Figure 19.3 Gait phases in normal level walking with typical horizontal (F) and vertical force (FV) components and their ratio, F/F, for one

Consequently, if the sizes of the horizontal and vertical force components applied to the ground during walking and the coefficient of friction for the actual tribosystem are known, then it is possible to evaluate whether this system is potentially slippery and hazardous (Figure 19.4). A transverse force component has been ignored here (level walking assumed), but should be added to these equations in slip situations where the transverse component plays a role.