Whole-body vibration associated with underground coal mining equipment in Australia

Environmental and logistical difficulties associated with obtaining whole-body vibration measurements from mobile equipment during operation in underground coal mines have hampered attempts to assess the potential vibration exposures associated with the use of such equipment. An alternative measurement technique was used to gather data from mobile equipment during normal operation at three low-methane coal mines and to estimate the possible magnitude of benefit of three control measures. 188 long duration measurements were obtained from shuttle cars (N = 142, median measurement duration = 3.2 h); personnel transport (N = 24, median measurement duration = 2.4 h); and materials transport vehicles (N = 22, median measurement duration = 1.8 h). Whole-body vibration amplitudes either within or exceeding the ISO health guidance caution zone were consistently measured. In particular, shuttle cars demonstrated whole-body vibration amplitudes which frequently exceeded the health guidance caution zone. The potential effects of roadway maintenance, decreased vehicle speed, and shuttle car seat replacement were found to be practically meaningful.

A Human-Centered Approach to the Redesign of a Bitumen Trailer

An electric heat-in-transit tanker (bitumen trailer) revolutionized the operation and design of bituminous tankers. It was developed using human-centered approaches and design philosophy, concepts, methods, and tools previously used in the mining industry. Task-based analysis was useful to contextualize opportunities and hazards. The new tanker improved efficiency in transit, reduced risk for exposure to hot bituminous product, improved access, reduced on-road travel time and risk for fatigue, optimized work performance, and challenged regulators to redefine safe transit requirements. The design process was opportunity based and highlighted the need to shift philosophy to consider performance-based needs of operators, not just equipment.

Whole-Body Vibration Associated with Dozer Operation at an Australian Surface Coal Mine

Bulldozers are used extensively on surface mine sites and have been previously identified as being associated with high amplitude whole-body vibration exposures. Previous investigations of this equipment have involved either a very small number of measurements, or measurements of very short duration (or both); or the data obtained were incompletely reported. This research reports 69 measurements (median duration 440 min) obtained from 15 different dozers during operation at a surface coal mine. More than one-third of vertical vibration measurements exceeded the ISO2631.1 Health Guidance Caution Zone when expressed as VDV(8). Considerable variability in measurement amplitudes was found. This was also true within measurements obtained from the same dozers on different shifts suggesting, by a process of elimination, that the remaining variability in whole-body vibration amplitude is a function of some combination of task characteristics, geology, and operator behaviour; rather than equipment-related variability, such as maintenance, suspension, seating, or track design. Short-comings in the evaluation methods provided by ISO2631.1 are highlighted.

Participatory ergonomics: Evidence and implementation lessons

Participatory ergonomics programs have been proposed as the most effective means of eliminating, or redesigning, manual tasks with the aim of reducing the incidence of occupational musculoskeletal disorders. This review assesses the evidentiary basis for this claim; describes the range of approaches which have been taken under the banner of participatory ergonomics in diverse industries; and collates the lessons learned about the implementation of such programs.

Assessing colonoscopic inspection skill using a virtual withdrawal simulation: a preliminary validation of performance metrics

BACKGROUND

The effectiveness of colonoscopy for diagnosing and preventing colon cancer is largely dependent on the ability of endoscopists to fully inspect the colonic mucosa, which they achieve primarily through skilled manipulation of the colonoscope during withdrawal. Performance assessment during live procedures is problematic. However, a virtual withdrawal simulation can help identify and parameterise actions linked to successful inspection, and offer standardised assessments for trainees.

METHODS

Eleven experienced endoscopists and 18 endoscopy novices (medical students) completed a mucosal inspection task during three simulated colonoscopic withdrawals. The two groups were compared on 10 performance metrics to preliminarily assess the validity of these measures to describe inspection quality. Four metrics were related to aspects of polyp detection: percentage of polyp markers found; number of polyp markers found per minute; percentage of the mucosal surface illuminated by the colonoscope (≥0.5 s); and percentage of polyp markers illuminated (≥2.5 s) but not identified. A further six metrics described the movement of the colonoscope: withdrawal time; linear distance travelled by the colonoscope tip; total distance travelled by the colonoscope tip; and distance travelled by the colonoscope tip due to movement of the up/down angulation control, movement of the left/right angulation control, and axial shaft rotation.

RESULTS

Statistically significant experienced-novice differences were found for 8 of the 10 performance metrics (p's < .005). Compared with novices, experienced endoscopists inspected more of the mucosa and detected more polyp markers, at a faster rate. Despite completing the withdrawals more quickly than the novices, the experienced endoscopists also moved the colonoscope more in terms of linear distance travelled and overall tip movement, with greater use of both the up/down angulation control and axial shaft rotation. However, the groups did not differ in the number of polyp markers visible on the monitor but not identified, or movement of the left/right angulation control. All metrics that yielded significant group differences had adequate to excellent internal consistency reliability (α = .79 to .90).

CONCLUSIONS

These systematic differences confirm the potential of the simulated withdrawal task for evaluating inspection skills and strategies. It may be useful for training, and assessment of trainee competence.

A novel training device for tip control in colonoscopy: preliminary validation and efficacy as a training tool

Background

Effective control of the colonoscope tip is one of the most fundamental components of colonoscopy skill. Mastering fine tip control can be problematic for novice trainees, yet no validated training regimes exist for developing this specific skill component in isolation. We aimed to conduct a preliminary validation of a novel training device for colonoscopic tip control, and to assess its efficacy as a training tool.

Methods

In study 1 (validation), 13 experienced colonoscopists and 16 novices used a colonoscope to accurately track 28 targets on each of four concave “training surfaces” as quickly as possible, and we compared their performance. In study 2 (pre–post-training study), another 16 novices were tested before and after a six-session training program. In both studies, the main outcome measurements were completion time (measured automatically by the device) and variability of individual performance (the SD of each individual’s completion times across trials).

Results

Compared with novices, experienced colonoscopists were faster (P < 0.0001) and their performances less variable (P < 0.0001). With training, novices became faster (P < 0.0001) and more consistent (P = 0.003), and these improvements also generalized to novel training surfaces (P’s < 0.01). After training, the novices’ tip control performance was indistinguishable from that of the experienced colonoscopists (P’s > 0.05). The composite measures of completion time used in both studies all had acceptable to excellent internal consistency reliability (α’s ranged from 0.72 to 0.93).

Conclusions

We found that performance measures derived from using the device to assess skill can discriminate between experienced colonoscopists and novices in terms of their ability to control and guide the colonoscope tip precisely, providing preliminary evidence to support the construct validity of the metrics. The device is also an effective training tool for this fundamental component of colonoscopy skill.

The efficacy of training insertion skill on a physical model colonoscopy simulator

Background and study aims: Prior research supports the validity of performance measures derived from the use of a physical model colonoscopy simulator - the Kyoto Kagaku Colonoscope Training Model (Kyoto Kagaku Co. Ltd., Kyoto, Japan) - for assessing insertion skill. However, its use as a training tool has received little research attention. We assessed the efficacy of a brief structured program to develop basic colonoscope insertion skill through unsupervised practice on the model. Participants and methods: This was a training study with pretesting and post-testing. Thirty-two colonoscopy novices completed an 11-hour training regime in which they practiced cases on the model in a colonoscopy simulation research laboratory. They also attempted a series of test cases before and after training. For each outcome measure (completion rates, time to cecum and peak force applied to the model), we compared trainees' post-test performance with the untrained novices and experienced colonoscopists from a previously-reported validation study. Results: Compared with untrained novices, trained novices had higher completion rates and shorter times to cecum overall (Ps < .001), but were out-performed by the experienced colono-scopists on these metrics (Ps < .001). Nevertheless, their performance was generally closer to that of the experienced group. Overall, trained novices did not differ from either experience-level comparison group in the peak forces they applied (P > .05). We also present the results broken down by case. Conclusions: The program can be used to teach trainees basic insertion skill in a more or less self-directed way. Individuals who have completed the program (or similar training on the model) are better prepared to progress to supervised live cases.

Assessment of colorectal polyp recognition skill: development and validation of an objective test

BACKGROUND

The quality of colonoscopy is known to vary. The extent to which colonoscopists can recognize the presence of subtle colorectal lesions by visually distinguishing them from the surrounding mucosa (i.e., polyp recognition skill) may be one of several attributes that influence polyp detection rates. The aim of the present study was to develop and validate the first objective test of polyp recognition skill.

METHODS

Validation study. Twenty-eight experienced colonoscopists and eighty novices took a preliminary 280-item computer-based polyp recognition test. Items were genuine endoscopic images which participants assessed for the presence of "likely polyps." Half included clinically identified polyps. Participants clicked on a suspected lesion or a button marked "no likely polyp", and the main outcome measures were accuracy and response latency. The best items were selected for the final 50-item test.

RESULTS

In the preliminary test, experienced colonoscopists correctly identified more polyps than novices (P < .0001) and better discriminated between clinically identified polyps and non-polyp features (as measured by d', P < .0001). For polyp items, the experienced group also responded faster (P < .01). Effect sizes were large for accuracy (Cohen's d = 3.22) and d' (Cohen's d = 3.22). The 50 final test items produced comparable results for accuracy, d', and response latency. For both versions of the test, score scale reliability was high for both polyp and non-polyp items (α = .82 to .97).

CONCLUSIONS

The observed experienced-novice differences support the construct validity of the performance measures derived from the tests, indicating that polyp recognition skill can be quantified objectively. The final test may potentially be used to assess trainees, but test sensitivity may be insufficient to make fine-grained distinctions between different skill levels among experienced colonoscopists. More sensitive future tests may provide a valuable supplement to clinical detection rates, allowing objective comparisons between skilled colonoscopists.

Identification of Underlying Assumptions is an Integral Part of Research: An Example from Motor Control

Research is inherently subjective. It is conducted within a theoretical and methodological framework, the validity of which depends on underlying assumptions about the nature of reality and knowledge. The interpretation of one's own data, and the evaluation of the data interpretation of others, requires assessment of these underlying philosophical assumptions. We contend that while examination of philosophical assumptions is demonstrably an integral part of research, it is one which has largely been neglected in experimental psychology because researchers have rarely explicitly identified their ontological and epistemological assumptions. A contemporary debate in experimental psychology, that between representational and non-representational approaches to understanding the control of movement, is discussed to illustrate the influence such ontological and epistemological assumptions have upon methodological choices and upon the development and evaluation of theory.

Improving Mining Equipment Safety Through Human-Centered Design

The need for human-centered design in the mining industry to help develop safe and fit-for-purpose equipment is first described. A tool that was specifically developed for mobile mining equipment by the authors and colleagues is introduced; it combines the application of participatory ergonomics, qualitative risk management, and safe design. A case study using this tool for mobile mining equipment access and egress is then presented. The case study shows that focusing on end users and their tasks by means of a structured, human-centered process can help to produce safer redesigns of mining equipment.

Long duration measurements of whole-body vibration exposures associated with surface coal mining equipment compared to previous short-duration measurements

Previous measurements of whole-body vibration associated with earth-moving equipment at surface coal mines have highlighted the significance of the hazard. Considerable variability in measurement amplitudes, even within the same equipment type operated at the same site, has been noted. However, the measurements have previously been undertaken for relatively short durations. Fifty-nine measurements were collected from a range of earth-moving equipment in operation at a surface coal mine. Measurement durations ranged from 100-460 min (median = 340 min). The results indicate that the measurements previously observed are not an artifact of the relatively short durations and confirm that operators of dozers and off-road haul trucks, in particular, are frequently exposed to vertical whole-body vibration levels which lie within, or above, the Health Guidance Caution Zone defined by ISO2631.1. Further investigations are justified to identify opportunities for reducing operators' exposure to high amplitude vibrations.

A competency framework for colonoscopy training derived from cognitive task analysis techniques and expert review

BACKGROUND

Colonoscopy is a difficult cognitive-perceptual-motor task. Designing an appropriate instructional program for such a task requires an understanding of the knowledge, skills and attitudes underpinning the competency required to perform the task. Cognitive task analysis techniques provide an empirical means of deriving this information.

METHODS

Video recording and a think-aloud protocol were conducted while 20 experienced endoscopists performed colonoscopy procedures. "Cued-recall" interviews were also carried out post-procedure with nine of the endoscopists. Analysis of the resulting transcripts employed the constant comparative coding method within a grounded theory framework. The resulting draft competency framework was modified after review during semi-structured interviews conducted with six expert endoscopists.

RESULTS

The proposed colonoscopy competency framework consists of twenty-seven skill, knowledge and attitude components, grouped into six categories (clinical knowledge; colonoscope handling; situation awareness; heuristics and strategies; clinical reasoning; and intra- and inter-personal).

CONCLUSIONS

The colonoscopy competency framework provides a principled basis for the design of a training program, and for the design of formative assessment to gauge progress towards attaining the knowledge, skills and attitudes underpinning the achievement of colonoscopy competence.

An iOS Application for Evaluating Whole-body Vibration Within a Workplace Risk Management Process

Workplace management of whole-body vibration exposure requires systematic collection of whole-body vibration data in conjunction with the numerous variables which influence vibration amplitudes. The cost and complexity of commercially available measurement devices is an impediment to the routine collection of such data by workplaces. An iOS application (WBV) has been developed which allows an iPod Touch to be used to measure whole-body vibration exposures. The utility of the application was demonstrated by simultaneously obtaining 98 pairs of whole-body vibration measurements from both the iPod Touch application and a commercially available whole-body vibration device during the operation of a variety of vehicles and mobile plant in operation at a surface coal mine. The iOS application installed on a fifth-generation iPod Touch was shown to provide a 95% confidence of +/- 0.077 m/s(2) r.m.s. constant error for the vertical direction. Situations in which vibration levels lay within the ISO2631.1 health guidance caution zone were accurately identified, and the qualitative features of the frequency spectra were reproduced. The low cost and relative simplicity of the application has potential to facilitate its use as a screening tool to identify situations in which musculoskeletal disorders may arise as a consequence of exposure to whole-body vibration.

Concurrent 3-D sonifications enable the head-up monitoring of two interrelated aircraft navigation instruments

OBJECTIVE

The aim of this study was to enable the head-up monitoring of two interrelated aircraft navigation instruments by developing a 3-D auditory display that encodes this navigation information within two spatially discrete sonifications.

BACKGROUND

Head-up monitoring of aircraft navigation information utilizing 3-D audio displays, particularly involving concurrently presented sonifications, requires additional research.

METHOD

A flight simulator's head-down waypoint bearing and course deviation instrument readouts were conveyed to participants via a 3-D auditory display. Both readouts were separately represented by a colocated pair of continuous sounds, one fixed and the other varying in pitch, which together encoded the instrument value's deviation from the norm. Each sound pair's position in the listening space indicated the left/right parameter of its instrument's readout. Participants' accuracy in navigating a predetermined flight plan was evaluated while performing a head-up task involving the detection of visual flares in the out-of-cockpit scene.

RESULTS

The auditory display significantly improved aircraft heading and course deviation accuracy, head-up time, and flare detections. Head tracking did not improve performance by providing participants with the ability to orient potentially conflicting sounds, suggesting that the use of integrated localizing cues was successful. Conclusion: A supplementary 3-D auditory display enabled effective head-up monitoring of interrelated navigation information normally attended to through a head-down display.

APPLICATION

Pilots operating aircraft, such as helicopters and unmanned aerial vehicles, may benefit from a supplementary auditory display because they navigate in two dimensions while performing head-up, out-of-aircraft, visual tasks.

Whole-body vibration exposure of haul truck drivers at a surface coal mine

Haul truck drivers at surface mines are exposed to whole-body vibration for extended periods. Thirty-two whole-body vibration measurements were gathered from haul trucks under a range of normal operating conditions. Measurements taken from 30 of the 32 trucks fell within the health guidance caution zone defined by ISO2631-1 for an 8 h daily exposure suggesting, according to ISO2631-1, that "caution with respect to potential health risks is indicated". Maintained roadways were associated with substantially lower vibration amplitudes. Larger trucks were associated with lower vibration levels than small trucks. The descriptive nature of the research, and small sample size, prevents any strong conclusion regarding causal links. Further investigation of the variables associated with elevated vibration levels is justified.

RELEVANCE TO INDUSTRY

The operators of mining equipment such as haul trucks are exposed to whole-body vibration amplitudes which have potential to lead to long term health effects. Systematic whole-body vibration measurements taken at frequent intervals are required to provide an understanding of the causes of elevated vibration levels and hence determine appropriate control measures.

Control order and visuomotor strategy development for joystick-steered underground shuttle cars

OBJECTIVE

In this simulator-based study, we aimed to quantify performance differences between joystick steering systems using first-order and second-order control, which are used in underground coal mining shuttle cars. In addition, we conducted an exploratory analysis of how users of the more difficult, second-order system changed their behavior over time.

BACKGROUND

Evidence from the visuomotor control literature suggests that higher-order control devices are not intuitive, which could pose a significant risk to underground mine personnel, equipment, and infrastructure.

METHOD

Thirty-six naive participants were randomly assigned to first- and second-order conditions and completed three experimental trials comprising sequences of 90 degrees turns in a virtual underground mine environment, with velocity held constant at 9 km/h(-1). Performance measures were lateral deviation, steering angle variability, high-frequency steering content, joystick activity, and cumulative time in collision with the virtual mine wall.

RESULTS

The second-order control group exhibited significantly poorer performance for all outcome measures. In addition, a series of correlation analyses revealed that changes in strategy were evident in the second-order group but not the first-order group.

CONCLUSION

Results were consistent with previous literature indicating poorer performance with higher-order control devices and caution against the adoption of the second-order joystick system for underground shuttle cars.

APPLICATION

Low-cost, portable simulation platforms may provide an effective basis for operator training and recruitment.

Developing computer competencies for eWorkers within call centres

High rates of work related musculoskeletal discomfort (WRMSD) associated with long-hours of computer work are considered a significant occupational health problem. However, to date few training programs aim to develop the multidisciplinary skills required for self-management of WRMSD risk factors. This paper seeks to provide a background to, and illustrate the significance of, this issue. Management strategies, training elements and methods recommended within the literature to build the required work skills for increased self-management of WRMSD are discussed. The inclusion of two case studies investigating the impact of training methods on levels of WRMSD illustrates how the application of new training strategies may improve WRMSD outcomes. The first case-study trialling a pre-existing office ergonomic checklist revealed training improved knowledge and awareness, but failed to change work behaviours or effect levels of WRMSD. The second case study investigated the impact of training providing additional knowledge and demonstrating 'how-to' apply recommendations at the workstation. Outcomes of this skill-based program included the collaborative development of training elements, increased trainee engagement, and a significant reduction in reported levels of WRMSD. These findings suggest training designed to develop multidisciplinary work skills or competencies may be a strategy for the management of occupational musculoskeletal discomfort amongst computer operators.

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.

Using consumer electronic devices to estimate whole-body vibration exposure

The cost and complexity of commercially available devices for measuring whole-body vibration is a barrier to the systematic collection of the information required to manage this hazard at workplaces. The potential for a consumer electronic device to be used to estimate whole-body vibration was assessed by use of an accelerometer calibrator, and by collecting 42 simultaneous pairs of measurements from a fifth-generation iPod Touch and one of two gold standard vibration measurement devices (Svantech SV111 [Svantech, Warsaw, Poland] or Brüel & Kjær 4447 [Brüel & Kjær Sound & Vibration Measurement A/S, Nærum, Denmark]) while driving light vehicles on a variety of different roadway surfaces. While sampling rate limitations make the accelerometer data collected from the iPod Touch unsuitable for frequency analysis, the vibration amplitudes recorded are sufficiently accurate (errors less than 0.1 m/s(2)) to assist workplaces manage whole-body vibration exposures.

Personal consequences of work-related physical discomfort: an exploratory study

BACKGROUND

Work-related physical discomfort has been reported in Australian optometrists. The purpose of this paper is to explore the personal consequences of work-related discomfort.

METHODS

Forty-seven optometrists with self-reported work-related discomfort participated in a 30-minute telephone or face-to-face interview related to ergonomics and physical comfort. Self-employed, employee, locum and retired optometrists participated. Four avenues were investigated; namely, description of discomfort, non-work contributing factors, whether the participant has ever stopped work due to discomfort, and the treatments accessed to alleviate discomfort. These data were subject to qualitative and quantitative analyses.

RESULTS

Reported discomfort ranged from mild to severe. Eight participants (17 per cent) ascribed their discomfort entirely to work and seven (15 per cent) cited non-work factors as the cause. Many participants (32, 68 per cent) reported that non-work factors, for example, sport and driving, aggravated existing work-related discomfort and for some, their discomfort impacted on home and leisure activities. There were 15 participants (32 per cent), who have stopped work because of discomfort, including two who have ceased working as an optometrist and two who now work reduced hours. The majority (32) continue to work despite discomfort. Many participants (31, 66 per cent) seek treatment to alleviate discomfort, with seven participants (15 per cent) reporting that they receive multiple therapies per week. Work-related discomfort was generally viewed as a personal issue, with most participants accessing treatment in their own time (27, 57 per cent) and funding it personally or with private health insurance. Only four participants have received funding through workers' compensation or income protection insurance.

CONCLUSIONS

Work-related discomfort has significant financial and personal costs for some Australian optometrists. These qualitative data can be used to develop quantitative tools for assessing the impact of discomfort on quality of life for optometrists and their families. The results also highlight the need for preventative action to reduce work-related discomfort within the optometric profession.

The perceived importance and the presence of creative potential in the health professional's work environment

The value of creative employees to an organisation's growth and innovative development, productivity, quality and sustainability is well established. This study examined the perceived relationship between creativity and work environment factors of 361 practicing health professionals, and whether these factors were present (realised) in their work environment. Job design (challenges, team work, task rotation, autonomy) and leadership (coaching supervisor, time for thinking, creative goals, recognition and incentives for creative ideas and results) were perceived as the most important factors for stimulating creativity. There was room for improvement of these in the work environment. Many aspects of the physical work environment were less important. Public health sector employers and organisations should adopt sustainable strategies which target the important work environment factors to support employee creativity and so enhance service quality, productivity, performance and growth. Implications of the results for ergonomists and workplace managers are discussed with a participatory ergonomics approach recommended.

PRACTITIONER SUMMARY

Creative employees are important to an organisation's innovation, productivity and sustainability. The survey identified health professionals perceive a need to improve job design and leadership factors at work to enhance and support employee creativity. There are implications for organisations and ergonomists to investigate the creative potential of work environments.

Effect of control order on steering a simulated underground coal shuttle car

Most terrestrial vehicles are steered via a first-order control for vehicle heading, such as a conventional steering wheel. A joystick which provides second-order control of vehicle heading is used to steer some underground coal shuttle cars. A desktop virtual simulation of the situation was employed to compare the steering accuracy of 24 novice participants randomly assigned to either first-order or second-order joystick steering conditions. The average steering accuracy of participants assigned to the first-order joystick condition was superior, however there was considerable individual variability and some participants assigned to the second-order steering condition were able to perform the task equally and successfully. Desktop virtual simulation may be a useful component of training and competency assessment for operators of these vehicles.

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.

The contributions of human factors and ergonomics to a sustainable minerals industry

This article describes examples of the application of human factors research and development work to a sustainable minerals industry. It begins by outlining human-related aspects of the minerals industry and the key human factors work previously undertaken in this domain. The focus then switches to sustainability in the minerals industry. Sustainability principles are introduced and illustrations provided of how human factors research and development work fits within such a framework. Three case studies of human factors in the minerals industry research are presented and the sustainability implications in each case study are highlighted. Finally, future trends related to human factors work in a sustainable minerals industry are addressed, in particular the opportunities and possible adverse consequences that increasing deployment of mining automation might bring.

PRACTITIONER SUMMARY

Minerals industries are a major global activity with significant sustainability implications. Aspects of sustainability in mining are examined using three case studies. These illustrate the contribution of human factors/ergonomics in reducing risks; developing emergency response management systems; and the value of participatory ergonomics in improving the design of mining equipment.

Directional control-response compatibility of joystick steered shuttle cars

Shuttle cars are an unusual class of vehicle operated in underground coal mines, sometimes in close proximity to pedestrians and steering errors may have very serious consequences. A directional control-response incompatibility has previously been described in shuttle cars which are controlled using a steering wheel oriented perpendicular to the direction of travel. Some other shuttle car operators are seated perpendicular to the direction of travel and steer the car via a seat mounted joystick. A virtual simulation was utilised to determine whether the steering arrangement in these vehicles maintains directional control-response compatibility. Twenty-four participants were randomly assigned to either a condition corresponding to this design (consistent direction), or a condition in which the directional steering response was reversed while driving in-bye (visual field compatible). Significantly less accurate steering performance was exhibited by the consistent direction group during the in-bye trials only. Shuttle cars which provide the joystick steering mechanism described here require operators to accommodate alternating compatible and incompatible directional control-response relationships with each change of car direction.

PRACTITIONER SUMMARY

A virtual simulation of an underground coal shuttle car demonstrates that the design incorporates a directional control-response incompatibility when driving the vehicle in one direction. This design increases the probability of operator error, with potential adverse safety and productivity consequences.

Construct validation of a physical model colonoscopy simulator

BACKGROUND

Previous studies have demonstrated the construct validity of virtual reality colonoscopy simulators by showing that they can distinguish between users according to their level of endoscopic experience. Although physical model simulators are known to simulate looping more realistically than these devices, they lack published validation evidence.

OBJECTIVE

To assess the construct validity of a physical model simulator, the Kyoto Kagaku Colonoscope Training Model (Kyoto Kagaku Co. Ltd, Kyoto, Japan) and to determine its suitability for assessing the insertion skill of trainee colonoscopists.

DESIGN

Validation study; 21 experienced colonoscopists and 18 novices made 2 attempts at each of 4 standard cases on the Kyoto Kagaku physical model simulator, and we compared their performance on each case.

SETTING

A medical simulation center in a large tertiary hospital.

MAIN OUTCOME MEASUREMENTS

Completion rates, times to cecum, and peak forces applied to the colon model.

RESULTS

Compared with novices, experienced colonoscopists had significantly higher completion to cecum rates and shorter times to cecum for each of the 4 cases (all P < .005). For 2 cases, experienced colonoscopists also exerted significantly lower peak forces than did novices (both P = .01).

LIMITATIONS

Two of the model's 6 "standard cases" were not included in the study.

CONCLUSIONS

The 4 cases included in the study have construct validity in that they can distinguish between the performance of experienced colonoscopists and novices, reproducing experienced/novice differences found in real colonoscopy. These cases can be used to validly assess the insertion skill of colonoscopy trainees.

Assessing the realism of colonoscopy simulation: the development of an instrument and systematic comparison of 4 simulators

BACKGROUND

No useful comparative data exist on the relative realism of commercially available devices for simulating colonoscopy.

OBJECTIVES

To develop an instrument for quantifying realism and provide the first wide-ranging empiric comparison.

DESIGN

Repeated measures, observational study. Nineteen experienced colonoscopists completed cases on 4 colonoscopy simulators (AccuTouch, GI Mentor II, Koken, and Kyoto Kagaku) and evaluated each device.

SETTING

A medical simulation center in a large tertiary hospital.

MAIN OUTCOME MEASURES

For each device, colonoscopists completed the newly developed Colonoscopy Simulator Realism Questionnaire (CSRQ), which contains 58 items grouped into 10 subscales measuring the realism of different aspects of the simulation. Subscale scores are weighted and combined into an aggregated score, and there is also a single overall realism item.

RESULTS

Overall, current colonoscopy simulators were rated as only moderately realistic compared with real human colonoscopy (mean aggregated score, 56.28/100; range, 48.39-60.45, where 0 = "extremely unrealistic" and 100 = "extremely realistic"). On both overall realism measures, the GI Mentor II was rated significantly less realistic than the AccuTouch, Kyoto Kagaku, and Koken (P < .001). There were also significant differences between simulators on 9 subscales, and the pattern of results varied between subscales.

LIMITATIONS

The study was limited to commercially available simulators, excluding ex-vivo models. The CSRQ does not assess simulated therapeutic procedures.

CONCLUSIONS

The CSRQ is a useful instrument for quantifying simulator realism. There is no clear "first choice" simulator among those assessed. Each has unique strengths and weaknesses, reflected in the differing results observed across 9 subscales. These findings may facilitate the targeted selection of simulators for various aspects of colonoscopy training.

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 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.

Evidence-based guidelines for the wise use of computers by children: physical development guidelines

Computer use by children is common and there is concern over the potential impact of this exposure on child physical development. Recently principles for child-specific evidence-based guidelines for wise use of computers have been published and these included one concerning the facilitation of appropriate physical development. This paper reviews the evidence and presents detailed guidelines for this principle. The guidelines include encouraging a mix of sedentary and whole body movement tasks, encouraging reasonable postures during computing tasks through workstation, chair, desk, display and input device selection and adjustment and special issues regarding notebook computer use and carriage, computing skills and responding to discomfort. The evidence limitations highlight opportunities for future research. The guidelines themselves can inform parents and teachers, equipment designers and suppliers and form the basis of content for teaching children the wise use of computers. STATEMENT OF RELEVANCE: Many children use computers and computer-use habits formed in childhood may track into adulthood. Therefore child-computer interaction needs to be carefully managed. These guidelines inform those responsible for children to assist in the wise use of computers.

The influence of desk and display design on posture and muscle activity variability whilst performing information technology tasks

Desk design and computer display height can affect posture and muscle activation during computer use. Amplitudes of postural variables and muscle activity during computer use do not explain the results from epidemiological studies of musculoskeletal discomfort and disorders related to computer use. The purpose of this study was to assess variability of posture and muscle activity during work with two computer display heights and book/paper, in conjunction with a curved desk designed to provide forearm support and a traditional, straight desk. 18 male and 18 female participants performed 10-min tasks involving keying, mousing, reading and writing in six desk/display conditions. 3D posture and surface emg were assessed for the final 2 min of each task. The curved desk resulted in greater postural and muscle activity variation, suggesting an advantage of this supportive surface over the straight desk. There was little difference in variability associated with the two display heights. However, greater variability of posture and muscle activity was evident with the book/paper condition. Non-touch typists had greater neck flexion variation. The design of information technology tasks and workstations can influence the short term variation in posture and muscle activity. Variation is influenced independently of mean postures and muscle amplitudes and therefore needs to be considered to adequately assess the risk of musculoskeletal disorders.

Effect of visual display height on modelled upper and lower cervical gravitational moment, muscle capacity and relative strain

Head and neck posture is an important factor in neck pain related to computer use; however, the evidence for an optimal posture is unconvincing. This study measured the 3-D postures of 36 young adults during use of three different display heights. Cervical extensor muscle strain was estimated using modelled gravitational load moments and muscle capacities. The influence of more or less upper vs. lower cervical movement was also explored across a broad range of potential postures. Overall cervical extensor muscle capacity diminished away from a neutral posture whilst gravity moment increased with flexion. Overall cervical extensor muscle strain increased with head flexion but remained stable into head extension. Individual differences in the amount of upper and lower cervical movement had an important effect on strain, particularly for some muscles. Computer display height guidelines are an important component of ergonomics practice, yet the relative strain on neck extensor muscles as a function of display height has not been examined. The current findings provide more detailed biomechanical evidence that ergonomists can incorporate with usability and other evidence to determine appropriate display height recommendations.

The impact of computer display height and desk design on muscle activity during information technology work by young adults

Computer display height and desk design are believed to be important workstation features and are included in international standards and guidelines. However, the evidence base for these guidelines is lacking a comparison of neck/shoulder muscle activity during computer and paper tasks and whether forearm support can be provided by desk design. This study measured the spinal and upper limb muscle activity in 36 young adults whilst they worked in different computer display, book and desk conditions. Display height affected spinal muscle activity with paper tasks resulting in greater mean spinal and upper limb muscle activity. A curved desk resulted in increased proximal muscle activity. There was no substantial interaction between display and desk.

A comparison of posture and muscle activity during tablet computer, desktop computer and paper use by young children

Computers are now widely used by children. Tablet computers are becoming widely available and promoted for use by school children. The primary objective of this study was to compare the posture and muscle activity of children using a tablet computer to the posture and muscle activity of children using a desktop computer and paper technology. Eighteen children (mean age 5.6 years) performed a colouring-in task in tablet, desktop and paper conditions. 3-D posture and muscle activity around the neck and shoulder was assessed. Tablet computer use was similar to paper use, with less neutral spinal posture, more elevated scapular posture and greater upper trapezius and cervical erector spinae activity. This was offset by greater variability of posture and muscle activity. Tablet computer use clearly results in different musculoskeletal stresses than desktop computer use. Computer use guidelines need to be appropriate to traditional and emerging technologies. Tablet computers are being promoted for use by adults and children. However, the physical impact of using this type of technology is not known. The findings of this study provide the first tablet-specific evidence to inform guidelines on wise use of tablet computers by children.

The impact of computer display height and desk design on 3D posture during information technology work by young adults

Computer display height and desk design to allow forearm support are two critical design features of workstations for information technology tasks. However there is currently no 3D description of head and neck posture with different computer display heights and no direct comparison to paper based information technology tasks. There is also inconsistent evidence on the effect of forearm support on posture and no evidence on whether these features interact. This study compared the 3D head, neck and upper limb postures of 18 male and 18 female young adults whilst working with different display and desk design conditions. There was no substantial interaction between display height and desk design. Lower display heights increased head and neck flexion with more spinal asymmetry when working with paper. The curved desk, designed to provide forearm support, increased scapula elevation/protraction and shoulder flexion/abduction.

Children's posture and muscle activity at different computer display heights and during paper information technology use

OBJECTIVE

The 3-D posture and muscle activity in the neck and upper limb were assessed in children using high-, mid-, and book-level displays, which correspond to working conditions frequently observed when children interact with computers or books and paper.

BACKGROUND

The 3-D posture and muscle activity of children reading and inputting data with computers and paper had not been previously assessed.

METHODS

Twenty-four children aged 10 to 12 years and of normal height performed an interactive task involving reading from a book and writing on paper or reading from a computer display and inputting data using a mouse and keyboard.

RESULTS

Head and neck flexion increased as the visual target was lowered. The high display resulted in mainly upper cervical relative extension, and the book display resulted in both upper and lower cervical flexion. The book condition resulted in greater cervical erector spinae and upper trapezius activity than did the mid and high conditions.

CONCLUSION

The data suggest that a mid-level display may be more appropriate for children than a high display (e.g., when the display is placed on top of the central processing unit). The mid display also results in a more upright and symmetrical posture and lower mean muscle activity than does working with books and paper flat on the desk.

APPLICATION

This study provides short-term laboratory study evidence for the formulation of guidelines for workstation design and adjustment for children. Use of computers by children is increasing, yet ergonomic guidelines lag behind those for adults.

Reliability of the JobFit System Pre-Employment Functional Assessment Tool

Functional capacity testing in the pre-employment or post-offer phase of recruitment is increasing in popularity as a preventative tool for controlling sprains and strains in the workplace. The purpose of this study is to determine the reliability of the JobFit System Pre-Employment Functional Assessment (PEFA) as a whole, or in parts, as a precursor for a validity study investigating the relationship between PEFA results and workplace injury rates and severity. A group of 28 healthy male coal mine employees were videotaped whilst they participated in a generic JobFit System Pre-Employment Functional Assessment (PEFA) including tests of aerobic physical fitness, balance, postural tolerances and material handling tolerances. Twenty participants performed a second trial. The test component scores and overall PEFA scores were compared between trials (test-retest, intra-rater) and assessors (inter-rater) to determine their reliability expressed in terms of ICC. Using an ICC score of > 0.75 as good and > 0.90 as excellent, in conjunction with percentage agreement a good to excellent reliability rating was allocated to the overall PEFA score, floor to bench lift, bench to overhead lift, bilateral carry and climbing. A moderate to good rating was recorded for bench to shoulder lifts, reaching forward, reaching overhead and stooping. A poor to moderate rating was recorded for squatting, balance and fitness tests. Test-retest scores were typically lower than intra-tester and inter-tester scores. ICC scores should be interpreted with consideration of their limitations and in conjunction with the actual test results.

The effect of forearm support on musculoskeletal discomfort during call centre work

Using a computer keyboard with the forearms unsupported has been proposed as a causal factor for neck/shoulder and arm/hand diagnoses. Recent laboratory and field studies have demonstrated that forearm support might be preferable to working in the traditional "floating" posture. The aim of this study was to determine whether providing forearm support when using a normal computer workstation would decrease musculoskeletal discomfort in intensive computer users in a call centre. A randomised controlled study (n = 59), of 6 weeks duration was conducted. Thirty participants (Group 1) were allocated to forearm support using the desk surface with the remainder (Group 2) acting as a control group. At 6 weeks, the control group was also set up with forearm support. Both groups were then monitored for another 6 weeks. Questionnaires were used at 1, 6 and 12 weeks to obtain information about discomfort, workstation setup, working posture and comfort. Nine participants (Group 1 n = 6, Group 2 n = 3) withdrew within a week of commencing forearm support either due to discomfort or difficulty in maintaining the posture. At 6 weeks, the group using forearm support generated significantly fewer reports of discomfort in the neck and back, although the difference between the groups was not statistically significant. At 12 weeks, there were fewer reports of neck, back and wrist discomfort when preintervention discomfort was compared with post intervention discomfort. These findings indicate that for the majority of users, forearm support may be preferable to the "floating" posture implicit in current guidelines for computer workstation setup.

The effect of upper extremity support on upper extremity posture and muscle activity during keyboard use

Forearm support during keyboard use has been reported to reduce neck and shoulder muscle activity and discomfort. However, the effect of forearm support on wrist posture has not been examined. The aim of this study was to examine the effect of 3 different postures during keyboard use: forearm support, wrist support and "floating". The floating posture (no support) was used as the reference condition. A wrist rest was present in all test conditions. Thirteen participants completed 20 min wordprocessing tasks in each of the test conditions. Electromyography was used to monitor neck, shoulder and forearm muscle activity. Bilateral and overhead video cameras recorded left and right wrist extension, shoulder and elbow flexion and radial and ulnar deviation. The forearm support condition resulted in significantly less ulnar deviation (p < or = 0.007), less time spent in extreme ulnar deviation (p = 0.002) and less reports of discomfort than the "floating" condition (p = 0.002). The wrist support but not the forearm support condition resulted in less trapezius and anterior deltoid muscular activity (p < 0.007). These findings indicate that typing with upper extremity support in conjunction with a wrist rest may be preferable to the "floating" posture implicit in current guidelines.

A randomized and controlled trial of a participative ergonomics intervention to reduce injuries associated with manual tasks: physical risk and legislative compliance

A participative ergonomics approach to reducing injuries associated with manual tasks is widely promoted; however only limited evidence from uncontrolled trials has been available to support the efficacy of such an approach. This paper reports on a randomized and controlled trial of PErforM, a participative ergonomics intervention designed to reduce the risks of injury associated with manual tasks. One hundred and seventeen small to medium sized food, construction, and health workplaces were audited by government inspectors using a manual tasks risk assessment tool (ManTRA). Forty-eight volunteer workplaces were then randomly assigned to Experimental and Control groups with the Experimental group receiving the PErforM program. Inspectors audited the workplaces again, 9 months following the intervention. The results showed a significant decrease in estimates of manual task risk and suggested better legal compliance in the Experimental group.

Spontaneous transitions in the coordination of a whole body task

This paper describes an example of spontaneous transitions between qualitatively different coordination patterns during a cyclic lifting and lowering task. Eleven participants performed 12 trials of repetitive lifting and lowering in a ramp protocol in which the height of the lower shelf was raised or lowered 1 cm per cycle between 10 and 50 cm. Two distinct patterns of coordination were evident: a squat technique in which moderate range of hip, knee and ankle movement was utilised and ankle plantar-flexion occurred simultaneously with knee and hip extension; and a stoop technique in which the range of knee movement was reduced and knee and hip extension was accompanied by simultaneous ankle dorsi-flexion. Abrupt transitions from stoop to squat techniques were observed during descending trials, and from squat to stoop during ascending trials. Indications of hysteresis was observed in that transitions were more frequently observed during descending trials, and the average shelf height at the transition was 5 cm higher during ascending trials. The transitions may be a consequence of a trade-off between the biomechanical advantages of each technique and the influence of the lift height on this trade-off.

Kinaesthetic judgements and refinement of striking action

Little is known about the developmental course of striking action. This cross-sectional study explored the refinement of striking in 28 children aged between 4 and 12 years and investigated how well they could use kinaesthesis to gauge the length of an unseen bat. The kinematic data (including smoothness of movement) showed quantitative differences between the age groups. In contrast, no differences were found in the children's ability to judge the length of the unseen bat: within three strikes all of the children had made a clean hit, indicating that they had successfully judged bat length. The children then appeared to memorize the bat with which they had accurately hit the target and made: (1) minimal errors when using this bat in later trials and (2) predictable errors when using two other bats of different sizes. The results show that the striking action becomes optimized over childhood, with smoothness of movement providing an index of this refinement. The findings also suggest that young children have a higher level of kinaesthetic sensitivity than has been assumed previously on the basis of static limb positioning tasks. The results suggest that the striking task used in this study might be a useful tool for investigating the development of movement skills in children with developmental disorders.

Visual display height

We examined the influence of backrest inclination and vergence demand on the posture and gaze angle that workers adopt to view visual targets placed in different vertical locations. In the study, 12 participants viewed a small video monitor placed in 7 locations around a 0.65-m radius arc (from 65 degrees below to 30 degrees above horizontal eye height). Trunk posture was manipulated by changing the backrest inclination of an adjustable chair. Vergence demand was manipulated by using ophthalmic lenses and prisms to mimic the visual consequences of varying target distance. Changes in vertical target location caused large changes in atlanto-occipital posture and gaze angle. Cervical posture was altered to a lesser extent by changes in vertical target location. Participants compensated for changes in backrest inclination by changing cervical posture, though they did not significantly alter atlanto-occipital posture and gaze angle. The posture adopted to view any target represents a compromise between visual and musculoskeletal demands. These results provide support for the argument that the optimal location of visual targets is at least 15 degrees below horizontal eye level. Actual or potential applications of this work include the layout of computer workstations and the viewing of displays from a seated posture.

Wrist posture during computer pointing device use

OBJECTIVE

This research examines individual differences in the wrist postures adopted during the use of two pointing devices (mouse and trackball).

DESIGN

A multiple case study of twelve participants was employed.

BACKGROUND

The use of pointing devices may lead to musculoskeletal discomfort and injury as a consequence of prolonged exposure to postures involving wrist extension and ulnar deviation.

METHODS

Wrist flexion/extension and radial/ulnar deviation was measured while twelve participants completed two standardised tasks involving horizontal and vertical cursor movements respectively.

RESULTS

Exposure to extreme ulnar deviation and wrist extension was observed in the use of computer mouse and trackball. The trackball involved decreased ulnar deviation and increased wrist extension, however considerable individual differences were observed.

CONCLUSIONS

Some users may be placed at risk of injury by prolonged exposure to the use of such devices, while others may not. A trackball may reduce the exposure to extreme ulnar deviation, but in some cases, a trackball may increase exposure to extreme wrist extension.