The objective of this study is to establish criteria for head impact protection to be required for optimal performance of motorcycle helmets. Head injury severity sustained in real accidents was compared with test results obtained by laboratory drop tests according to ECE-R 22, considering residual damage of protective padding as an indicator for head impact loading. 15 integral helmets were collected from real motorcycle crashes providing basic important accident data concerning head injury and head impact characteristics. For new helmets similar to those used in the real accident sample, comparable damage was simulated in laboratory drop tests using various anvils and impact areas and applying step by step increasing impact velocities. The following principal results and conclusions were obtained: (1) Increasing head injury severity is not closely related to increasing residual deformation of the energy absorbing liner; (2) Critical head injury (Abbreviated Injury Scale 5) may occur for impacts which are related to rather low translational head deceleration of approximately 150 g or lower measured in the ECE-R 22 headform. High rotational acceleration might be decisive in these particular accident cases; and (3) test results suggest that ECE-R 22 limits should be significantly reduced to optimize head impact protection.
Abstract