The question of how well in terms of safety can a driver take over control of an automated vehicle in response to an emergency situation is of crucial importance. Most of the studies performed so far focus on the drivers’ reaction times and the mechanisms behind the transition. In this study, an effort is made to incorporate the braking times that are required in order to finalize a safety maneuver, with the aim to assess the safety implications of the entire transition in control. For this purpose, a new methodology was developed and a simulation model was used in order to simulate platoons of CACC equipped vehicles. Two new KPIs were defined: the Time to Control and the Safe Time Budget. The results suggest that higher number of critical events and crashes are associated with higher market penetration rates. This reveals that despite the fact that AV can in general increase traffic efficiency and safety, when it comes to emergency situations where safety is inextricably linked to the combination of AV and driver performance, overall safety may be compromised under certain conditions. In addition, the results revealed a strong connection of the above-mentioned action times with the initial speed of the vehicles involved in a conflict. The findings of this research, point to new directions particularly in concern to the extension of the operational design domain of automated vehicles in order to minimize system deactivations, and also with regard to the need for better prediction models and safety assessment tools.

Truck platooning is seen as a method to reduce truck emissions and labor hours in the transport industry. The effect that truck platooning will have on the other traffic receives less attention. In this thesis a methodology is proposed to model truck platoons, including a platoon level controller for lane changing. The model is used to estimate the on-ramp length that vehicles require in order to safely merge into the highway while interacting with platoons and the model is used to estimate the on-ramp length that truck platoons require in order to merge onto the highway if they would do so in platoon formation. Results show that onramps need to be at least 300 meters for other traffic to safely into the highway. For platoons to safely merge into the highway the required distance is heavily dependent on the crowdedness of the highway, ranging between 400-1000 meters of required on-ramp length.