Relationship between impact velocity and injuries in fatal pedestrian-car collisions.

The most common type of fatal pedestrian-car collision, i.e. a passenger car with a wedge or pontoon shaped front striking an erect adult with this front, was investigated. A reliable calculation of the impact velocity range by a technical expert and a comprehensive autopsy suitable for traffic accidents were performed in every case. A total of 47 fatalities form the material of this study and the impact velocities varied between 18 and 142 km/h. Primary and secondary injuries did not show a relationship to impact velocity. The occurrence of four types of indirect injuries revealed a clear relationship to impact velocity, i.e. spinal fractures, ruptures of the thoracic aorta, inguinal skin ruptures and dismemberment of the body. Important parameters such as the type of car, impact velocity range and indirect injuries are listed for each individual case. Because of the limited number of cases, the impact velocity ranges (3-30 km/h) instead of mean values were considered. A cautious interpretation of the data can be summarised in the following conclusions: If there is no spinal fracture, the velocity was below 70 km/h and probably below 50 km/h. Aortic and inguinal skin ruptures are always present if the velocity was above 100 km/h but never occurred below 50-60 km/h. If dismemberment occurs, the velocity was above 90 km/h. Consequently, an estimation of the impact velocity from the presence or absence of indirect injuries is possible in pedestrian-car collisions of the type examined. However, the selection criteria applied in this study and additional parameters influencing the collision dynamics have to be considered carefully.