Advanced Driver Assistance Systems (ADAS) play a crucial role in enhancing road safety and driver comfort by providing real-time alerts and support. However, the effectiveness of ADAS signals in influencing driver situational awareness (SA) remains an area requiring further investigation. This study examines how different ADAS speed limit alert designs impact the three levels of SA: perception, comprehension, and projection.

A real-world driving experiment was conducted in Amersfoort along a 4.3 km route, comparing two ADAS systems with distinct signal designs. System A provided both the current and upcoming speed limits, while System B displayed only the current limit. Data collection included eye-tracking for SA1 (perception), self-reported questionnaires for SA2 (comprehension), and speed analysis for SA3 (projection). Statistical analyses, including significance tests, correlation analysis, and Linear Mixed Models (LMM), were employed to evaluate the influence of ADAS design and driver-related factors on SA.

Results indicate that while most SA indicators did not show significant differences between the two ADAS systems, System A consistently demonstrated advantages in visual attention allocation and comprehension. Additionally, driver experience and familiarity with ADAS were found to influence SA, with experienced drivers exhibiting reduced cognitive load and faster responses. A weak correlation between different SA levels suggests that drivers integrate ADAS alerts with external environmental cues.

This study highlights the importance of designing ADAS alerts that provide anticipatory information to enhance driver awareness and decision-making. Future research should expand sample sizes, incorporate additional SA indicators, and explore the long-term effects of ADAS exposure. These findings offer valuable insights for optimizing ADAS signal design to improve road safety and driving performance.