Abstract
The goal of the study was to conduct a preliminary analysis of the kinematics of tram-pedestrian collision in case of a side impact. A T6A5-type tram (ČKD Tatra, Prague, Czech Republic), typical for Prague public transport, was used for the crash analysis and reconstruction of the collision.
The tram was travelling at the speed of 10 km/h. The pedestrian response to the side impact was analysed using a crash-test dummy The Hybrid III 50th Percentile Male Pedestrian Dummy (JASTI, Tokyo, Japan).
The motion capture camera system and high-speed cameras recorded the kinematics of collision. For the purpose of this study, the postimpact dummy movement was approximated by the motion of its centre of mass (COM).
The analysis was only focused on the translation movement of the COM in the frontal plane of dummy (along the horizontal and vertical axes). The calculation of coefficient of restitution and percentage loss of kinetic energy during the impact phase assumed a simple inelastic collision and the conservation of linear momentum.
The results showed a significant change of coefficient of restitution immediately after the initial impact. At first, the coefficient of restitution was high (e = 0.94), suggesting an almost perfectly elastic collision, followed by a sharp decrease (e = 0.07) within a short period of time (t = 0.02 s) that suggested an almost perfectly inelastic collision.
After that, the coefficient of restitution reached a plateau phase with the values ranging from 0.18 to 0.32, which corresponded to a percentage loss of kinetic energy falling within 89% and 97% during the collision. The preliminary analysis of this case study highlighted some of the features of side-impact tram-pedestrian collision and its kinematics.
The study outcomes could be an important step towards understanding and improving the reconstruction of such traffic accidents, as well as assisting in the future design and development of novel technologies to improve the pedestrian safety.