Due to the advancement in technology, it is likely to witness a deployment of Autonomous Vehicles (AV) on the road in the near future. High technical capability of AVs is expected to create different behavioral settings than Human-Driven Vehicles (HDV), such as shorter reaction time and time headway. However, considering AV-HDV mixed traffic conditions in the process of the dissemination, radical behavioral settings of AV might have negative impacts on traffic flow. This paper investigates safety, efficiency and comfort impacts of AV on a single lane motorway considering different reaction time, time headway and percentage of AV in a vehicle platoon. Results of Monte Carlo simulation show that with increased percentage of AV, safety, efficiency and comfort can be improved as far as the time headway of AV is similar to HDV under the assumption that AVs have smaller reaction time than HDVs. However, it can be concluded that the smaller desired minimum time headway may cause the unsafe and uncomfortable condition with the longer reaction time. Therefore, the setting of AV should be carefully selected considering the relationship between the reaction time and the desired minimum time headway.