Measuring the Slip Resistance of Winter Footwear

Slip and fall accidents represent an enormous burden in terms of human suffering and economic costs. In winter conditions, outdoor falls increase as cold temperatures and precipitation create hazardous conditions underfoot. An effective method of reducing falls is the use of slip resistant footwear. However, the optimization of this footwear is hindered by the fact that slip resistance is not easily measured and the validity of existing measurement devices is questionable. The series of four studies presented here show the progression of work utilizing human-centred approaches to evaluating the performance of winter footwear on real winter surfaces and have led to the development of a new test method. To start, traditional measures of slip severity were used to evaluate the effectiveness of winter boots and cleated footwear devices while subjects walked in common winter conditions. Walking trials on level and uneven icy surfaces showed that while cleated footwear did reduce slip frequency, they did not prevent dangerous slips from occurring. Further testing showed that the current standard test conditions and parameters used for determining footwear slip resistance do not adequately simulate gait in winter conditions. As a result, a new usercentred protocol was developed for testing footwear. Subjects were asked to stand and walk across a wet, icy surface that was tilted progressively until they could no longer maintain balance, thereby establishing the maximum achievable incline angle for a variety of styles of footwear. This method proved to be reliable on wet ice so a refined protocol was applied to a larger sample of footwear which was then tested on dry ice as well as snow conditions. The results showed the importance of testing winter footwear in snow conditions, which had not been done before. These studies demonstrate the viability of testing footwear without removing the critically important human component.