In China, nearly 25% of traffic fatalities are pedestrians. To avoid those fatalities in the future, rapid development of countermeasures within both passive and active safety is under way, one of which is autonomous braking to avoid pedestrian crashes. The objective of this work was to describe typical accident scenarios for pedestrian accidents in China. In-depth accident analysis was conducted to support development of test procedures for assessing Autonomous Emergency Braking (AEB) systems. Beyond that, this study also aims for estimating the mitigation of potential crash severity by AEB systems.
The China In-depth Accident Study (CIDAS) database was searched from 2011 to 2014 for pedestrian accidents. A total of 358 pedestrian accidents were collected from the on-site in-depth investigation in the first phase of CIDAS project (2011-2014). The number of car/SUV/VAN/microbus to pedestrian (all called hereafter referred to as car-to-pedestrian accidents in this study) cases is n=265, which accounts for 74% of all collected pedestrian accidents. Statistics on all collected pedestrian crashes provided an overview understanding of the pedestrian safety situation in China. To achieve the goal of the study, 255 car-to-pedestrian cases were analyzed to figure out the most frequently scenarios, which can be the reference to set the AEB test procedure in China. Furthermore, 183car-to-pedestrian cases, with detailed information regarding accident vehicles, pedestrians and environment, were reconstructed using PC-Crash.
A hypothetical autonomous braking system would activate when the pedestrian successfully detected by the sensing system and then new impact speeds will be calculated. The study documents that the most frequent situations in China are:(1) Unobscured, pedestrian walks out from nearside; (2) Unobscured, pedestrian walks from far side; (3) pedestrian walking along the road. More than 20% accidents could be avoided with an AEB system (with an instant deceleration −8.0m/s2) functioned at 1.0 second prior to crash. The mean of new impact speed for un-avoided cases decreased to 24km/h from 39km/h in real accidents.