LED Area Lighting to Reduce Glare for Roof Bolter Operators.

Researchers from the National Institute for Occupational Safety and Health (NIOSH) developed a light-emitting diode (LED) area luminaire called the Saturn and conducted a laboratory study using a Fletcher High Dual-boom Mast Feed (HDDR) roof bolting machine. The Saturn luminaire was designed to (1) enhance floor illumination to enable better detection of trip hazards in the interior spaces of a roof bolter and (2) reduce glare that has typically been an issue of concern on roof bolters. This paper reports on the results of achieving the second objective. The existing roof bolter lighting was the baseline and was compared with three versions of the Saturn luminaire relative to light intensity (100%, 75%, and 50%). Discomfort and disability glare data were obtained from 30 participants that comprised three age groups. Discomfort glare perceptions were obtained using the De Boer rating scale, and disability glare was quantified by using Mars Letter Contrast Sensitivity tests. Discomfort glare was reduced at least 3 levels with all Saturn versions. Also, a predictive model was used to estimate discomfort glare, and the results were similar. Disability glare was the least for the Saturn's 50% intensity, and all Saturn versions had significantly less disability glare than with the baseline lighting. Veiling luminance was calculated and used as another indicator of disability glare. Veiling luminance was 28 to 42 times greater with the baseline lighting as compared with that of the Saturn lighting. Lastly, visibility levels were calculated. The Saturn versions were 4 to 6.5 times better in terms of visibility level.

Investigation of Machine-Mounted Area Lighting to Reduce Risk of Injury from Slips-Trips-Falls for Operators of Mobile Surface Mining Equipment.

Nonfatal injuries from slips, trips, and falls (STF) that occur at surface mines can result from inadequate lighting. Mobile equipment operators are among the occupations associated with the nonfatal incidents reported to the U.S. Mine Safety and Health Administration (MSHA). In addition, getting on/off the equipment (ingress/egress) frequently adds to the highest proportion of nonfatal incidents. Accordingly, researchers at the Pittsburgh Mining Research Division (PMRD), National Institute for Occupational Safety and Health (NIOSH) conducted a field study to investigate lighting on haul trucks and wheel loaders with regard to glare and illuminance levels recommended by the Illuminating Engineering Society (IES). The objective was to determine whether two light-emitting diode (LED) area luminaires-a Mr. Beams® (model MB390 Ultrabright) (area luminaire-1) and a NIOSH-developed Saturn (custom-designed for a mine roof bolter study) (area luminaire-2)-could complement a headlamp luminaire. Measured levels of visual tasks, with the headlamp alone and the area luminaires plus the headlamp, demonstrated that illuminance met or exceeded IES-recommended levels. Nevertheless, the area luminaires illuminated a much broader area, which is key to increasing hazard awareness. Discomfort and disability glare were lower with area luminaire-1 than with area luminaire-2. Differences in glare were more noticeable for newer models of haul trucks and loaders featuring updated ingress/egress system designs. This study demonstrates that commercially available luminaires, such as area luminaire-1, are capable of complementing headlamp lighting, and can thus improve a miner's ability to detect and avoid STF hazards.

Investigation of human body vibration exposures on haul trucks operating at U.S. surface mines/quarries relative to haul truck activity.

Workers who operate mine haul trucks are exposed to whole-body vibration (WBV) on a routine basis. Researchers from the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Mining Research Division (PMRD) investigated WBV and hand-arm vibration (HAV) exposures for mine/quarry haul truck drivers in relation to the haul truck activities of dumping, loading, and traveling with and without a load. The findings show that WBV measures in weighted root-mean-square accelerations (aw) and vibration dose value (VDV), when compared to the ISO/ANSI and European Directive 2002/44/EC standards, were mostly below the Exposure Action Value (EAV) identified by the health guidance caution zone (HGCZ). Nevertheless, instances were recorded where the Exposure Limit Value (ELV) was exceeded by more than 500 to 600 percent for VDVx and awx, respectively. Researchers determined that these excessive levels occurred during the traveling empty activity, when the haul truck descended down grade into the pit loading area, sliding at times, on a wet and slippery road surface caused by rain and overwatering. WBV levels (not normalized to an 8-h shift) for the four haul truck activities showed mean awz levels for five of the seven drivers exceeding the ISO/ANSI EAV by 9-53 percent for the traveling empty activity. Mean awx and awz levels were generally higher for traveling empty and traveling loaded and lower for loading/dumping activities. HAV for measures taken on the steering wheel and shifter were all below the HGCZ which indicates that HAV is not an issue for these drivers/operators when handling steering and shifting control devices.

Development of ergonomics audits for bagging, haul truck and maintenance and repair operations in mining.

The development and testing of ergonomics and safety audits for small and bulk bag filling, haul truck and maintenance and repair operations in coal preparation and mineral processing plants found at surface mine sites is described. The content for the audits was derived from diverse sources of information on ergonomics and safety deficiencies including: analysis of injury, illness and fatality data and reports; task analysis; empirical laboratory studies of particular tasks; field studies and observations at mine sites; and maintenance records. These diverse sources of information were utilised to establish construct validity of the modular audits that were developed for use by mine safety personnel. User and interrater reliability testing was carried out prior to finalising the audits. The audits can be implemented using downloadable paper versions or with a free mobile NIOSH-developed Android application called ErgoMine. Practitioner Summary: The methodology used to develop ergonomics audits for three types of mining operations is described. Various sources of audit content are compared and contrasted to serve as a guide for developing ergonomics audits for other occupational contexts.

The effect of vibration exposure during haul truck operation on grip strength, touch sensation, and balance.

Falls from mobile equipment are reported at surface mine quarry operations each year in considerable numbers. Research shows that a preponderance of falls occur while getting on/off mobile equipment. Contributing factors to the risk of falls include the usage of ladders, exiting onto a slippery surface, and foot or hand slippage. Balance issues may also contribute to fall risks for mobile equipment operators who are exposed to whole-body vibration (WBV). For this reason, the National Institute for Occupational Safety and Health, Office of Mine Safety and Health Research conducted a study at four participating mine sites with seven haul truck operators. The purpose was to ascertain whether WBV and hand-arm vibration (HAV) exposures for quarry haul truck operators were linked to short-term decreases in performance in relation to postural stability, touch sensation threshold, and grip strength that are of crucial importance when getting on/off the trucks. WBV measures of frequency-weighted RMS accelerations (wRMS) and vibration dose value (VDV), when compared to the ISO/ANSI standards, were mostly below levels identified for the Health Guidance Caution Zone (HGCZ), although there were instances where the levels were within and above the specified Exposure Action Value. Comparably, all mean HAV levels, when compared to the ISO/ANSI standards, were below the HGCZ. For the existing conditions and equipment, no significant correlation could be identified between the WBV, HAV, postural stability, touch sensation threshold, and grip strength measures taken during this study.

Assessment of whole-body vibration exposures and influencing factors for quarry haul truck drivers and loader operators.

To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines.

Pressure distribution on the anatomic landmarks of the knee and the effect of kneepads.

This study examines stress transmitted to anatomic landmarks of the knee (patella, combined patella tendon and tibial tubercle) while in static kneeling postures without kneepads and while wearing two kneepads commonly worn in the mining industry. Ten subjects (7 male, 3 female) simulated postures utilized in low-seam mines: kneeling in full flexion; kneeling at 90° of knee flexion; and kneeling on one knee while in one of three kneepad states (no kneepads, non-articulated kneepads, and articulated kneepads). For each posture, peak and mean pressure on the anatomic landmarks of the knee were obtained. The majority of the pressure was found to be transmitted to the knee via the combined patellar tendon and tibial tubercle rather than through the patella. While the kneepads tested decreased the maximum pressure experienced at the combined patellar tendon and tibial tubercle, peak pressures of greater than 25 psi were still experienced over structures commonly injured in mining (e.g. bursa sac - bursitis/Miner's Knee). The major conclusion of this study is that novel kneepad designs that redistribute the stresses at the knee across a greater surface area and to other regions of the leg away from key structures of the knee are needed.