Slip Potential for Commonly Used Inclined Grated Metal Walkways

Abstract

OCCUPATIONAL APPLICATIONS Grated walkway materials are used to discourage accumulation of debris in environments where spillage is likely. Several types of grated walkway materials exist and the choice of walkway material impacts the likelihood of a slip event. In this research, the normalized coefficients of friction were examined for three commonly used grated metal walkways at 0°, 5°, 10°, 15°, and 20°, during both contaminated and dry conditions, and for uphill and downhill walking. Slips were found to occur at inclines as low as 10° from the horizontal, with a high proportion of slips occurring at 20° in the contaminated conditions. The fewest slips occurred during trials for the diamond weave grating. As such, the authors suggest that this grating is preferable for preventing slips, compared to serrated bar or perforated gratings similar to those examined here. TECHNICAL ABSTRACT Background: No specific guidelines or regulations are provided by the Mine Safety and Health Administration for the use of inclined grated metal walkways in mining plants. Mining and other companies may be using walkway materials that do not provide sufficient friction, contributing to slip and fall injuries. Purpose: The purpose of this study was to determine if there are significant differences in the required friction for different grated metal walkways during walking in diverse conditions. Methods: The normalized coefficients of friction were measured for 12 participants while walking up and down an instrumented walkway with different inclinations (0°, 5°, 10°, 15°, and 20°) and with and without the presence of a contaminant (glycerol). Self-reported slip events were recorded and the required coefficients of friction were calculated considering only the anterior/posterior components of the shear forces. Additionally, the available coefficients of friction for these walkway materials were measured at the 0° orientation using a tribometer, with and without the presence of the contaminant, using a boot heel as well as Neolite as the test feet. Results: The number of slips increased when the inclination angle reached 10° and above. Of all materials tested, the diamond weave grating was found to have the best performance at all inclines and when contaminated or dry. A high number of slips occurred for the perforated grating and serrated bar grating at 20° when contaminated. Conclusions: Results of this study suggest that the diamond weave grating provides significantly better friction compared to serrated bar and perforated gratings, especially at inclines greater than 10°.