Effects of hazard exposure and roadway complexity on young and older driver situation awareness and performance

Few previous studies of driver situation awareness (SA) have focused on behavior in hazard negotiation. The objective of this research was to assess the effect of hazard exposure on driver SA and interactions with age and roadway complexity. Ten young (18–25 yrs) and ten older (65–81 yrs) participants drove in a simulator under two levels of environment complexity (simple – rural vs. complex – city) with two types of hazard exposure (static vs. dynamic). Situation awareness was measured using real-time probes posed by a confederate passenger. Driving performance was assessed in terms of lane maintenance and speed control. Results revealed hazards to cause degradations in high level of driver SA and speed control or to trigger adaptation, and vulnerability to hazard type was dependent on driver age. Older drivers exhibited greater speed reduction in response to dynamic hazards; whereas, young driver maintained higher speed, as compared to normal driving, when confronted with static hazards. In addition, increased roadway environment complexity compounded decrements in performance caused by hazard exposure. These findings are applicable to modeling driver behavior and SA under hazardous conditions and may support the design of new in-vehicle assistive technologies for hazard avoidance.