Quantitative analysis of rear-end crash causation mechanisms based on naturalistic crash data

Abstract

Until recently, little has been known about what exactly happens in the seconds leading up to a car crash. Due to the emergence of naturalistic driving data, e.g. video data of the forward roadway and of the driver combined with various sensor readings from real traffic incidents, it is now possible to research underlying crash causation mechanisms with much greater detail. An analysis of a 100 different rear‐end events, 70 crashes and 30 near‐crashes, was performed with the aim of replicating the findings of the SHRP2 naturalistic driving study performed by SAFER. The findings were in correspondence with those of the SHRP2 study; that rear‐end crashes usually occur due to a combination of glance duration and change rate of the situation kinematics, and that a short glance usually requires a rapid change in the situation kinematics while a longer glance could cause a crash even if the kinematic situation changes relatively slowly. The key mechanism behind crashes was found to be the timing of the last glance off the road relative to the change in urgency, represented optically by looming cues, during the glance. Brake lights were frequently ignored and the act of missing the brake light onset (BLO) in itself was not found to be a key mechanism in causing crashes and near‐crashes. Drivers that ended up in a crash were twice as likely to have looked away from the road after having seen the last BLO as those who ended up in a near‐crash.