The Mechanics of a Pedestrian Run Over by A Motor Vehicle

In road accidents, there are frequently incidents in which a person is hit by a vehicle and then run over or people who are lying on the road who are run over (without prior collision). Chest injuries are the most severe injuries, especially intrathoracic organ injuries; these are caused by a wheel rolling over the body. For the safety development of cars, these events are very rare (< 0.1 %) and therefore do not require mandatory measures. However, these incidents are often processed with forensic expertise. In this respect, knowledge of kinematics, mechanics and injury analysis are important. In 1975, the author wrote a diploma thesis that deals with the detailed technical mechanism of running over a person lying on the road; this work has not been published to date. Nevertheless, there have been repeated individual enquiries prompting the need for publication at the present time. The body of the pedestrian must be seen in mechanical strength as a rectangular compressible body with varying stiffness and flexible body segments. Characteristic end positions and distance-time correlations were found in the tests when the vehicle was run over at speeds of 30 and 50 kph. The most important influencing factor can be considered to be the crossing point on the body. The maximum movement of the body in driving direction of the wheel occurred when the thorax was run over and was significantly greater compared to when the head was run over; it was also greater with a braking wheel than with an unbraked wheel.