Lisa Steiner

Human factors for the design, operation, and maintenance of mining equipment

Through coverage of topics such as equipment design, operations and maintenance, manual tasks, workstation design, physical environment, this book explores what human factors are all about and their critical importance to safety, health, and efficiency in the minerals industry.

Toward a Typology of Dynamic and Hazardous Work Environments

The most hazardous work environments share one feature in common: constant change. Many different, but constantly changing hazards are found in agriculture, construction, mining, and transport. This dynamic feature of workplace hazards varies by: (1) degree of control, (2) predictability, (3) visibility, (4) movement, and (5) degree of speed and force. In some cases the actions of the dynamic hazards are required for production to take place, and in many cases, several different hazards may overlap and interact. Finally, whether intentional or unintentional, some dynamic hazards are human generated. These are some of the features that distinguish dynamic and hazardous work environments across a variety of industries. The authors propose a preliminary typology of dynamic and hazardous work environments, along with a schema to systematically observe the dynamic characteristics of these hazards. The implications of this typology are considered with respect to worker training, hazard awareness, and safe work practices. For example, the implementation of the Hierarchy of Control is shown to require active worker involvement at every level in the hierarchy, except where an environmental hazard has been completely eliminated.

Injuries Associated With Continuous Miners, Shuttle Cars, Load-Haul-Dump and Personnel Transport in New South Wales Underground Coal Mines

Abstract In the three years to June 2005, 959 injuries associated with continuous miners (CMs), shuttle cars (SCs), load–haul–dump and personnel transport (PT) were reported by NSW underground coal mines, comprising 23% of all injuries reported. The present paper reports an analysis of the narrative field accompanying these reports to determine opportunities for controlling injury risks. The most common combinations of activity and mechanism were: strain while handling CM cable (96 injuries); caught between or struck by moving parts while bolting on a CM (86 injuries); strains while bolting on CM (54 injuries); and slipping off a CM during access, egress or other activity (60 injuries). For the other equipment considered, the common injury mechanism was the vehicle running over a pothole or other roadway abnormality causing the driver or passengers to be injured (169 injuries). Potential control measures include: monorails for CM services; hydraulic cable reelers; handrails on CM platforms; redesign of CM platforms and bolting rigs to reduce reach distances during drilling and bolting; improvements to guarding of bolting controls; standardisation and shape coding of bolting controls; two handed fast feed; improvements in underground roadway maintenance, vehicle suspension, visibility and seating; and pedestrian proximity warning devices.

Directional control-response relationships for mining equipment

A variety of directional control-response relationships are currently found in mining equipment. Two experiments were conducted in a virtual environment to determine optimal direction control-response relationships in a wide variety of circumstances. Direction errors were measured as a function of control orientation (horizontal or vertical), location (left, front, right) and directional control-response relationships. The results confirm that the principles of consistent direction and visual field compatibility are applicable to the majority of situations. An exception is that fewer direction errors were observed when an upward movement of a horizontal lever or movement of a vertical lever away from the participants caused extension (lengthening) of the controlled device, regardless of whether the direction of movement of the control is consistent with the direction in which the extension occurs. Further, both the control of slew by horizontally oriented controls and the control of device movements in a frontal plane by the perpendicular movements of vertical levers were associated with relatively high rates of directional errors, regardless of the directional control-response relationship, and these situations should be avoided. Statement of Relevance:The results are particularly applicable to the design of mining equipment such as drilling and bolting machines, and have been incorporated into MDG35.1 Guideline for bolting & drilling plant in mines (Industry & Investment NSW, 2010). The results are also relevant to the design of any equipment where vertical or horizontal levers are used to control the movement of equipment appendages, e.g. cranes mounted to mobile equipment and the like.

Reducing control selection errors associated with underground bolting equipment.

Selecting the incorrect control during the operation of underground bolting and drilling equipment causes serious injuries. Shape coding and the layout of dual control banks are two aspects of control design which require further examination. The aims of this research were: (i) to determine whether arbitrary shape coding was effective in reducing selection error rates in a virtual analogy of roof-bolting; and (ii) to determine whether any advantages exist for mirror or place layouts for dual control situations in this situation. Two experiments were conducted to address these questions. No benefits of arbitrary shape coding were evident while control location remained constant. When control location was altered, shape coding did provide a significant reduction in selection error rate. No differences between mirror or place arrangements were detected and this question remains open.

Directional control-response compatibility relationships assessed by physical simulation of an underground bolting machine

Objective: The authors examine the pattern of direction errors made during the manipulation of a physical simulation of an underground coal mine bolting machine to assess the directional control-response compatibility relationships associated with the device and to compare these results to data obtained from a virtual simulation of a generic device. Background: Directional errors during the manual control of underground coal roof bolting equipment are associated with serious injuries. Directional control-response relationships have previously been examined using a virtual simulation of a generic device; however, the applicability of these results to a specific physical device may be questioned. Method: Forty-eight participants randomly assigned to different directional control-response relationships manipulated horizontal or vertical control levers to move a simulated bolter arm in three directions (elevation, slew, and sump) as well as to cause a light to become illuminated and raise or lower a stabilizing jack. Directional errors were recorded during the completion of 240 trials by each participant. Results: Directional error rates are increased when the control and response are in opposite directions or if the direction of the control and response are perpendicular. The pattern of direction error rates was consistent with experiments obtained from a generic device in a virtual environment. Conclusion: Error rates are increased by incompatible directional control-response relationships. Application: Ensuring that the design of equipment controls maintains compatible directional control-response relationships has potential to reduce the errors made in high-risk situations, such as underground coal mining.

Predicting system interactions in the design process.

Almost every process has a predecessor, and studying the predecessor helps to define needs and shortcomings to be addressed in the new design. It also suggests what information is needed by the users in order for them to be able to operate safely and effectively. The end users of a system can provide important feedback to better evaluate the current and proposed designs. When new technology is introduced into a system, mishaps may occur before it is realized that human-system interactions were not considered adequately in the design process. A systematic methodology to evaluate the causes of these injuries and to develop remedial recommendations can enhance safety. This paper illustrates how such an approach was used to assess remote machine operation in underground coal mines.

Visual feedback system to reduce errors while operating roof bolting machines.

PROBLEM Operators of roof bolting machines in underground coal mines do so in confined spaces and in very close proximity to the moving equipment. Errors in the operation of these machines can have serious consequences, and the design of the equipment interface has a critical role in reducing the probability of such errors. METHODS An experiment was conducted to explore coding and directional compatibility on actual roof bolting equipment and to determine the feasibility of a visual feedback system to alert operators of critical movements and to also alert other workers in close proximity to the equipment to the pending movement of the machine. The quantitative results of the study confirmed the potential for both selection errors and direction errors to be made, particularly during training. RESULTS Subjective data confirmed a potential benefit of providing visual feedback of the intended operations and movements of the equipment. IMPACT This research may influence the design of these and other similar control systems to provide evidence for the use of warning systems to improve operator situational awareness.

Stability evaluation of extended cut mining in underground coal mines

Abstract The trend in underground room-and-pillar coal mining is to employ remote-control continuous mining machines to take extended cuts of 40 ft or more. Extended cutting can create additional worker safety hazards. To address these hazards, a combination of statistical analysis, underground investigations, and humerical modeling are being conducted. Statistical analysis of extended cut use, roof fall accidents and fatalities delineated the extent of the problem in U.S. coal mines. Underground studies addressed the roof stability consequences of employing extended cutting. The stress profiles, pillar stability, and safety factors of alternative mine layouts that eliminate unsafe continuous miner operator positioning during the remote-control mining of crosscuts were addressed using displacement-discontinuity modeling and programs such as LAMODEL (Laminated Model) and ARMPS (Analysis of Retreat Mining Pillar Stability).

Shape-Coding and Length-Coding as a Measure to Reduce the Probability of Selection Errors During the Control of Industrial Equipment

OCCUPATIONAL APPLICATIONS Shape-coding and length-coding of control levers may have limited benefits for the prevention of selection errors during operation of roof-bolting machines and other industrial equipment. Any benefits of arbitrary shape-coding or length-coding for reducing selection errors are likely to be restricted to situations in which the arrangement of controls in relation to the participant is subsequently altered in some way, such as the operator moving from one machine to another with a different control layout. If shape-coding is employed, measures should be taken to ensure that the relationship between shape and function remains consistent across similar equipment and that the relationship between shape and function cannot be altered in error during maintenance. TECHNICAL ABSTRACT Rationale: Underground coal mining is one of the most hazardous industrial environments, and roof-bolting machine operators are the most at-risk occupation in underground coal mining. Many examples of industrial equipment, including bolting machines used in underground coal mines, are operated via a bank of levers that control different machine functions and movements. Errors in the use of these controls are a cause of serious injuries. Purpose: A recent design guideline for underground bolting equipment has specified the use of arbitrary shape-coding for principal equipment functions with the aim of reducing injuries caused by operators inadvertently operating the wrong lever (a selection error). Three experiments were conducted to provide further insight to the use of control-coding. Methods: Sixty-four individuals participated in three experiments. Each participant operated a physical simulation of a single-boom roof-bolter machine via five levers in either shape-coded, length-coded, or identical handle conditions. In two experiments, the location of the controls was changed half-way through the experiment. Selection error rate data were collected. Results: When operators are not under time pressure, their attention is not divided, and they are able to view the controls they are manipulating, any benefits of arbitrary shape-coding or length-coding for reducing selection errors are likely to be restricted to situations in which the arrangement of controls in relation to the participant is subsequently altered. Conclusions: If shape-coding is employed, measures should be taken to ensure that the relationship between shape and function remains consistent and that maintenance errors, such as reversing handle shapes, are prevented.