Although the focus in the field of vulnerable road user safety has been on pedestrian safety so far, accident data shows a high relevance for cyclist-passenger car collisions as well. On the basis of an extensive simulation study the accident kinematics of cyclists is investigated for different vehicle classes in order to assess the effectiveness of existing passive safety measures, such as an active bonnet, a pedestrian or an extended cyclist windscreen airbag. Furthermore, the benefit of a reduced impact speed is analyzed in order to also consider the potential of autonomous emergency brake systems.

The assessment is done with the help of a specially developed procedure, which allows a vehicle-specific effectiveness measurement of passive and active safety measures for both pedestrians and cyclists. Six representative vehicle front geometries and four cyclist heights are considered within the kinematics analysis, reaching from a 6-year-old child to a 95%-male. Each cyclist model consists of a size-specific bicycle model and the corresponding MADYMO Ellipsoid Pedestrian Model placed on top. The simulation models and parameters are validated by reconstruction of a real accident taken from the GIDAS database. Two representative lateral accident constellations are defined together with four pedal positions. The speed of the cyclist always amounts to 15 km/h. The pedestrian kinematics analysis is based on simulations with comparable impact constellations as well as equal vehicle speeds.

An in-depth analysis shows that further rearwards located head impact positions constitute a fundamental characteristic of cyclist-passenger car frontal collisions compared to pedestrian frontal collisions. This is confirmed by the simulation results, where the cyclist head impact positions can reach up to the roof leading edge and in case of sports cars even beyond. Furthermore, the simulations show high values for head impact velocity as well as angle. The cyclist head impact velocities usually lie above the collision speed, which limits the benefit of purely design-related measures.

In order to study the cyclist accident kinematics in a lateral impact under real test conditions, full scale tests with a Polar-II dummy positioned on a moving bicycle (15 km/h) are conducted with different vehicle speeds (40, 30 & 20 km/h). Overall, the tests show a good correlation with the simulations and illustrate the safety potential of a collision speed reduction. Conspicuous are the loads measured for the secondary head impact, which are much higher compared to the primary impact, even for low vehicle speeds.

The results obtained from the assessment procedure reveal that cyclists are often not addressed by an active bonnet, whereas an additional airbag is able to reduce the head injury risk significantly. But it has to cover the whole A-pillar in order to be really effective. A reduction of impact speed is most beneficial - this is equally valid for all vehicle front categories, both for cyclists and for pedestrians as well as for adults and children. Additionally, there is a positive effect on the secondary impact.