Date of Award


Publication Type

Master Thesis

Degree Name



Civil and Environmental Engineering


Adaptive Cruise Control, Aimsun, Autonomous Car, Autonomous Truck, Autonomous Vehicles, Cooperative Adaptive Cruise Control


Chris Lee


Yong Hoon Kim




This study recommends strategies to reduce the delay time and increase comfortability of Autonomous Car (AC)-Autonomous Truck (AT) mixed traffic. Several scenarios were tested to evaluate the effects of Adaptive Cruise Control (ACC)/Cooperative Adaptive Cruise Control (CACC) on Autonomous Vehicles’ (AVs) delay time, merging time and comfortability using sensitivity analysis. Also, the simultaneous effects of different percentages of ATs and various time gaps on the delay time were analyzed. The study was conducted on a 5.25 km-long freeway including a merge area using AIMSUN. It was found that 1) increasing the sensitivity to speed and distance errors was not an appropriate strategy since not only it did not reduce the delay and merging times, but it also decreased the comfortability, 2) shorter time gaps between AVs and between platoons decreased the delay and merging times, but it decreased the comfortability of AVs. Hence, there is a trade-off between reduction in delay time and driver’s comfort in shorter time gaps, 3) Maximum platoon size did not affect the delay and merging times significantly, while it increased the comfortability. Thus, a higher maximum platoon size can be effective, 4) cooperative lane-changing (CLC) led to the highest increase in speed of AVs in the on-ramp and the merge sections. However, CLC caused less comfortability, and 5) as the percentages of ATs increased, longer time gaps could be adopted for AVs so that the delay time reduced more significantly. In general, shorter time gaps and CLC decreased the delay and merging times, while both decreased the comfortability. And, higher maximum platoon size did not affect the delay and merging times, while increased comfortability. Thus, it is recommended to develop more advanced AV control strategies with the balance between the delay and comfortability based on the time gaps, platoon size and CLC.