 11-20 employee and 21-50 aimed at: employee mines have the highest overall rates C Safety Analyses. This will review of 4.12 and 4.13. The peak for haulage truck MSHA accident data to determine root lost-time injuries is also in the mid-range, but causes of recorded accidents. For farther along the mine size continuum at 51- example, slips and falls from powered 100 employees (rate: 0.46). Again, there is no equipment are a major cause of injuries. clear trend toward higher rates as mine size But in evaluating the accident decreases. narratives, nearly half the slips and falls are affiliated with jumping from a CONTINUING RESEARCH vehicle or conveyor. Of those jumping, over half were from vehicles which had In 1995, the USBM laid out new initiatives lost power or brakes. This analysis will for improving surface haulage safety based on a help identify operating practices that history of research (May and Aldinger, 1995). should be modified or avoided to Although the USBM was abolished by improve safety. Congress in 1996, the health and safety C Early Warning. Existing and research functions in Pittsburgh, Pennsylvania developing sensing technology will be and Spokane, Washington were continued. reviewed to determine what systems The surface mining hazard reduction project, might be easily incorporated onto formerly conducted out of the USBM's existing equipment or into current Minneapolis, Minnesota center, is continuing in operations to provide warning to Spokane. The project, "Hazard Reduction for operators and others in the immediate Surface Mining", is continuing to build on past proximity. Currently, engine accomplishments while re-focusing future performance (rpm, oil pressure) and goals to meet the needs of the newly formed machine operating conditions (speed, health and safety research centers. The tilt, load) will be reviewed as possible objective for the project is to reduce accidents parameters that could be used or and injuries associated with coal and recorded to define machine operating metal/nonmetal surface mining. Several safety. In addition, geotechnical strategies are being investigated, including sensing devices, laser surveying, slope improved operating practices, hazard monitoring, proximity warning and recognition, and safety and warning devices. optical sensing devices will be investigated to determine the potential Equipment manufacturers are working to of short- and long-term applications that incorporate alarms, improve vision, and might be used to improve equipment improve ergonomics on large equipment. operating safety. Other approaches involve the development of C Operator Safety. Methods to minimize remote-controlled or autonomous vehicles for injury to operators during accidents will specific extremely hazardous or repetitive, be investigated. Previous research on simple tasks. Improvements in sensing vibration testing done by TCRC will be technology such as GPS, radar, laser, and continued to define and isolate elements infrared offer an opportunity to introduce these that could lessen shock loads to the technological improvements as an aid to operator. Methods to promote seatbelt vehicle operation and/or control. use will also be investigated. C Human Factors. Work will continue to Despite the range of data presented here, be coordinated with the Human Factors there are still many unanswered questions to section at PRC to develop effective pursue: training and ergonomic support designs C How often are seatbelts used, and how for small- to medium-sized coal and can usage be increased? metal/nonmetal surface mining C How many truck drivers are in the operations. In addition, this task will mining workforce, and how many of involve investigations of the them are contractors? Do any of these psychological and physiological factors groups have a disproportionate number of reducing operator-induced accidents. of accidents? C What range of truck sizes are in use. CONCLUSIONS Are some types of accidents more likely for different-sized trucks? There is sufficient evidence from a variety C What haulage safety problems will be of studies, including the data presented here, to solved by automation? What new identify several key problem areas in surface hazards will be created? haulage truck usage. These include: C How can the existing information on C Driver fatalities involving loss of improving haulage safety be vehicle control. These accidents can be communicated more effectively? addressed though a combination of These issues, and others that will emerge from solutions, including haulage roads with more detailed analysis planned during the next less-steep grades, better signs, and year, will guide the development of tools and longer sight lines. Also, driver strategies for improving haulage truck safety. visibility can be improved through mirrors, video cameras, and cab design. REFERENCES Drivers can be educated about keeping their equipment within controllable Aldinger, J.A., and C.M. Keran. 1994 “A limits. Finally, seatbelt usage should be Review of Accidents During Surface Mine promoted for those times when loss of Mobile Equipment Operations” Paper in control cannot be averted. Proceedings of 25th Annual Institute on Mining C Strains and sprains from rough roads, Health, Safety and Research, pp. 99-108. and the shocks of loading or unloading. Road maintenance can smooth out Aldinger, J.A., J.M. Kenney, and C.M. Keran. washboarding and other types of 1995 “Mobile Equipment Accidents in Surface bumps. Loading and unloading Coal Mines” USBM IC 9428, 51 pp. techniques, such as lining the truck bed with small material before loading large DiCanio, D. G., and A. H. Nakata. 1976 boulders, can reduce shocks. Also, “Accident Cost Indicator Model to Estimate suspensions can be used to dampen the Costs to Industry and Society From transmitted shocks. Work-Related Injuries and Deaths in C Strains and sprains resulting from a Underground Coal Mining, Volume I. slip or fall while mounting or Development and Application of Cost Model” dismounting the truck. Improved (contract JO255031, FMC Corp.). BuMines railings, non-skid surfaces, and damage- OFR 39(1)-77, NTIS PB 264 438. 202 pp. resistant ladders are some of the ways of helping drivers to mount and May, J.P., and J.A. Aldinger. 1995 “Overview dismount their vehicles safely. of Bureau Research Directed Towards Surface Powered Haulage Safety” Paper in Proceedings of 26th Annual Institute on Mining Health, Safety and Research, pp. 121-131.

Peters, R.H., and B. Fotta. 1994 "Statistical Profile of Accidents at Small Underground Coal Mines" Paper in Improving Safety and Small Underground Mines, Proceedings: Bureau of Mines Technology Transfer Seminar, Compiled by R. H. Peters. USBM SP 18-94, pp. 5-14.

Randolph, R.F. 1992 “Human Factors of High Technology Mining” Paper in Proceedings of the Symposium on New Technology in Mine Health and Safety at the Annual Meeting of the Society of Mining, Metallurgy, and Exploration, Inc., Phoenix, AZ, pp. 287-295.

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Weaver, R. J., and R.G. Llewellyn, 1986 “Report on 30 CFR Part 50" MSHA PC-7014, 49 pp.