Comparing Visual Fixations between Initially Stopped and In-motion Turn Across Path Hazards 2023-01-0837

Collisions involving turn-across-path hazards are responsible for a disproportionate number of injuries and fatalities compared to collisions with other orientations. Previous investigations of turn-across-path hazards have found conflicting results regarding hazard detection and response behaviour of drivers, particularly for hazards with different onset conditions. Typically, hazards with abrupt onsets should attract attention more readily, however, the opposite trend for response times has been observed when the abrupt onset is a rapid change in speed, rather than a sudden appearance. This study compared two left-turn-across path hazards with different onsets. The abrupt onset hazard was an initially stopped vehicle that quickly accelerated into the participant drivers’ path, while the gradual onset hazard was already in motion as the participant driver approached. Visual fixations were compared between the two onset types to determine if the sudden speed change was capturing attention as quickly as the already in-motion hazard, or if drivers were responding faster to the initially in-motion hazard for another reason. 88 participants completed the experiment in a full vehicle driving simulator while donning eye tracking glasses. Both response time and time-to-first fixation were shorter for drivers responding to the initially in-motion hazard when compared to the initially stopped hazard. There was no significant difference in total fixation duration between the onset conditions. The results indicate that despite the sudden onset behaviour, drivers were attending to the initially stopped hazard later. Additionally, for both hazard onsets time to first fixation duration was significantly, positively correlated with driver response time, while total fixation duration was significantly, negatively correlated. These differences in fixations provide evidence to include targeted instruction to address recognition of and responses to hazards with different onset conditions during driver training, and to include hazard onset behaviour as a consideration when evaluating the avoidability of collisions involving left-turning vehicles.