Citation

Strandberg L, Lanshammar H. J. Occup. Accid. 1981; 3(3): 153-162.

Copyright

(Copyright © 1981, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

Official statistics indicate that slipping is one of the most common causes of accidents. Falls contribute to about 40% of the 4000 fatal accidents that occur annually in Sweden. In fact, falls are more common than motor vehicles as a registered cause of accidental deaths. During 1975 occupational injuries caused approximately 3 million sickness-days and 26% of them were due to falling accidents. The actual involvement of skidding cannot be evaluated, because slip-ups have been registered only as a subgroup of "falls on the same level". However, skidding may initiate other types of accidents as well. This is supported by preliminary data from a new occupational injury information system. The computer based system allows selective retrievals. In one of the first outputs slip-ups are involved in at least 25 accidents out of 102 including "fall to a lower level" during house construction work. Thus it is urgently necessary to improve the slipping resistance of shoes, floors and walking surfaces. Development is guided by friction measurement with different kinds of apparatus. Unfortunately, many of these are based on an oversimplified theory of static friction, which seems to be quite irrelevant due to the viscoelastic properties of shoe soles and heels. However, even if the apparatus measures dynamic friction, tests must be performed with forces and motions closely resembling a real human skid. Otherwise, friction measurements and real slipping resistance will be poorly correlated.Recently, a gait analysis system was developed which now has been used to evaluate force and motion data from walking and skidding subjects in the laboratory. The system includes piezoelectric and optoelectronic sensors connected on-line to a computer with substantial software for gait analysis. This paper presents the method and results such as: the average critical slip motion started 0.05 s after heel strike. At this point the vertical load was about 60% of body weight and acting at the heel rear edge, the experiments usually resulting in a fall if the sliding exceeded 0.5 m s-1 in velocity or 0.1 m in distance.