Factors influencing the slip index measurements with the Horizontal Pull Slipmeter

Several factors that might influence the outcomes of the slip index measurements with the Horizontal Pull Slipmeter were examined. These factors were either those not clearly specified in the operating guidelines of the device or those clearly specified but with a high variability in operator compliance. The results indicated that the shoe pad thickness, sanding, alignment between the string and the force gauge, and temperature were the factors that led to significant differences at the levels evaluated. The differences due to string stiffness, string length, duration from cleaning to friction measurement, dwell time, battery level and relative humidity did not reach a statistically significant level. Extra guidelines are needed for those factors that could result in significant variations in order to lead to more consistent results.