The effect of anti-slip devices on pedestrian safety : method development and practical test

Sammanfattning: Every winter, more than 100,000 pedestrians in the Nordic countries receive medical treatment as a result of falls on slippery surfaces. In addition, the risk of injury reduces interest in outdoor activities during the wintertime. Pedestrians injured in single-pedestrian accidents on icy and snowy surfaces also experience more serious injuries than pedestrians injured on other surfaces. Thus, there is a clear need for measures to reduce single-pedestrian injuries and improve the safety of walking, without curtailing the activity, year round. A "slip accident" occurs when a person loses his/her balance. An attempt is normally made to recover one's balance, and the person's balance is either recovered or a fall occurs. An injury may be the consequence of such a fall. The most critical phases of the human gait are the heel strike and the toe-off.Various countermeasures can be used .to reduce the risk of a person slipping and sliding when walking outdoors during the wintertime. Such countermeasures may involve the use of individual equipment, services provided by the community to assist vulnerable road-user groups or the public at large, and policy changes in winter-maintenance practices. Examples of measures targeting individuals include information on the risk of slipperiness, and encouraging the use of (or providing) winter footwear and/or anti-slip devices to be fastened to shoes. The issues considered in this thesis are related to the prevention of injuries from single-pedestrian accidents by a specific measure, the use of anti-slip devices. More specifically, the following questions have been addressed in the studies it is based upon:How can the properties of anti-slip devices be assessed?How can more effective anti-slip devices be developed?Do anti-slip devices improve walking ability and safety?In laboratory investigations, test methods were developed and applied to 33 anti-slip devices to assess the test methods against validated criteria, and to analyse the benefits of using different types of anti-slip devices. The tests were conducted by observing people making standard movements on various surfaces chosen to simulate the variations in winter maintenance standards on walkways: snow on ice, sand on ice, gravel on ice, salt on ice and pure ice. Movements were analysed from observations of video recordings, and subjective rating scales were developed to assess walking safety and walking balance. In addition, in a field study questionnaires were used to record exposure, occurrence of slips/falls, descriptions of the slips/falls that occurred and general experiences of the use of anti-slip devices.The results show that it is possible to record the performance of anti-slip devices for pedestrians in a laboratory setting, and that the method developed for doing this is satisfactory. The methods used, together with friction measurements made by the Finnish Institute of Occupational Health (FIOH), may provide a sound basis for establishing standard methodology for testing anti-slip devices as personal protective equipment.The results from the Laboratory tests can be used to identify favourable designs of anti-slip devices, and indicate that whole-foot devices are the best type, followed by heel devices, for supporting a natural gait. The results from the Field study show that the availability and use of anti-slip devices can promote walking, which is beneficial from a health perspective, and it does not lead to an increased risk of slipping/falling even though it increases exposure. Overall, the results indicate that the use of anti-slip devices is an effective traffic safety countermeasure for reducing single-pedestrian accidents.Aspects that warrant further attention include verification of the effects of anti-slip devices on exposure and the occurrence of falls, and their effects in relation to specific groups such as elderly.