The Dutch Ministry of Infrastructure and Environment asked TNO to perform a study to obtain, on short term, a first insight on the required level of headprotection for speed-pedelec riders. TNO performed a simulation study using available human models in the software package MADYMO. In this study the falling behaviour in single sided accidents of speed-pedelec riders, was compared to that of moped drivers and cyclists. It is believed that a speed- pedelec helmet should be able to give appropriate protection against head injury for single sided accidents. Three common types of single sided two-wheeler-accident configurations have been selected and simulated. Further, a small set of variations of the conditions (operational velocity, friction of the ground, cause of the fall) have been taken into account. The falling mechanism as well as a selected set of head injury causation parameters were investigated and related to the helmet test parameters. The conclusions of this study are as follows: * In general higher initial velocities mainly result in higher head impact velocities and consequently a higher head impact level. Whether this high impact level is reached depends on the actual falling mechanism. In case the impact-energy of the fall is absorbed by the head first, high impact levels are reached. If the fall is broken, for example by other body parts touching the ground first or by hooking of the body to the frame of the bicycle, the impact level will not reach the high impact levels. More simulations and parameter variations are needed to come up with quantitative conclusions on the impact levels. Based on the results of this study, TNO advices to base the required head protection level on the high impact levels, so where the fall of the head is not broken, in order to protect speed-pedelec riders well. Since the operational speed of speed-pedelec ridersis higher than that of the cyclists, they need a higher level of protection. More research is needed to quantify the actual protection level. * A large variety in head impact locations is observed, ranging from the face, to top and side of the head. The variety is in line with the results of the study of the GDV [8] where the head impact locations of cyclists were studied. Further, it is known that the side of the head around the ears is more fragile than the front or top of the head [9] as the skull is less thick at that location. Based on these results, TNO advises to also protect the speed-pedelec riders head around the ears. * No clear pattern could be found in the head movements after impact. Different movements are observed, ranging from full sliding, rotating, bouncing and combinations thereof. Therefore, TNO advises a helmet surface that could deal with sliding, rotating and bouncing, requiring a smooth surface with holes for ventilation that will not cause hooking into. (Author/publisher)
Samenvatting