A driving simulator study for evaluating driving performance during car-following manoeuvre after a transition from automated to manual control

The recent literature concerning autonomous vehicles has demonstrated them to be capable of bringing several benefits, by both reducing traffic congestion and emissions and improving transportation accessibility. Until the highest level of automation will not be achieved, humans will remain an important part of the driving loop, which involves the need for a deeper comprehension of their role in the driving automation. A challenging research topic consists in understanding whether an automation period is likely to reduce drivers’ fatigue rather than increase their distraction, especially when they have been inattentive or involved in a secondary task during conditional or highly automated driving. The main objective of the research consists in assessing the effects of an automation period on the drivers, in terms of driving performance and safety implications. A specific focus is set on the car-following manoeuvre. A driving simulator experiment has been designed to the purpose. In particular, each participant was requested to drive a virtual scenario twice, with a level-three driving automation: one drive having Manual Control Mode; the other drive having Automated Control Mode activated during half of the scenario. During the automation mode, the drivers were asked to watch a movie inside the vehicle on a tablet. When the drivers were required to take over the control of the vehicle, two car-following manoeuvres were set to occur due to a slow vehicle on the right lane and a platoon of vehicles in the passing lane that discouraged the passing manoeuvre. Various driving performances (speeds, accelerations, etc.) and surrogate safety measures (PET and TTC) were collected and analysed focusing the car-following manoeuvres. Results confirmed the analysis of driving performance after a period of automated driving as a crucial topic in the on-going path to a full automation