Evaluation of an autonomous braking system in real-world PTW crashes
2014-06-12T09:16:46Z (GMT) by
Objectives: Powered 2-wheelers (PTWs) are becoming increasingly popular in Europe. They have the ability to get around trafﬁc queues, thus lowering fuel consumption and increasing mobility. The risk of rider injury in a trafﬁc crash is however much higher than that associated with car users. The European project, Powered Two Wheeler Integrated Safety (PISa), identiﬁed an autonomous braking system (AB) as a priority to reduce the injury consequences of a PTW crash. The aim of this study was to assess the potential effectiveness of the AB system developed in PISa, taking into account the speciﬁc system characteristics that emerged during the design, development and testing phases. Methods: Fifty-eight PTW cases representing European crash conﬁgurations were examined, in which 43 percent of riders sustained a Maximum Abbreviated Injury Scale (MAIS) 2+ injury. Two of the most common crash types were a PTW impacting a stationary object (car following scenario) 16% and an object pulling across the PTW path (crossing scenario) 54%. An expert team analysed the in-depth material of the sample crashes and determined a posteriori to what extent the AB would have affected the crash. For those cases where the AB was evaluated as applicable, a further quantitative evaluation of the beneﬁts was conducted by considering a set of different possible rider reactions in addition to that exhibited in the actual crash. Results: In 67 percent of cases, the application of AB could have mitigated the crash outcome. Analysis of those real crash cases showed the potential for an expert rider to avoid the collision. An early reaction of the rider, associated with a correct application of the brakes would have avoided 18 of the 37 car following/crossing scenarios. Conversely, according to the analysis, an expert rider would not have been able to avoid 19 of the 37 cases. In 14 of those 19 cases, the AB would have contributed to mitigating the crash outcome. Conclusions: This study demonstrated signiﬁcant potential for application of the autonomous braking system in car following and crossing scenarios. In addition, the theoretical beneﬁt curves for the AB globally, were able to provide good quantitative indications of its beneﬁts in real cases where the AB was considered applicable. Further analysis with larger databases is suggested in order to conﬁrm the magnitude of beneﬁts in the PTW crash population. Supplemental materials are available for this article. Go to the publisher’s online edition of Trafﬁc Injury Prevention to view the supplemental ﬁle.