Integrated pedestrian countermeasures – Potential of head injury reduction combining passive and active countermeasures

A rapid development of both pedestrian passive and active safety, such as pedestrian bonnets/airbags and autonomous braking, is in progress. The aim of this study was to investigate the potential pedestrian head injury reduction from hypothetical passive and active countermeasures compared to an integrated system. The German In-Depth Accident Study (GIDAS) database was queried from 1999 to 2008 for severely (AIS3+) head injured pedestrians when struck by car or van fronts. This, resulted in 54 cases where information was sufficient. The passive countermeasure was designed to mitigate head injuries caused by the bonnet area, A-pillars, and the remaining windscreen area up to 2.1 m wrap around distance (WAD). The active countermeasure was an autonomous braking system, which was activated one second prior to impact if the pedestrian was visible to a forward-looking sensor. The integrated system was a direct combination of the passive and active countermeasures. Case by case the effect from each of the active, passive and integrated systems was estimated. For the integrated system, the influence of the active system on the passive system performance was explicitly modeled in each case. The integrated system resulted in 50% (95% confidence interval: 30–70%) greater effectiveness than the active countermeasure in reducing the number of pedestrians sustaining severe (AIS3+) head injuries, and 90% (95% CI: 50–150%) greater effectiveness than the passive countermeasure. Integrated systems of passive and active pedestrian countermeasures offer a considerably increased potential for head injury reduction compared to either of the two systems alone.

► Potential of integrated pedestrian protection systems (compared to active and passive systems). ► Based on accident data, AIS3+ head injuries. ► Passive safety; deployable bonnet and windscreen airbag. ► Active safety; autonomous braking.