Development of a simulation system for performing in situ surface tests to assess the potential severity of head impacts from alleged childhood short falls.

There is considerable debate in the medical literature surrounding the issue of fatal child head injuries being caused by short falls. When reviewing a case history a medical expert will form an opinion of the likely cause of an injury based on his/her knowledge of the literature, training and experience of similar cases. The severity of an injury is determined by the age of the victim, fall height, body impact site and the impact surface. A medical expert, when forming an opinion, is invariably assisted by a description of the scene or scene photographs and assumes the mechanical response of the floor conforms in the same way to "similar" surfaces. The impact response characteristics of the entire surface mixture is critically important when considering the potential for head injury to a child due to a short fall. However, at present during an investigation, the response of a surface to a head impact remains an unknown, since a simple description of, or cursory glance at, a floor surface is insufficient in determining its potential to cause injury. This paper documents the development of a simulation system for assessing the impact response, and potential to cause injury, of domestic floor surfaces during short falls. The method utilises a headform and drop tower adapted from techniques and current standards used to assess the potential for childhood head injuries of playground surfaces and pedestrian-bonnet impacts. The results suggest that the potential of a surface to cause head injury is dependent on the entire surface mixture, including the top surface layer (e.g. carpet and underlay), the underlying surface (wood, chipboard or concrete) and the support material (joists, supports. etc.). The results illustrate a wide range of injury potential between surface mixtures. The simulation system shows the potential to discriminate between differences in surface mixture. In conclusion, the authors suggest that in future investigations, the response of the entire surface mixture be taken into account when forming an opinion on the injury potential of short falls.