  Autonomous vehicles (AVs) are about to be used in transportation systems in
the near future. To increase the level of safety and throughput of these
vehicles, dedicated lanes for AVs have been suggested in past studies as
exclusive mobility infrastructure for these types of vehicles. Although these
lanes can bring obvious advantages in a transportation network, overall
performance of these lanes, especially in urban areas and in micro level sight,
is not clear. This study aims to examine the efficiency of dedicated lanes for
AVs in roundabout with an unbalanced traffic flow pattern. Four factors of
travel time, delay time, speed of vehicles, and queue of vehicles have been
selected as variables of traffic performance at the roundabout. Two microscopic
traffic simulation software, AIMSUN and SIDRA Intersection, were used to
examine the impact of the AV dedicated lanes at the roundabout. This study
shows that the effects of an imbalanced traffic pattern in a roundabout are
higher when the penetration rate of AVs is lower and also dedicated lanes in
roundabout's leg may improve traffic performance indicators when the
penetration rate of AVs is higher, but this improvement is not significant.
