The role of driver’s situational awareness on right-hook bicycle-motor vehicle crashes

The objective of this study was to explore the effect of driver Situational Awareness (SA) on 'right-hook' bicycle-motor vehicle crashes involving right turns into adjacent bicyclists. Previous literature suggests that improper allocation of motorists’ visual attention, inadequate surveillance, and poor SA are contributing factors to bicycle-motor vehicle crashes in other types of encounters. Fifty-one participants completed this driving simulator study. Right-turning motorists’ SA was measured using the SAGAT technique in the presence of a through-moving bicyclist in an adjacent bicycle lane during the latter portion of the green phase at a signalized intersection using a three (bicyclist’s relative position) by two (presence of oncoming left-turning vehicle) within-subject factorial design. Each participant made 21 right turns, nine of which were immediately followed by SA queries, and crash avoidance behavior was measured at the last intersection, which involved a crash-likely scenario.
Results of the study showed that the bicyclist’s position significantly influenced motorists’ overall SA (p < 0.05) and Level 2 SA (comprehension) (p < 0.05). Level 1 SA (perception) degraded when oncoming vehicles were present and the bicyclist was approaching from behind (p < 0.05). Level 3 SA (projection) degraded when the bicyclist was ahead of the motorist and oncoming vehicles were present (p < 0.05). Level 1 SA and crash occurrence were negatively correlated (rpbi = −0.3, p < 0.05). The study concludes that motorists focused more attention on cars in front of them and less attention on bicycles in the peripheral vision. A common cause of observed crashes in the simulator was detection error. The bicyclist approaching from behind the motorist is the most vulnerable to a right-turning motorist.