Wrap Around Distance WAD of Pedestrian and Bicyclists and Relevance as Influence Parameter for Head Injuries 2015-01-1461
During most pedestrian-vehicle crashes the car front impacts the pedestrian and the whole body wraps around the front shape of the car. This influences the head impact on the vehicle. Meanwhile the windscreen is a major impact point and tested in NCAP conditions. The severity of injuries is influenced by car impact speed; type of vehicle; stiffness and shape of the vehicle; nature of the front (such as the bumper height, bonnet height and length, windscreen frame); age and body height of the pedestrian; and standing position of the pedestrian relative to the vehicle front. The so called Wrap Around Distance WAD is one of the important measurements for the assessment of protection of pedestrians and of bicyclists as well because the kinematic of bicyclists is similar to that of pedestrians.
For this study accidents of GIDAS were used to identify the importance of WAD for the resulting head injury severity of pedestrians and bicyclists. GIDAS (German In-Depth-Accident-Study) collects accidents as representative sample of the German accident situation based on in-depth-investigation. A total number of n=548 pedestrian and n=436 bicyclists suffered a head impact with the car collected within n=27,666 accidents with all kind of traffic participants and injured persons from the years 1999 to 2013 which are used for the study.
Results: A significant influence respectively an increase of WAD by the driving speed of the bicycle cannot be found. The cumulative frequencies show, that WAD 1500 only covers about 8% of bicyclists but 18% of pedestrians. WAD 2100 covers about 51% of bicyclists and 74% of pedestrians. The WAD for pedestrian as measure of distance from the ground to the impact point of the head is dependent on the impact speed of the car. For lower speeds the front hood area is more often contacted and for higher speeds the windscreen. For Vans and off-road cars front hood impacts can only be seen in lower speed collisions. The WAD of bicyclists in general is higher than for pedestrians. The cumulative frequencies of body heights show that bicyclists are larger than pedestrians. The injury severity of the head (AIS head) is increasing with the age of the pedestrian or bicyclist. Only 6.9% of pedestrians and 3.3% of bicyclists in the age group of 16 to 25 years suffer head injuries of AIS 3+, in the age group over 55 years there are 19.7% of pedestrians and 16.1% of bicyclists.
The WAD is not a significant influence parameter for the injury severity of the head. The WAD is only increasing slightly with higher injury severity of the head (AIS head). The WAD is a usable parameter for the correlating impact speed of the car. Age and impact speed of the car have highly significant influence (p<0.001) and body height has slightly significant influence on the injury severity of the head (p<0.05).