Date of Award


Publication Type


Degree Name



Civil and Environmental Engineering

First Advisor

C. Lee

Second Advisor

Y.H. Kim

Third Advisor

H. Moah


Driving simulator, Level 3 automated vehicle, Post takeover performance, Subjective mental workload, Takeover, Takeover time




The automotive industry is shifting towards partial (level 3) or fully automated vehicles. An important research question in level 3 automated driving is how quickly drivers can take over the vehicle control in response to a critical event. In this regard, this study develops an integrated takeover request (TOR) system which provides visual and auditorial TOR warning in both vehicle interface and personal portable device (e.g., tablet). The study also evaluated the effectiveness of the integrated TOR system in reducing the takeover time and improving post-takeover performance. For these purposes, 44 drivers participated in the driving simulator experiment where they were involved in secondary task (watching video on a tablet) in automated driving and they were requested to manually drive after the integrated TOR or the conventional TOR (which provides visual and auditorial TOR warning in vehicle interface only) was provided. Results from the statistical analysis suggest that the integrated TOR significantly reduced the takeover time and improved post-takeover performance as indicated by longer minimum TTC, shorter lane change duration, lower standard deviation of steering wheel angle and lower maximum acceleration during lane changing. The result also suggests that the integrated TOR can reduce the takeover time more effectively with the use of headphone. As more people are likely to use headphone in automated driving for better sound quality, understanding the effect of the use of headphone is critical for improving the effectiveness of the integrated TOR in reducing the takeover time. The results of subjective questionnaire show that the participants generally perceived higher subjective comfort and safety level with the integrated TOR system. Therefore, it is recommended to apply the proposed integrated TOR system for safe transition from automated to manual driving.