Repeatability and bias of two walkway safety tribometers

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Repeatability and bias of two walkway safety tribometers

Powers, C.M. / Kulig, K. / Flynn, J. / Brault, J.R.

Slipping is one of the most common causes of falls and has been reported to account for approximately 62 % of underfoot accidents in the workplace. Injuries sustained from falls are projected to cost 85.4 Mrd USD in 2020 annually. To measure friction between the floor and the shoe, various types of tribometers and ASTM standards have been developed to assess walkway slip-resistance with the goal of improving pedestrian safety. The purpose of this study was to determine the repeatability and bias of the PIAST and VIT tribometers under both dry and wet conditions. Both devices were tested on an AMTI force platform over a wide range of angles. Bias was assessed by comparing the tribometer slip resistance reading to the actual F_x/F_z ratio measured by the force plate, while reliability was established by evaluating the ability of the tribometers to reproduce F_x, F_z, and the F_x/F_z ratio. Both tribometers demonstrated high degrees of bias and repeatability under both wet and dry conditions; however, each measured different slip-resistance values for the same surface. Further study should be directed at establishing which tribometer best simulates initial foot contact during gait with respect to measuring slip resistance.