2014-03-01 12:00 - Messages

Safety in machinery design and construction

Performance for substantive safety outcomes
This paper presents the findings of qualitative research which examined how manufacturers addressed safety matters in the course of designing and constructing machinery, and the factors shaping their responses. This topic was investigated in 66 Australian firms that supplied machinery into local and international markets. Based on in-depth interviews, observation of machinery and review of documentation, firm performance was evaluated for three substantive safety outcomes - hazard recognition (types and instances), risk control measures (type and quality) and provision of safety information (scope and quality). The paper discusses differences in firm performance for these outcomes and concludes that there is a need for greater and more effective attention to safety in machinery design and construction, in order to advance the goal of preventing death, injury and illness arising from machinery.

Source: Bluff E. Safety Sci. 2014; 66: 27-35.
http://dx.doi.org/10.1016/j.ssci.2014.02.005

On the use of low-cost radar networks for collision warning systems aboard dumpers

The use of dumpers is one of the main causes of accidents in construction sites, many of them with fatal consequences. These kinds of work machines have many blind angles that complicate the driving task due to their large size and volume. To guarantee safety conditions is necessary to use automatic aid systems that can detect and locate the different objects and people in a work area. One promising solution is a radar network based on low-cost radar transceivers aboard the dumper. The complete system is specified to operate with a very low false alarm rate to avoid unnecessary stops of the dumper that reduce its productivity. The main sources of false alarm are the heavy ground clutter, and the interferences between the radars of the network. This article analyses the clutter for LFM signaling and proposes the use of Offset Linear Frequency Modulated Continuous Wave (OLFM-CW) as radar signal. This kind of waveform can be optimized to reject clutter and self-interferences. Jointly, a data fusion chain could be used to reduce the false alarm rate of the complete radar network. A real experiment is shown to demonstrate the feasibility of the proposed system.

Source: González-Partida JT, León-Infante F, Blázquez-García R, Burgos-García M. Sensors (Basel). 2014; 14(3): 3921-3938.
http://dx.doi.org/10.3390/s140303921

The effect of instructions on potential slide-out failures during portable extension ladder angular positioning

Accidents involving portable ladders are a common cause of serious occupational and non-occupational injuries throughout the industrialized world. Many of these injuries could be prevented with better instruction on the proper usage of portable ladders. Research is reported that focused on both the human factors and engineering aspects of portable extension ladder usage based on common ladder setup procedures. Results of the human factors experiment revealed evidence of unsafe acts that could lead to catastrophic ladder slide-out accidents in real-life situations. Six different ladder setup methods were evaluated for safety and stability based on placement angles: the basic, 75 degree, stand-reach, L sticker, 4:1, and bubble level methods. Ideally, ladder users would set the ladder up at 75.5 degrees to achieve the consensus industry standard safest angle. Setup methods varied in complexity and nature of instruction. The level method produced the most accurate and the least variable results. The engineering analysis determined the coefficient of friction of a variety of clean and contaminated surfaces commonly used with ladders. This analysis determined the total number of slide-out failures that would likely have occurred in the data obtained in each of the ladder setup methods tested in the human factors experiment. Based on test participants' setup angles, the average calculated ladder slide-out failure rate was 8.7 percent for ladders positioned on a surface with the lowest measured coefficient of friction. When broken down by ladder setup method, the 4:1 method had a failure rate of 18.8 percent, the 75 degree method had a failure rate of 15.2 percent, and the basic method had a failure rate of 9.8 percent. The stand-reach and L sticker methods had identical failure rates at 3.3 percent and the level method was best at 1.1 percent. The level method provided the lowest error, least variability, and setup closest to the target angle of 75.5 degrees. Analysis of the overall results revealed the need for additional user training and clearer instructions affixed to ladders. This research is unique in that it combines an analysis and comparison of human factors and engineering in the same study.

Source: Campbell AO, Pagano CC. Accid. Anal. Prev. 2014; 67C: 30-39.
http://dx.doi.org/10.1016/j.aap.2014.01.025

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