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3 Understanding Self-Escape C hapter 2 provided the context for understanding self-escape in terms of the regulations and safety practices of underground coal mining in the United States. In this chapter, the committee turns to the specific task of self-escape in a mine emergency. One thing that has become clear over the course of this study is that neither the formal statement of task for the committeeâs work nor the time allowed was sufficient to permit the committee to detail the full extent of the complexities of self-escape. Thus, although this chapter discusses self-escape in some detail, it is in- tended as an overview of the task. Our framework for understanding self-escape is provided by concepts central to human-systems integration (see Chapter 1). Human-systems in- tegration studies the relationships among people, tasks, and the tools and equipment needed for them and the environment and broader system within which they must operate. These relationships are examined to optimize safety and performance and to determine better ways to train people: they are particularly important to examine for complex environments that are high stress and potentially life-threatening. We begin the chapter with discussion of the context of past mine emergencies in which self-escape took place. Next we discuss analyzing the task of self-escape to determine the demands placed on miners and offer a first order look at breaking down the steps of the self-escape task. We then turn to the people and technologies currently involved with self-escape. We conclude with our recommendations. 37
38 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES CONTEXT OF MINE EMERGENCIES This section reflects a wide range of input to the committee, including information presented to the committee by a range of stakeholders in mine operations, a review of investigation reports from recent mine emergencies (which included transcripts from interviews with miners who escaped), the available research, as well as the knowledge gained during committee site visits to an underground coal mine and a mine training facility. Since the 2006 MINER Act, a number of safety improvements have been made to emergency preparedness in underground coal mines. Mines have increased their supply of self-contained self-rescuers (SCSRs) with units available to individual miners and caches placed at fixed distances within escapeways. Mine operators have been instructed to train under- ground coal miners quarterly on the use of SCSRs. Mines have installed lifelines in their primary and secondary escapeways and provided tethers to link miners together in emergencies (National Mining Association, 2009). Improved communications and tracking systems, many with hand-held wireless radios, have been deployed. (The resources available to assist min- ers during emergencies are discussed in greater detail later in the chapter.) However, because many of the available reports and investigations, as well as the research, reflect experiences in mine emergencies prior to 2006, this summary does not necessarily reflect all the improvements and current conditions. It has become clear to the committee that the conditions surround- ing past major mine emergencies and subsequent escapes were complex. Moreover, we found few commonalities except that there was a problem that necessitated escape and that efforts were made to follow protocol and training to make decisions during the escape. Even in the same type of incident, such as a fire or an explosion, the underlying causes and subse- quent failings have varied such that minersâ considerations and reactions are different. The number and type of personnel underground at the time of mine emergencies is also variable. This section illustrates this complexity. We examine the events precipitating emergency incidents, initial responses, the mine environment and what can change in it during an emergency, the physical and psychological demands on miners, and the role of other miners and personnel for support. Precipitating Events Across history, most disasters (defined as an incident with five or more fatalities) have been classified as caused by explosions (82 percent of di- sasters, 92 percent of fatalities) (see Table 3-1). Those caused by fire are a distant second by number of events (7 percent) as well as fatalities (6
UNDERSTANDING SELF-ESCAPE 39 TABLE 3-1â Underground Coal Mine Disasters, 1900 to 2011 Type Number of Events Number of Fatalities Explosion 421 10,419 Fire 35 727 Haulage 21 145 Ground Fall/Bump 14 92 Inundation 7 62 Other 17 199 NOTE: The Mine Safety and Health Administration defines a disaster as an incident with five or more fatalities and classifies disasters by cause and number of fatalities. Disasters due to haulage result from failures in the transportation of personnel, material, or equipment. Disas- ters due to ground fall or bump indicate the fall of roof rock or outward bursting of walls in an underground work area. SOURCE: Brnich and Kowalski-Trakofler (2010, Table 1). percent), followed by ground fall and then inundation. In the past decade, the events causing and signaling dangerous conditions have varied across all the emergencies, including those with no fatalities. Explosions, explosions in sealed areas, fires triggered by belt slippages, rock falls, lightning strikes, water inundation, and roof/rock falls have all necessitated the evacuation of miners from underground coal mines (U.S. Department of Labor, 2002, 2003a, 2003b, 2007a, 2007b, 2007c, 2011; West Virginia Office of Min- ersâ Health, Safety, and Training, 2006; United Mine Workers of America, 2011, n.d.). In some cases, conditions in the mine have exacerbated the situation and increased the danger to miners, such as accumulated coal dust or other combustible materials, poor ventilation, ventilation controls damaged by explosion, missing or damaged firefighting equipment, or the release of toxic gases. Warning signals have been highly variable and have included carbon monoxide (CO) alarms, the smell of smoke or visible smoke, belt stoppages and subsequent investigations of why belts stopped running, visible fires, heat, blasts of air, dust or debris, breathing difficulty, inundations of water, rock falls, and unusual noise. Initial Response In some emergencies, warning signals were normalized or dismissed by the miners until they received a notice to evacuate or conditions worsened. As discussed in Chapter 4, this kind of minimizing reaction is common hu- man behavior. However, time is lost, making the efficiency of escape more critical once the necessity of evacuation is determined. In a study of the first moments of response to an underground emer-
40 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES gency, researchers for the National Institute for Occupational Safety and Health (NIOSH) interviewed miners who had survived mine emergencies to gather information on what happens at the beginning of an emergency (Kowalski-Trakofler et al., 2010). Those survivors often credit the outcome to having a good response plan in place and having been adequately trained on the plan. In the first few minutes of the emergencies, miners have sought to gather information and first aim to understand the nature of the emer- gency, which people are affected, and whether a second event can happen. They often look toward a leader and note that successful leaders appear confident and calm and are able and willing to make decisions. When faced with a fire or other alarm or notified to evacuate, miners have responded as they were trainedâto report to a designated area and assemble as a group. Then they coordinated the evacuation. For nearby fires, miners who have been designated (and trained) for firefighting often stayed behind to try to extinguish the fires. The miners determined whether the mantrip1 could be used for exit. When it was not, traveling by foot was necessary and a smoke-free path if available was the first choice. When communication was available, the status, location, and plans for evacuation were reported to the surface or nearby sections, usually by the foreman. Groups of miners stayed together and in poor visibility grabbed onto one another. In conditions of dense smoke, heavy dust, or elevated gas levels, miners stopped to don their SCSRs. Investigations of emergencies have revealed that the donning of SCSRs was not always an initial response and was at times put off longer than the conditions warranted (U.S. Department of Labor, 2007a, 2007b; Kravitz and Gibson, n.d.). Mine Environment During an Emergency A great deal of variability exists across underground coal mines on many dimensions: geologic features of the seam (dip, undulations, seam thickness variations, etc.), mining method (primarily longwall or room and pillar), equipment selection (continuous haulage, belt, rail, etc.), egress points, and property boundaries. In addition, roof heights vary from very low (low seams are 42 inches or lower) to very high (14 feet). The number of possible exits is also highly variable, with mine configuration and size as well as constraints to provide required communications and ventilation. Every mine is required to have designated at least two separate and dis- tinct escapeways that meet the requirements laid out in the code of federal regulations (see Appendix A). However, lengths of these escapeways will vary from mine to mine. In some mines, there may be long distances to the 1â A mantrip is a train-like vehicle that transports miners to and from locations within the mine.
UNDERSTANDING SELF-ESCAPE 41 mine exit. In recent escapes, miners have traveled the primary escapeway, track entry, intake air course, or belt entry to exit the mine. In one emer- gency, miners had to travel approximately 3 miles to reach an exit (U.S. Department of Labor, 2007b). In some mine emergencies, resources that are usually available were not. In several incidents, the mantrip could not be used or later became unavailable because of heavy smoke or debris on the track, and the miners had to travel out of the mines on foot. Similarly, in fires in which the fire or heat destroyed equipment, communication was lost or incomplete (e.g., in the Fairfax Mine fire underground miners could hear the surface but the surface could not hear them). Other equipment, such as fire suppression systems and ventilation controls, was also damaged in some incidents. Heavy smoke or dust (or both) made the atmosphere less breathable and decreased visibility in several events and was present in some paths or sections though not others. In poor visibility, miners reported using the coal rib2 or other miners to guide themselves out. The atmosphere also can be toxic: in some incidents, miners died of CO poisoning or others were found with significant amounts of CO in their blood. Physical and Psychological Demands Known and unexpected conditions (e.g., heat, limited visibility, low ceilings, obstacles, effects of CO) and escape requirements (e.g., wearing SCSRs, walking long distances and inclines) have taxed minersâ physical and psychological abilities. Miners of varied ages from their 20s to their 60s, and likely varying abilities, have been involved in past emergencies. Emergencies put everyone in nonroutine roles where they have to make de- cisions in relatively unfamiliar and stressful circumstances. In recent events, added stresses have included loss of communication either through equip- ment damage or use of the SCSRs, smoke and loss of visibility, unmarked doors and paths, and missing crew members. Miners have reported feeling scared; some have reported paralyzing fear when faced with concerns about physical capabilities, families, and imminent dangers (Kowalski-Trakofler et al., 2010). Recent investigations have uncovered the difficulties miners encounter when donning SCSRs. Difficulties have included problems taking the SCSRs out of the carrying pouches and finding the lanyards to activate the units, perceptions that the units are not working, feelings of nausea, and loss of the unitsâ safety goggles (U.S. Department of Labor, 2007b). In addition, despite warnings and obvious hazards, miners have not put the units on if they felt they could breathe well enough on their own or believed the 2â he T coal rib, or wall, is the solid coal on the side of any underground passage.
42 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES ability to communicate or yell was more important (West Virginia Office of Minersâ Health, Safety, and Training, 2006; U.S. Department of Labor, 2007a, n.d.-b). In some cases, after donning the SCSRs, individual miners took the units off to communicate to or yell for other miners (U.S. Depart- ment of Labor, 2007b). Some members of the committee had the opportunity to experience simulated conditions of a mine emergency in a training mine. A quarter-mile walk in heavy theatrical smoke and wearing SCSRs took us 25 minutes. Although some experiences were anticipatedâinability to see in the smoke, inability to talk when wearing SCSRs, discomfort with SCSRs, and heat and other limiting conditionsâwe concluded that these difficulties are not fully appreciated or understood until experienced. We found that being among the group, holding the lifeline, and having visual experiences (reflections from headlamps on the smoke or reflectors on the minersâ vest or in the mine) created some comforts during the drill. But losing sight of oneâs fel- low miners for short periods, as well as the slow movement, heat, sweating, and dry mouth created mild anxiety. Other Miners and Personnel The committee was told often that miners stick together as a group to the extent possible. They are a highly cohesive population with a special bond. We know from the research that leaders emerge in emergency situa- tions and that these people are not necessarily the day-to-day leaders. These leaders who emerge have been recognized as aware and knowledgeable, open to input from others, decisive yet flexible, having a calming influence and the ability to gain followersâ confidence, and logical decision makers (Kowalski-Trakofler et al., 1994). For the most part, the people involved in emergency events have been able to account for miners who are underground and have demonstrated working knowledge of their locations at the start of the events, as well as potential paths for egress. This has broken down when communications were lost and conditions in the mine became unknown. For example, in the 2002 Fairfax Mine fire, with communications down, a group of miners who went back into the mine to look for a section crew did not cross paths with the exiting group. The section crew exited well before the searching miners gave up and exited the mine (U.S. Department of Labor, 2003b). Although most underground mining personnel are directed to evacuate in an emergency, some miners have roles to try to mitigate the situation or have done so in the process of evacuating. They have fought fires, and some of these fires were extinguished in a short period and others were not. They have opened air-lock doors to clear smoke and made other adjustments to ventilation.
UNDERSTANDING SELF-ESCAPE 43 It is clear from investigation reports that communication is important. When possible, there were frequent calls to the surface to get and provide information. As miners with supervisory roles entered and moved about the mine to assess the situations, they provided information to those under- ground. When conditions warranted wearing SCSRs or otherwise restricted verbal communication, miners who were grouped together found ways to communicate, either by using standard head lamp or hand signals or writ- ing in notepads or in the dust. The preceding discussion summarized what the committee learned about the nature of self-escape from past emergencies and disasters (U.S. Department of Labor, 2002, 2003a, 2003b, 2007a, 2007b, 2007c, 2011; West Virginia Office of Minersâ Health, Safety, and Training, 2006; United Mine Workers of America, 2011, n.d.) and from what was reported to the committee. We now discuss how to formally analyze the task of self-escape and why it is important to do. ANALYSIS OF SELF-ESCAPE TASK A critical aspect of preparation for successful self-escape is a thorough analysis of the processes associated with escape. NIOSH reported to the committee that a formal task analysis of the self-escape task from the min- erâs perspective has never been done. Given the limited time and resources available to the committee, a full analysis of self-escape could not be con- ducted. However, it is an important next step toward the development of future training for self-escape. See further discussion in Chapter 6 on the development of training. Comprehensive task analyses describe in detail the behaviors, technol- ogy, and procedures that must be performed and the information that is re- quired in an uncomplicated version of the task, and they provide a reference for identifying training competencies, decision points, key communications, and needed resources. To fully understand the demands placed on miners in a self-escape task, a comprehensive and systematic analysis of the set of decisions and actions during the detection phase preceding escape, during the escape process itself and those following escape would be required. Components of the team and system within which these actions would oc- cur would be included in the analysis. Consideration of system features is a necessary supplement to task analysis and critical incidents analysis and will also inform any needed training. A systematic analysis of the activities that comprise self-escape would yield a number of benefits. First, the concept of self-escape itself would be defined crisply, so that subsequent discussion can focus on a clearly under- stood set of activities and behaviors that occur within a certain period of
44 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES time. Discussion regarding aspects that are unrelated or only marginally related to this task, such as mine rescue, can be treated as such. Second, human behaviors, decision points, information that is required to make good decisions, use of available technology, and critical interac- tions between people can be made clear. When these facets are clear, it is possible to understand the full spectrum of demands that self-escape makes on individuals, as well as the human competencies and technological capa- bilities necessary to effect a successful self-escape. Third, following from the above, once what is necessary is clear, it becomes apparent what is missing to support the miners and key person- nel, especially in the areas of information, training, and technology. These benefits immediately pertain to the self-escape task and are consistent with those noted in recent research by Brannick et al. (2007), Wilson (2007), and Pearlman and Sanchez (2010). There are a number of ways to perform an analysis of a work process (Brannick et al., 2007). The self-escape task, given that it is a relatively rare event in the United States, may be most amenable to analysis by the critical incident technique (Flanagan, 1954). This kind of analysis calls for the specification of incidents of excellent and poor performance in the work process of interestâin this case, self-escape. Job holders and other knowledgeable individuals are asked to specify the context that led up to the incident, what steps the individuals involved took, and what the con- sequences were. The method offers useful information for the development of safety programs and training. A thorough analysis of the self-escape task by this method would re- quire time and systematic methodology. Structured interviews with veterans of past emergencies, disaster survivors, experienced trainers, and other knowledgeable people would have to be conducted; transcripts of post- accident hearings and depositions would have to be combed; the available research would have to be reviewed; and any other pertinent information or data would have to be gleaned for additional insight. Another approach that would be needed to supplement critical inci- dents analysis is what can be termed task analysis. In such an analysis for self-escape, the goal would be to describe the sequence of events, decision points, and actions taken by miners who are confronted with an emer- gency from which escape is mandatory, without regard to successful or unsuccessful outcomes (Brannick et al., 2007). Following the listing of these elements, one can identify and evaluate what are termed the KSAOs: knowledge (e.g., knowledge of location of SCSR caches), skills (e.g., skill in donning an SCSR), abilities (e.g., ability to lead a team in an escape), and other personal attributes (e.g., safety values) needed to accomplish the escape process. It is important to note that every mine disaster has been and will be
UNDERSTANDING SELF-ESCAPE 45 different because of the complexity of a mine emergency situation. For instance, when a mine explosion occurs, the path of destruction cannot be fully anticipated. When a mine fire occurs, the minerâs location is not the only determining factor to a successful escape. For instance, the fire may cause damage that blocks pathways, or ventilation disruption may cause air flow direction to change or methane to build up. For demonstration purposes, we present a rudimentary example that illustrates the concept and benefits of analyzing the task of self-escape and provides a direction on which others can build. The committee chose to ana- lyze self-escape from a fire in a coal mine. In our example, the task is defini- tively bound at the beginning by the onset of the emergency and at the end by the arrival of the miners on the surface. The human activities that occur between these two times are further limited to those activities performed by the miners to escape the mine and those activities performed by the person- nel on the surface to support the minersâ escape. The actions and decisions needed in our example are shown in Figure 3-1. As part of the process, we envisioned challenging conditions and obstacles in order to identify those difficult decision points at which the availability of more information, either before or during the event, the miner(s) could make better decisions. Underlying the entire process of self-escape is the ever-present need for information to inform decision making. Once escape starts, decision mak- ing is influenced by protocol and changing events and therefore must be dynamic, allowing for unexpected circumstances besides the initial hazard. Depending on events, miners need to know many things in order to make good decisions for a successful escape, such as: Where is the fire located? Is the fire spreading and, if so, where? Where are my fellow miners? Is anyone injured or trapped, and, if so, where? Which escapeways are clear of smoke and carbon monoxide? Should we enter a refuge? How far is the next SCSR cache? Which way is outby? Key personnel on the surface also want the answers to many of the same questions. If decision points and information are to be probed, researchers may benefit from using a cognitive task analysis approach (Crandall et al., 2006, provides a very clear explanation). This procedure brings to light the infor- mation needed at a critical decision point, what information was used, and how it was applied. Although this approach is likely to be excessive for all escape decisions, it may be helpful in understanding the decision making at one or two critical junctures, both in the mine and for surface personnel. A key outcome of a detailed systematic task analysis, as indicated above, is the precise identification of KSAOs critical to a successful self- escape. These KSAOs will provide the general blueprint for self-escape training programs. Within this blueprint, the specific training content and instructional design would be derived from a detailed breakdown of tasks that show the stimuli faced by the miner in an emergency, the context and
46 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES problem conditions actions decision points and information go to another line of tasks FIGURE 3-1â Self-escape reference task exercise. NOTE: CO = carbon monoxide; SCSR = self-contained self-rescuers.
UNDERSTANDING SELF-ESCAPE 47
48 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES variations that may be encountered (which would be derived from critical incidents analysis), the information processing needed for decisions (de- rived from a cognitive task analysis), and the responses that should follow. Without this detailed information, training is not likely to be designed successfully. (See Chapter 6 for further discussion on developing training programs.) SYSTEM ASPECTS OF SELF-ESCAPE Over many years the mining industry and its labor force have responded to the evolving technology and the lessons of emergencies to develop roles for the people that would be involved in emergency response and the tech- nologies to aid them. We now turn our attention to describing the current state of persons and technologies that would be involved in self-escape. People When a mine emergency requires the escape of even one miner, many people play important roles. We organize our review of the system of people who contribute to a successful escape in three categories: (1) the individual, (2) the group or team, and (3) the communication centers and responsible persons. While these groups have a significant role during self-escape, we note there are many other people who have roles prior to the need for self-escape. Their roles include establishing and maintaining safe working conditions and preparedness for emergency responses. This requires an ongoing, high level of effort prior to any emergency to create a shared un- derstanding of all parts of any response to nonroutine circumstances. They provide the miners and key surface personnel (e.g., communication centers) with an infrastructure and resources with which they can make decisions and take action during the emergency and with effective training to use those resources. (See Chapter 2 for an overview of current safety practices and Chapter 5 for a discussion of safety culture.) Individual Miners Individual miners enter the mining industry along a well-traveled route of training in the job tasks required by the different technologies and in the safe practices required to protect them and their coworkers. New miners wear a different colored hard hat so they can be recognized by all miners as in training, such as the âred hatsâ in West Virginia (West Virginia Of- fice of Minersâ Health, Safety, and Training, n.d.). This identification lasts a minimum of 6 months (108 shifts) and provides a new miner with time to learn his or her role while being recognized as an apprentice miner. Al-
UNDERSTANDING SELF-ESCAPE 49 though mine operators vary in the training offered to new miners on tech- nology and health and safety, MSHA rules require that all miners receive a minimum of 40 hours of training on health and safety in their initial year and then 8 hours annual retraining thereafter. A recent study by NIOSH found that the majority of coal mine employ- ees are male (96.2 percent). A vast majority is white (96.4 percent). The remaining population in this survey is American Indian and Alaska Native (2.5 percent) and African American (1.2 percent). Based on ethnicity, 1.9 percent of the employee population was identified as Hispanic. The study also found that 93.8 percent have at least a high school education; 16.8 percent reaching an education level beyond high school (National Institute for Occupational Safety and Health, 2012). Although we could not find data on other population characteristics, based on what we heard from industry representatives, we would expect, in terms of mental and physical capabilities, that the work force in under- ground coal mining generally reflects the overall U.S. working population. As such, some miners can be expected to suffer from various chronic con- ditions and diseases, be overweight or obese, be middle-aged or older, and have relatively poor levels of physical fitness, roughly in proportions similar to the overall population of workers. It is reasonable to expect that some miners will be significantly chal- lenged to escape unassisted from a coal mine. From a general safety per- spective, the usual approach in such situations is to make escape as easy as possible and to anticipate that some people will need assistance in escaping. Measures taken to provide this assistance typically include assis- tive equipment and devices, trained personnel within the work unit, rapid intervention teams, rescue equipment, refuge or shelter-in-place facilities, and locator and communication systems or protocols. In developing self-escape strategies, mine operators need to take into consideration the variability in the physical abilities of the miners, the contingencies that arise if a miner becomes injured, and the potential condi- tions created by an emergency. Groups or Teams The group cohesion and social solidarity of coal miners in their typical environment affects escape behavior when a group of miners confronts an emergency (Vaught, 1991; Vaught et al., 2000). For example, Vaught et al. (2000) note âthat when a major fire occurs in an underground coal mine, a new type of group will be formed: an escape group. This group may be made up exclusively of members of a work crew, or it may be a group of individuals who have little or no previous experience working together. [Either way], the escape group must handle tasks very different from those
50 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES that are part of their routine work activities. The physical environment and new emergency tasks will help define group dynamics and decision making during an escapeâ (p. 3). When miners are placed into an emergency situation, they are not likely to function as well as an established, tightly functioning team whose members have been trained to fill key roles and work together in emergency situations. In team effectiveness terms, one can generally expect weak teams and diffused responsibilities. This expectation is in no way a criticism of miners, but rather reflects what is known about creating effective teams to function in hostile and high-hazard settings and occupations. At the same time, miners have also historically worked very well in these situations, and many escapes have been made safely and successfully (see detailed discus- sion on relevant team training for self-escape in Chapter 6). It is important to remember that the training and organization of min- ers is optimized for the production of coal and may not necessarily create an effective team to escape. Moreover, applying principles used to train crisis or emergency personnel (e.g., firefighters or military special operations personnel) may not be an appropriate, practical, or effective strategy. The primary task of coal miners is to produce coal, while the primary task of crisis or emergency personnel is to deal with that crisis or emergency. Fur- thermore, conditions related to personnel selection, practice and rehearsal, team building, situational exposure, and command and control structures cannot be readily duplicated. Creating such teams has proven to be a chal- lenge even in the modern military due to rotating deployments, service rivalries, complex technical systems, and other various incompatibilities. Communication Centers and Responsible Persons Communication centers are instrumental supports to the decision- making processes for miners who are attempting to evacuate the mine. Communication centers may be located immediately at the mineâs surface, or they may be situated as a regional center, operating some distance from the actual mine emergency. Regardless of their location, however, commu- nication centers are an information relay and processing hub. As illustrated in the simplified task analysis delineated above, the information exchanged between miners and communication center personnel (if clearly, correctly, and successfully communicated) informs the choices made by the escaping miners at critical junctions in the process. A communication center must be able to communicate information and update miners when new infor- mation becomes available. Critical in this communication network is the âresponsible personâ (see description in Appendix A), who should ideally be located above ground, have access to information, have the ability to communicate effectively, and be familiar with the emergency response plan
UNDERSTANDING SELF-ESCAPE 51 (ERP). Attention to adequate special training for these individuals needs to be recognized, especially in decision making and other nontechnical skills (see further discussion on training for responsible persons and responsible person teams in Chapter 6). The effectiveness of an escape process will be influenced by the extent to which the communication center roles are clear to all, the personnel have been trained to sort and transmit reliable information, and the available resources have been properly aligned with the information needs of the miners, the emergency personnel, and minersâ families. Consequently, the communication center personnel and their activities during an emergency have to be regarded as an integral part of the minersâ self-escape toolkit. Technologies A range of technologies equip miners to be successful in self-escape. Some of these are part of the technology for routine mining, but most are uniquely designed for health and safety maintenance, as well as self-escape. Current essential technologies that are available to miners and relevant to self-escape include sources of oxygen, gas monitors, wayfinding, com- munications and tracking (including miner-to-miner and miner-to-surface), and refuge chambers. This section discusses each of them and their current limitations. Sources of Oxygen In any mine emergency, access to breathable air is critical to survival. As described above, lack of oxygen and the presence of poisonous gases may occur during a mine emergency. Therefore, the development of tech- nologies that provide sources of oxygen to miners have been a key focus of safety efforts. An overview of currently available oxygen sources is pro- vided in Figure 3-2. Systems that supply either oxygen or air can be split into two types: those that operate on a closed circuit and those that operate on an open circuit or a once-through system. Closed circuit or rebreathing systems provide oxygen and remove moisture and carbon dioxide from the breath. These are normally termed self-contained self-rescuers (SCSRs). The oxygen can be supplied through a chemical reaction initiated by the moisture in a personâs breath. Other SCSRs provide breathable air through a cylinder of compressed oxygen and remove carbon dioxide using either lithium hydroxide or soda lime. Typically, an SCSR weighs 3 to 6 pounds and is worn on a minerâs belt. To use an SCSR, a miner has to insert a mouthpiece into his or her mouth, which significantly hampers or prohibits verbal communication with spoken words. When using an SCSR device, breathing resistance increases over the
52 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES Breathing Apparatus Self-Contained Filter (external (no external atmosphere atmosphere breathed) breathed) Closed-Circuit Open-Circuit Compressed Chemical Liquid Compressed Compressed Supplied Air Oxygen Oxygen Oxygen Air Oxygen Line FIGURE 3-2â Classification of respiratory escape apparatus. SOURCE: Adapted from Bollinger and Schutz (1987). Figure 3-2 operating time, and heat associated with the production of oxygen in the unit can increase to the point where it is severe enough to cause superficial burns. Open-circuit systems provide air or oxygen under positive pressure from a compressed gas cylinder. Compressed air breathing apparatuses (CABAs), which have a full face mask rather than a mouthpiece, are gaining wide acceptance in the Australian mining industry. They offer the capacity to overcome a number of the issues when using a closed-circuit SCSR, including the heat-generated, limited flow rate available, and the userâs inability to communicate with spoken words. CABAs can be quickly refilled by underground miners from banks of cylinders or from a compressed air line without the need for the miner to take it off. CABAs are much heavier than most SCSRs, weighing approximately 20 pounds for a single cylinder and up to 40 pounds for a twin cylinder system. The twin cylinder system can supply air for more than 90 minutes. Currently, CABA (open-circuit) systems are used in the United States in only one mine in New Mexico. It should be noted that a belt-wearable SCSR (closed-circuit device) is neces- sary to reach a CABA storage area, and a transfer from the SCSR to CABA is required. Both open and closed systems have a limited life (10-90 minutes) and require change-out to replacement devices during a prolonged escape or rescue. Their use requires that miners are trained to replace devices dur-
UNDERSTANDING SELF-ESCAPE 53 ing escapes without inhaling ambient air, which could be toxic. This need to change-out also means that additional units need to be strategically positioned around a mine and units in use swapped with them before be- ing exhausted or refilled if applicable. Though the number of changeover stations vary by mine depth and size, it is quite possible that up to five changeovers could be required for a mine worker to exit a larger mine (Brady and Xu, n.d.). Gas Monitoring Real-time gas monitoring is critical in the mining industry, both to alert miners to adverse conditions that have the potential to be controlled and to provide them with essential information during escape (Brady, 2008). Ideally, in an emergency, every miner should know two things: the quality of air at current location and the quality of air in nearby areas (especially along possible escape paths). Information about a minerâs current location is normally achieved through the use of personal gas monitors that can measure the major gases of interest: methane, CO, carbon dioxide, oxygen, and oxygen deficiency. Other gases, such as oxides of nitrogen and sulphur compounds, can be included. These devices are generally issued to supervisors or foremen and maintenance employees and to equipment operators, such as miner operators, roof bolters, and mine examiners. Information about air quality in nearby areas is much harder to acquire. In the United States, fixed gas monitoring is usually located only in the conveyor roadways to detect carbon monoxide from conveyor belt heating. All coal-extracting mining equipment in the United States have methane monitors: on longwalls, they are also located on the shearer, midface, and on the tailgate drives. Stationary CO monitoring equipment is usually located at battery charging stations and diesel equipment and fueling storage locations. Other sources of information can come from fan charts, which are located at air shafts, and in many cases mine seals have monitoring systems in place as well. In Australia, fixed gas monitoring systems are mandatory in return roadways from all operating sections of the mine and unsealed goaf areas,3 as well as at the upcast fan shaft(s) (see, e.g., Queensland Consolidated Regulations, 2001). These systems comprise banks of sensors or tubing that extract the mine air and transport it back to the surface for analysis (a tube bundle system). They continuously monitor the air for methane, CO, carbon dioxide, and oxygen. In addition, in Australia, monitoring of conveyor belts is required, and it is common practice to monitor sealed 3â he T cavity behind the longwall is also known as gob or goaf areas.
54 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES areas for products of oxidation on a regular basis. Monitoring is also becoming more common in intake roadways. Equipment-mounted methane detectors are fitted to a wide range of equipment, usually to ensure that miners do not operate in flammable atmospheres, with automatic cutoffs to remove power before this can happen. Wayfinding Effective wayfinding out of the mine depends on miners knowing where they are and which paths lead to the outside (outby). Wayfinding tech- nologies currently consist of signage, lifelines (metal or, less preferably, polyethylene lines containing tactile directional and resource information), and headlamps for light. Communication technology is also critical for wayfinding. These technologies are vulnerable to explosions, fire, smoke, and other conditions present during escape. For example, headlamps will fail when batteries run down, signage can be blown away, and lifelines destroyed or melted (if made of polyethylene). These technologies can be supplemented by more reliable ones that are hardy under emergency con- ditions. Examples of these include glow sticks and chemical light sources that last 8-12 hours, and passive tactile location and direction indicators embedded in the physical mine environment itself. An example of the lat- ter would be a metal configuration of rivets on the door frames indicating outby direction. In addition, miners could be provided with tools, such as a cane, that would enable them to feel the environment and recognize key features, such as conveyors and overcasts, without endangering themselves. Signage.â In an emergency, knowing oneâs current location and that of the nearest escapeway is vital. Good signage can assist in this process. Given the possibility of low visibility because of smoke or other conditions, any emergency signage needs to be highly reflective and visible under low-light conditions (e.g., a cap lamp). Current regulations have requirements for certain types of signage such as that for SCSR storage (e.g., CFR 75-1714- 2) dictate: A sign with the word âSELF-RESCUERâ or âSELF-RESCUERSâ shall be conspicuously posted at each storage location and shall be made of reflec- tive material. Direction signs made of a reflective material shall be posted leading to each storage place. See Appendix A for further information on the requirements of federal regulations relevant to self-escape.
UNDERSTANDING SELF-ESCAPE 55 FIGURE 3-3â Lifeline indicators. NOTE: For explanation of cone directions, see Appendix A. SOURCE: Title 30 CFR § 75.380 (Illustration 1). Figure 3-3 Lifelines.â Current standard practice for guiding miners through designated Bitmapped escapeways is to install lifelines. Lifelines are fitted with directional cones to indicate the correct traveling route. In low-visibility environments, these cones are intended to be felt through a gloved hand. Current regulations (Title 30 CFR § 75.380) specify such things as minimum distances between cones. They also outline the other types of indicators (tactile shapes) that must be used on a lifeline to indicate such things as a personnel door, refuge alternative on branch line, and SCSR cache on branch line (see Figure 3-3). Vision.â Since low light and heavy smoke are quite possible in mine emer- gencies, miners would need equipment and technologies to protect and supplement vision. Currently, miners rely on their cap lamps for both light- ing to aid vision and as a signaling device (e.g., miners can communicate with each other through head motions). The cap lamp is a technology that is heavily engrained in the culture and behavior of miners. Older lamp tech-
56 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES nology remained largely unchanged for more than 20 years (Lewis, 1986), but cap lamps are now produced with lighter weight batteries, cordless headpieces, and LED (light-emitting diode) lights. Goggles or eyeglasses are another vision technology available to miners. Their primary function is to protect eyes from irritation, especially from dust, smoke, or other particles in the air or damage from toxic gases. They protect minersâ eyes until they can move to an area with a cleaner environ- ment and higher visibility. Currently, miners do not typically have access to goggles or eyeglasses that improve vision (through thermal technologies), but one could imagine ways in which such visual improvements could aid in self-escape. Communication and Tracking Maintaining communications between the mine and the surface and within the mine during normal mine operations is not an easy task. Since mining operations are in constant motion, with work at the face moving more than 50 feet a day, communications systems also have to move with the crew. Systems need to be robust to withstand the mine environmentâ more than 90 percent humidity, potential exposure to corrosive water and dust, electrical properties of coal that can attenuate certain communication frequencies, and a variety of interference sources present (Schiffbauer and Brune, 2006). In addition, any technologies used must be intrinsically safe so they do not create additional hazards underground. In light of these constraints, many mines use a combination of wired and wireless technolo- gies to maintain communication. These systems often rely on mine cables and components that can be destroyed in a mine emergency (Welsh, n.d.). As noted throughout the report, communication between miners and a surface communication center in an emergency is critical so that miners have real-time information essential to address the situation and to achieve safe self-escape. Communication is equally important among the miners, both those in close proximity and those out of the range of visual contact. The 2006 MINER Act required mines to have redundant in-mine commu- nications systems, as well as a system that allows personnel on the surface to determine the current (or the immediate pre-accident) location of un- derground miners. This act also directed mines to provide, within 3 years, both two-way wireless media4 for communication between the surface and 4â rogram P Policy Letter No. P11-V-13 from the U.S. Department of Labor provides guidance for acceptable alternatives to fully wireless communication systems since this technology is not sufficiently developed at this time. âExamples of currently available technologies that may be capable of best approximating a fully wireless communications system include, but are not limited to, leaky feeder, wireless or wired node-based systems, and medium frequency systemsâ (available: http://www.msha.gov/regs/complian/ppls/2011/PPL11-V-13.asp [November 2012]).
UNDERSTANDING SELF-ESCAPE 57 miners underground and electronic tracking systems. MSHA maintains a publicly accessible list of communications and tracking systems that comply with MINER Act requirements. We stress that although technology advances show promise, the failure of such systems remains possible. Consequently, mines should consider low-tech alternatives as backup to record locations and search for miners. In recent years, there has been continuing progress on improving the nature and robustness of these systems to remain intact and functioning in adverse conditions. However, communication technology needs and gaps persist (see Box 3-1). The committee is concerned that many task force recommendations for improving mine safety technology, such as those from BOX 3-1 Communication Technology Needs and Gaps Integrated Primary and Secondary Communication Systems to Improve System Survivability ü Mine-specific modeling and simulation tools ü Improved modeling of the communication links ü Better understanding of secondary systems ü Shared definition and quantitative measure of survivability ü Develop mine-specific modeling tools to be able to assess survivability for: â Any mine configuration â Any installed communication and tracking technology or combinations of technologies â Various types of disasters in various locations within the mine â Various location of miners Primary Systems ⢠Similar to conventional radio handsets ⢠Use small antennas ⢠Wearable devices ⢠Long battery life ⢠Sufficient throughput for general operations Secondary Systems ⢠Unconventional radios ⢠Unconventional signal propagation ⢠Require large antennas (not wearable) ⢠Typically one channel (very low throughput) ⢠Likely more survivable SOURCE: Adapted from a presentation to the committee (Waynert, 2012).
58 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES the West Virginia Mine Safety Technology Task Force (2006) and the Mine Safety Technology and Training Commission (2006), have remained âin progressâ since they were made, now more than 5 years ago. Refuge Chambers Refuge chambers originated in South Africa in the 1970s, and they have been common in the metalliferous mining industry worldwide for more than 20 years (Underground Coal Mining Safety Research Collaboration, 2003). In 2006, the MINER Act required every operator to provide refuge alternatives and specified the components to be included. Refuge chambers must be approved by MSHA. The specifications indicate that refuges must supply breathable air to sustain each person for 96 hours, refuges must have sufficient capacity for all persons underground, refuges must be located within 1,000 feet of working areas, and refuges must be spaced within 1 hour in travel time to an outby area. (See Appendix A for further details on refuge chamber requirements.) The obvious risks of refuge chambers include the air supply being exhausted before escape; air supply that does not survive the incident or subsequent heat; and, if communications are down, the surface personnel may not know miners are sheltering in the refuge chamber. There would need to be a rigorous maintenance and inspection regime to ensure the refuge chambers were operable in the event of an emergency. Functional Design of Technologies It is important to view technology as part of any self-escape system. A human-systems integration approach typically assigns primary importance to the person or persons in the system. As such, it uses well-established and validated human- (or user-) centered design processes (Norman, 1993; Wickens et al., 2004). Although modern technological advances may be awe inspiring, their incorporation into the mining environment may not be in the best interest of the miner. A minerâs body has a finite amount of space and strength to carry gadgets. In emergency situations, a miner should not be expected to monitor, understand, and synthesize data from multiple devices presented in multiple formats. In considering options for design improvements of any technology or tool, an analysis should incorporate human-centered design that takes into consideration human factors, such as natural behavior tendencies and ease of technology use in addition to the tasks required to self-escape. In order for any new technologies to be effective, there are some general requirements which must be met before they will be accepted in the mining environment. Size and weight are critical factors if the technologies are to
UNDERSTANDING SELF-ESCAPE 59 be used by individual miners during self-escape. A person can only wear or carry a limited amount of equipment in anticipation of an emergency, and if it is heavy or bulky, miners will not readily agree to wear or carry them. These technologies must also be easy to deploy and easy to understand. If miners do not know how to use the technology or do not trust that it will provide them with useful information or protections, they are less likely to use it. We have identified some functional characteristics of technology that are needed and likely to enhance the transfer of information needed to facilitate and optimize self-escape: ⢠Tracking: It is critical for the hazard management purposes to un- derstand who is in a mine and where they are located within the mine at any given time. This information should be available to the surface communication center and this information should also be transmissible to fellow miners so that the miners can congregate and form teams in order to optimize their self-escape capabilities. ⢠Communication: Communication during an emergency that is suc- cinct and effective is essential. Thus, natural verbal communication should be enabled between the surface communication center and the miners, as well as between all miners within an area. Miners must be able to communicate with each other when they are in close proximity to each other as well as when they are within rea- sonable distance to each other (e.g., nearby sections). Any devices should be wireless, lightweight, easily accessible, and worn on the miner. ⢠Supplied Air: Sources of oxygen are critically important in po- tentially toxic environments. Supplied air devices (e.g., SCSRs) should be easy to use and easily accessible. Supplied air devices need to be updated so that they not only permit verbal communi- cation but also accommodate a variety of physical features pres- ent within the miner population. Along with training, the devices should be designed with human-factors principles in mind so that they are easily donned and activated. These devices should also consider the human interface in that they should be less cum- bersome, provide straps for convenient carrying (e.g., shoulder straps), and provide information about remaining safe air supply time to the user. ⢠Atmosphere Monitoring: All miners should have access to informa- tion regarding quality of the atmosphere especially during an emer- gency. They should have timely and easy to understand information that easily alerts them to any dangerous atmospheric conditions that are present or developing.
60 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES ⢠Signage and Other Landmarks: Standard signage and other land- marks within a mine can help orient a miner during an emergency. Those that can be identified even under poor visibility conditions are necessary to facilitate effective self-escape. An alarm or strobe could serve as an orienting landmark that could be remotely acti- vated to indicate the location of the primary and/or best exit from the mine. ⢠Wayfinding: Technology needs to be developed that tracks the min- ersâ locations within the mine, information about air quality, fire sources, as well as other hazards, and incorporates this information into an easy to interpret display to enhance wayfinding. ⢠Directional Technology: Directional information that is usable even under poor visual and communication-deficient conditions is needed to direct miners to escapeways, rescue chambers, additional supplied air devices, man doors, etc. Underground cues to such locations can be provided with simple technology such as lifelines and passive tactile indicators embedded in the physical mine en- vironment itself to provide real-time information to an escaping miner. However, it is important that such directional technologies be designed with human-factors principles in mind so that the miner can most effectively and accurately interpret the directional signals provided by these technologies. ⢠Vision Enhancement: Vision-enabling technology is needed to per- mit miners to see though smoke as much as possible. RECOMMENDATIONS The mining industry has spent nearly a billion dollars on emergency preparations since 2006 and continues to look for even better technologies. Several areas have been identified as needing upgrades and cooperative efforts are under way that include minersâ representatives, operators, tech- nology providers, and the government. Given the challenges facing a miner under emergency situations, it is imperative that the human-technology interface be as efficient and effortless as possible. It is also important that technology survivability during an emergency is given attention in development. As discussed in Chapter 2, the committee heard from many stakehold- ers that the current technology regulatory and approval process in the United States appears to be a deterrent to rapid technological innovation and access to global markets, which hampers the commercial viability of innovation. The operational requirements for emergency supplies of breathable air are in need of revision. An essential component of this interface is to ensure
UNDERSTANDING SELF-ESCAPE 61 a supply of breathable air for self-escape that will function in a variety of atmospheric conditions. For example, an SCSR should ensure performance against all harmful gases, as well as an adequate supply of breathable air in oxygen-deficient atmospheres. Additionally, filtered devices that only protect against carbon monoxide and do not supply breathable air (used in a small number of mines) should be removed entirely unless specifically justified. RECOMMENDATION 2: The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Admin- istration should review their operational requirements for emergency supplies of breathable air. Furthermore, NIOSH should allocate funds for research and development to improve the functionality of emer- gency supplies of breathable air, with special focus devoted to resolving a wide range of issues including ⢠verbal communication, ⢠positive pressure, ⢠facial hair, ⢠device weight and size minimization, ⢠device changeover or air replenishment in toxic environments, ⢠fit testing where applicable, and ⢠adequate vision through clearing or removal of condensation. RECOMMENDATION 3: The National Institute for Occupational Safety and Health, the Mine Safety and Health Administration, and technology companies should accelerate efforts to develop technologies that enhance self-escape. These technologies should use human-centered design principles with specific attention to facilitating improved situ- ational awareness and decision making. The technologies should in- clude, but are not limited to: ⢠communications, both miner to miner and miner to surface; ⢠real-time gas monitors that are appropriate for all miners; ⢠fail-safe tracking that is hardened and survivable; and ⢠multifunction devices that combine technology to reduce physical burden and excessive demands on attention. RECOMMENDATION 4: The National Institute for Occupational Safety and Health and the Mine Safety and Health Administration should reexamine their technology approval and certification processes to ensure they are not deterring innovation in relation to self-escape
62 IMPROVING SELF-ESCAPE FROM UNDERGROUND COAL MINES technologies that are used in other industrial sectors and global mar- kets. They should collaborate in convening a joint industry, labor, and government working group to identify a range of mechanisms to reduce or eliminate any barriers to technology approval and certification, which should include exploring opportunities to cooperate with other international approval organizations to harmonize U.S. and interna- tional standards without compromising safety.