What Drivers Know and Think They Know During Takeover: Effects of Spatial Risk, Temporal Risk, and NDRT on Situation Awareness

Safety interventions in conditionally automated vehicles depend on drivers’ situation awareness (SA) across contexts involving spatial location and temporal urgency. This complexity increases when drivers perform non-driving tasks (NDRTs), which divert attention before a takeover request. Traditional SA measures often rely on a single accuracy score, which may obscure true understanding, confidence, or response bias. This study addressed these issues by examining spatial risk dimensions (forward path vs. adjacent lane), temporal risk dimensions (imminent vs. projected threats), and NDRT engagement, using the Quantitative Analysis of Situation Awareness, which separates SA into actual SA (ASA), perceived SA (PSA), and response bias. Sixty-six participants took part in this video-based study. Results showed that the spatial risk dimension significantly affected ASA, PSA, and response bias; the temporal risk dimension affected ASA and PSA; and NDRT affected only PSA. These component-level patterns across risk dimensions identify diagnostic targets for developing future takeover support systems.