Effects of vehicle bumper height and impact velocity on type of lower extremity injury in vehicle-pedestrian accidents

In nonfatal passenger vehicle-pedestrian accidents, the lower extremities are the most commonly injured body parts. The European Enhanced Vehicle-safety Committee Working Group 17 (EEVC/WG17) pedestrian subsystem test method using a legform impactor has been developed mainly for evaluation of aggressiveness of the front bumper of passenger vehicles. However, in recent years the number of sports utility vehicles (SUV) with a high bumper has been rapidly increasing. Since the bumper height is different between a passenger vehicle and an SUV, the type of lower extremity injury may be different. The type of lower extremity injury caused by this different bumper height should be clarified, because the test method and vehicle safety countermeasure must take into account a certain type of injury. Furthermore, the effect of vehicle impact velocity on the type of lower extremity injury in vehicle-pedestrian accidents has not been investigated so far. Therefore, the objective of this study is to clarify the effect of vehicle bumper height and vehicle impact velocity on the type of lower extremity injury in vehicle-pedestrian accidents. The Pedestrian Crash Data Study (PCDS), an in-depth accident database in the USA, was used for the current analyses. The results indicate that the type of injury, i.e., to the tibia and knee ligament, could become an injury to the femur with an increase in bumper height. Furthermore, the main injury at an impact velocity of around 20-30 km/h is to the knee ligament. On the other hand, the main injury at an impact velocity of around 40 km/h is a fracture of the lower extremities.