The research project „bicycle helmet“, which was funded by the German Insurers Accident Research (UDV) and lasted three years had the aim to develop recommendations for improved test methods for bicycle helmets, based on detailed analysis of real world accidents and combined biomechanical considerations. The data base consisted of 117 well documented and retrospectively recorded fatal bicycle accidents from the safety accident database (SUD) of the Institute of Legal Medicine, Munich and 500 prospectively recorded accidents with minorly to severely injured cyclists from the University Hospital of Münster and 71 prospectively recorded accidents with minorly to severely injured cyclists from the University Hospital of Munich. By analyzing this data two typical accident scenarios were identified: the single-vehicle accident of the bicycle rider and the collision with the front part of a car. The most common situation of the single-vehicle accident is falling sideways at rather low speed and by falling off the bicycle forward over the handlebar. Regarding the accidents with a car, the bicycle rider typically collides with the front part of the car approximately under a right angle. The typical collision speeds are around 15 kph and 40 kph. Then, selected typical accident scenarios were reconstructed, supplemented with generic scenarios and simulated in two steps. In the first step, the kinematics of the bicycle rider, especially the parameters of the head contact on the road surface or the car were developed. In the second step (finite element simulation), the risks for selected head injuries were determined using the head model of the University of Strasbourg (SUFEHM). In addition, the benefit of a bicycle helmet has been shown in these head impact scenarios using a detailed finite element model of a bicycle helmet which was developed within this project. By analyzing the real-world accidents it became clear that bicycle helmets, which only meet the minimum requirements of the European standard EN 1078, still offer potential for optimization. For severely injured bicycle riders head impact points were derived from the location of soft tissue injury on the skull and face which are often found in the temporal region and the lower part of the forehead. Some of these areas are not covered by existing testing procedures. Therefore, extending the test area should be considered. The test speed in current test methods appears to be sufficient regarding single-vehicle accidents. In a severe collision with a car, far higher head impact speeds can occur. Therefore, it seems to be sensible to include higher testing speeds for the shock absorption test in future testing methods to be even better protected in such accident scenarios. However, tightening the requirements of the test standard must be weighed against such factors like helmet weight and helmet ventilation, which may have an impact on the acceptance of bicycle helmets. (Author/publisher)
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