2013-05-01 12:00 - Messages

Biomechanical characteristics of slipping during unconstrained walking, turning, gait initiation and termination

Slipping biomechanics was investigated on both non-contaminated and oil-contaminated surfaces during unconstrained straight-line walking ('walking'), turning, gait initiation and termination. In walking, backward slipping was more frequent, whereas forward slipping was more frequent when turning. Stopping and gait initiation engendered only forward and backward slipping, respectively. Based on slip distance and sliding velocity, severity of forward slipping was least in walking than for the other gait tasks, whereas the tasks had similar effects on backward slipping. Relative to the dry surface, heel and foot contact angles reduced and heel contact (HC) velocity increased for all gait tasks on the contaminated surface. Ground reaction forces were generally lower on the contaminated surface, suggesting kinetic adaptation immediately following HC. Required coefficient of friction (RCoF) did not correlate with slip distance suggesting that RCoF may not be a useful kinetic parameter for assessing slipping risk on contaminated surfaces. Practitioner Summary: Slipping is hazardous in everyday locomotion and occupational settings. This study investigated foot control kinematics and kinetics across various gait tasks on both a non-contaminated and an oil-contaminated walking surface. Turning, gait termination and gait initiation were associated with a greater risk of slip-related falls than unconstrained walking.

Source : Nagano H, Sparrow WA, Begg RK. Ergonomics 2013; ePub. http://dx.doi.org/10.1080/00140139.2013.787122

 

Better retention of skill operating a simulated hydraulic excavator after part-task than after whole-task training

OBJECTIVE: We examined whether part-task training produces better learning and retention than whole-task training of a trench-and-load task performed on a hydraulic excavator simulator. BACKGROUND: For complex perceptual-motor tasks that involve several components and require spatial awareness of the environment, part-task training will be effective if the benefit of being able to focus attention on each component outweighs the cost of integrating the components. We predicted that such would be the case for learning to operate an excavator. METHOD: A part-task training group practiced separate Carrier Positioning, Trenching, and Truck Loading modules, whereas a whole-task training group practiced the Trench and Load module, which combines elements from the other modules. The latter module, involving different scenarios, was performed by both groups immediately after training and following a 2-week retention interval. RESULTS: Production rate on the trench-and-load task was better overall on the retention test than on the immediate test. The part-task group showed improvement on the retention test compared with the immediate test, whereas the whole-task group did not. The part-task group showed higher productivity rates than did the whole-task group on the retention test. CONCLUSION: Part-task training on the excavator simulator results in better skill retention than does whole-task training. The benefit of part-task training is likely to be found for other tasks requiring control of implements in various environments. APPLICATION: Part-task training can result in better retention of complex perceptual-motor skills involving several components, even when immediate transfer to the whole task does not show better performance than whole-task training.

Source : So JC, Proctor RW, Dunston PS, Wang X. Hum. Factors 2013; 55(2): 449-460. http://dx.doi.org/10.1177/0018720812454292

Best Practice Guidelines for the Safe Use of Elevating Work Platforms in the Horticultural Industry

Horticultural mobile elevating work platforms (H/MEWP) are complex pieces of equipment that are used in hazardous conditions. As the current state of knowledge
has changed around the use of this equipment these best practice guidelines are an update of the 2003 version. Since 2004, 17 serious harm accidents involving H/MEWPs have been reported to MBIE. Nine of these accidents involved tip-overs of the H/MEWP and two serious harm injuries occurred when operators fell from the work platform. In two separate accidents the operator suffered an electric shock when the H/MEWP touched power lines. In three serious harm injuries operators suffered amputations after becoming entangled in the moving parts of an H/MEWP. Additionally, two serious harm accidents occurred when orchard workers were run over by moving H/MEWPs.
These guidelines provide guidance on safe work practices for the use and maintenance of H/MEWPs in the horticultural industry and are supplementary to other guidance on working at heights and the use of elevating work platforms. These are industry-specific best practice guidelines which are intended to cover only the following industry activities:

  • horticulture
  • arboriculture
  • horticulture plant and machinery
  • hirehorticultural contractors
  • agriculture
  • nurseries, parks and reserves.

Source : http://www.osh.govt.nz/order/catalogue/pdf/platforms-hort.pdf

 

Mobile elevated work platform (MEWP) incident analysis - RR961

Mobile Elevated Work Platforms (MEWPs) are commonly used across all industrial sectors by a whole variety of trades, including mechanical and electrical contractors, and painters and decorators, as a safe, temporary method of working at height. There is a large range of MEWPs on the market and their controls and functionality varies depending on the category, manufacturer, model and size of machine. As their popularity and range of applications has grown, concerns have emerged about trapping/crushing accidents involving MEWPs. This report identifies accidents involving MEWPs and analyses common factors found. The work has focused on MEWP occupants being trapped against overhead or adjacent objects whilst in the platform of the MEWP, particularly when the operator becomes trapped over the controls (sustained involuntary operation of control). Typically, this has occurred when the operator has been moving the MEWP within relatively confined areas. This research has centred on person-machine interface/human factors analysis rather than engineering issues.

Source : http://www.hse.gov.uk/research/rrpdf/rr961.pdf

 

Mobile elevated work platforms (MEWPs): Phase 3 - RR960

HSE has carried out a programme of research projects focused on MEWPs, in order to provide a better understanding of some of the issues involved and to help work towards their improved and safer design and operation. An initial phase of work, reported in HSE Research Report RR961, examined the human factors involved in such accidents as a means of identifying possible solutions. The subsequent phase of work (to be published later in 2013) went on to critically evaluate MEWP control interfaces and platform environments. The work detailed in this current report is the third phase of MEWPs research and has aimed to capture MEWP end users knowledge in relation to the key risk factors for entrapment/crushing whilst operating MEWPS, using insights gained from their experiences of near misses/incidents. Suggestions for how these might be addressed are also considered.

Source : http://www.hse.gov.uk/research/rrpdf/rr960.pdf

A ‘normal accident’ with a tower crane? An accident analysis conducted by the Dutch Safety Board

Since cranes and tower cranes are complex installations they constitute critical aspects of safety at construction sites. The risks posed by cranes are specific and should be treated as such. Prior to assessing the impact of management and organizational factors, accident analysis should first start with an analysis of the actual accident process. The Dutch Safety Board conducted such an accident analysis involving a non-mobile, peak less, trolley tower crane. This tower crane collapsed at a Rotterdam building site on July 10th 2008. The results show that the flexibility of the configuration of the mast and the horizontal arm of the crane or the jib was greater than that calculated by the design engineer. While hoisting a heavy load, the crane collapsed. The defects in the design of the crane were not identified, so the accident was classified as a ‘normal accident’, one that was essentially integral to the design and could also thus occur in other tower cranes of the same make. Such tower crane design shortcomings emerge as process disturbances once the crane is operational. Despite its shortcomings, the collapsed crane did have a CE mark. Other officially required safety audits and crane inspections did not address possible defects in the design, production, or operation of the crane. Once on the market there appears to be no further effective safety net for the detection of structural weaknesses. The article will also discuss the role of parties involved in construction and inspection of tower cranes.

Source : Paul Swuste, A ‘normal accident’ with a tower crane? An accident analysis conducted by the Dutch Safety Board, Safety Science, Volume 57, August 2013, Pages 276-282, ISSN 0925-7535, 10.1016/j.ssci.2013.03.002.
http://www.sciencedirect.com/science/article/pii/S0925753513000647

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