In order to decrease head injuries to pedestrians and other vulnerable road users, a pop-up hood, also called Active Hood, was developed and is presently in production. The focus of development has been on the HIC criterion and skull fractures. However, several studies have shown that brain injury is also common, in all types of traffic injuries.

The aim of this study was to investigate the influence of the gap between the car hood and underlying hard structures on brain injuries. Free-flying head component tests and full-scale dummy tests were performed. Linear and rotational head acceleration was measured and the Wayne State University Head Injury Model (WSUHIM) was used to calculate the risk of brain injury.

A 100 mm gap considerably reduced head rotational acceleration compared to smaller under-hood distances. It also reduced strain in the WSUHIM model. This study indicated that the Active Hood provides an adequate counter-measure to both skull fractures and brain injuries.