Slipping and falling
Dr Jean Luc Chaverot, Maryse Garceau, CTC
Slipping represents a serious risk in the world of work and forms part of the mandatory requirements placed on safety footwear. It is also important with regard to city and leisure footwear, including trainers, intended for general day-to-day use. The anti-slip requirements for these types of footwear should therefore also be understood and assessed. In France, the permanent survey of day-to-day accidents (EPAC) estimated that almost 11% of the population had a day-to-day accident of some sort in 2017. Furthermore, almost 50% of accidents involve falling due to slipping. It is in fact the most frequent domestic accident.
These accidents are often considered to be harmless. However, they can cause very serious injury, ranging from permanent disability to even death. The parts of the body mainly affected by a fall are firstly, the lower limbs (feet, tibia, femur, etc.) followed by the upper limbs (hands, elbows, wrists) due to the person's inability to fall safely. These accidents especially concern children and the elderly. In the case of children under the age of 15, accidents occur in the same place regardless of gender. They mostly have accidents at home (48%) and in public places (39%), half of which occur in sports and play areas. Falling is, by far, the most frequent type of accident (60%). Among the elderly, almost a third of whom have a fall every year from the age of 65, it has a psychological as well as a medical impact.
In 2019, slipping and falling (16.3%) was the second greatest workplace risk (causing an interruption in employment for more than three days), after manual handling operations, which were the cause of 50% of accidents. Slipping and falling (15% of accidents) also represents the second cause of accidents on the journey between home and work (the first cause being the loss of control of a mode of transport (58%). Regardless of environmental conditions at the time of an accident (ground is slippery, obstructed, in poor condition or variation in the height of steps), falling due to slipping remains one of the main causes.
A risk to be mastered
Falling is caused by a slip that cannot be controlled by the person involved who then loses their balance. Anybody who has to walk about is concerned about slipping. It is indissociable from locomotion as soon as two surfaces come into contact. Slipping is attributable to:
• A lack of grip between the sole and the ground,
• Environmental factors such as uneven surfaces, moisture and the presence of slippery elements,
• Human factors specific to each person.
As mentioned earlier, the risk of falling due to slipping is not limited to the workplace. To prevent these risks, city and leisure footwear must provide a level of grip that meets the needs of users as closely as possible. The sole, particularly the choice of soling material and the geometry of its tread pattern, plays a vital role in ensuring grip. To prevent a fall, a sole’s resistance to slipping has to be determined and the coefficient of friction between interacting surfaces is an important factor for predicting slip resistance during walking. To prevent a fall, two conditions have to be met:
• Restrict the initial slipping of the foot (static),
• Limit the speed of slipping so as not to lose the balance (dynamic).
NF EN ISO 24267
CTC, drawing on its know-how, offers various laboratory tests to assess the slipping of city and athleisure footwear. In order to respond to this problem and ensure the safety of users, standard NF EN ISO 24267 (November 2020) determines a test method. It applies to all types of footwear (casual, sports, high heels, sandals, etc.), outsoles, top pieces and sole material, except for PPE footwear and special purpose footwear containing spikes, metal studs or similar elements.
To simulate user conditions, forward-moving tests on a flat surface and forward-moving heel tests are carried out on a wet ceramic floor. Top pieces with or without a pivot are tested in the forward-moving heel position only. In order to characterise a material prior to moulding, it is also possible to carry out forward-moving tests on a flat surface on plates of material. To respond to this problem and prevent these risks, a number of European brands and specifiers have already decided to incorporate this standard and these tests into their product specifications.
Testing a complete shoe for resistance to slipping.
Credit: CTC
