Enhancing Older Drivers’ Safety and Experience: Effects of AR-HUD Display Position, Indication Distance, Gradient Transparency, and Graphic Animation

Drivers in complex traffic environments face high cognitive demands, increasing accident risk, especially for older drivers. Augmented reality head-up displays (AR-HUD) can improve safety by projecting navigation cues directly into the forward view, yet age-specific guidelines for different traffic contexts are scarce. This study examines four AR-HUD design factors: display position (aerial or ground), indication distance (long or short), gradient transparency, and graphic animation. In a simulated congestion scenario, an aerial display paired with long-distance indication shortened first-fixation latency and reduced total fixation duration when visibility was clear. Gradient transparency combined with subtle animation further lowered braking reaction time. The results show that optimal configurations vary with traffic context. Long-distance aerial cues support early route planning on unobstructed roads, whereas short-distance ground-level cues maintain information visibility when the forward view is blocked. These evidence-based recommendations provide practical guidance for designing AR-HUD interfaces that enhance perceptual efficiency and driving safety for older drivers in complex urban settings.