A method to assess the safety implications of authority transitions in automated driving





authority transitions, Cooperative Adaptive Cruise Control, driver behavior, safety, simulation


Automated Driving Systems (ADS) are aimed to improve traffic efficiency and safety, however these systems are not yet capable of handling all driving tasks in all types of road conditions. The role of a human driver remains crucial in taking over control, if an ADS fails or reaches its operational limits. Takeover performance of human drivers in authority transitions is typically assessed by means of the takeover time (TOT) taken within an available time budget (TB). This approach assumes a uniform perception and reaction time of human drivers in ADS disengagements, and does not include the time needed to execute the actual driving maneuver required to ensure safety. This paper aims to develop and test a set of new indicators to reflect takeover performance and its safety attributes, namely the ‘time to control’ (TC) and the ‘safe time budget’ (STB), in which the actual task execution (i.e. braking) time is taken into account, in addition to the perception and reaction time. It also proposes new thresholds for identifying critical conflicts in takeover situations and assessing the safety of authority transitions. A traffic simulation experimental setup is used with mixed traffic of conventional vehicles and ACC/CACC platoons in order to test these indicators and thresholds. The results suggest that the time difference between TC and STB is a more sensitive and potentially more realistic safety indicator, as it may capture the variability of driver behavior in takeovers and identify critical conflicts, as well as virtual crashes, that would not have been identified by the previously used indicators (TOT and TB). Takeover performance worsens when the speed difference of the vehicles involved is higher, and the initial speed of the rear vehicle is higher. These findings can be useful towards a more dynamic design of takeover request strategies.


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Author Biographies

Eleonora Papadimitriou, Delft University of Technology, the Netherlands

Eleonora Papadimitriou is Associate Professor with Faculty of Technology, Policy, and Management of Delft University of Technology. She holds a Transportation Engineering diploma from the National Technical University of Athens (2001), a MSc in Transport from the Ecole des Ponts ParisTech (2003) and a PhD (2010) in Road Safety from NTUA. Eleonora's research is on transport safety, with emphasis on quantitative methods of risk assessment, and integration of interdisciplinary aspects of user behaviour, policy and ethical issues in transport safety.

CRediT contribution: Conceptualization, Investigation, Methodology, Writing—original draft.

Omiros Athanasiadis, Van Oord Marine Ingenuity, the Netherlands

Omiros Athanasiadis works as a Transport and Installation Engineer in the Offshore Wind industry for Van Oord Marine Ingenuity. He holds a diploma in Civil Engineering from Aristotle University of Thessaloniki (2016) and a MSc in Transport, Infrastructure and Logistics from TU Delft (2020). During his studies at TU Delft he did research on the safety impacts of authority transitions in automated driving, and developed the new safety indicators mentioned in this paper, that allow for a more accurate safety evaluation.

CRediT contribution: Data curation, Formal analysis, Methodology, Writing—original draft.

Gerdien Klunder, Netherlands Organisation for Applied Scientific Research, the Netherlands

Gerdien Klunder is a senior researcher in the field of traffic simulation. She completed her study Technical Mathematics in 2003. She is employed at TNO in the Research Group Sustainable Urban Mobility and Safety. She has more than 20 years of research experience with national and international projects in the areas of traffic management, traffic monitoring and prediction, modelling intelligent traffic systems, traffic safety and environmental effects of traffic. Also, she developed several microscopic traffic simulation frameworks for assessment of ITS measures. In 2010, she was temporary employed at VTT technical research centre of Finland. Her recent research focuses on the development of large scale microsimulation models for evaluation of automated driving and the expected effects on traffic safety and the environment.

CRediT contribution: Conceptualization, Methodology, Supervision, Writing—review & editing.

Simeon Calvert, Delft University of Technology, the Netherlands

Simeon C. Calvert is Associate Professor at the Faculty of Civil Engineering and Geosciences of Delft University of Technology. There, he is director of the Automated Driving and Simulation research lab and co-director of the CityAI research lab. He holds a PhD in transportation science from TU Delft (2016) and a MSc in Civil Engineering from TU Delft (2010). His research is focused on the impacts of automation and technology on traffic flow, which in particularly  includes vehicle-driver interaction and dynamics as well as aspects on responsible and ethical control of automated vehicles and systems.

CRediT contribution: Conceptualization, Methodology, Supervision, Writing—review & editing.

Lin Xiao, Netherlands Organisation for Applied Scientific Research, the Netherlands

Lin Xiao works as a mobility scientist at the Department of Sustainable Urban Mobility and Safety at TNO, the Netherlands. She holds a PhD in transportation science from Delft University of Technology (2020) and a MSc in Transportation Planning and Management from Tongji University (2014). Her research focuses on behavioral modelling of vehicles with and without different levels of vehicle automation, as well as traffic flow impacts analysis of combined effects of behavioral changes due to emerging vehicle innovations and traffic control technologies.

CRediT contribution: Methodology, Software, Writing—review & editing.

Bart van Arem, Delft University of Technology, the Netherlands

Bart van Arem is Full Professor at the Faculty of Civil Engineering & Geosciences and Pro Vice Rector Magnificus for Doctoral Affairs at Delft University of Technology. He holds an MSc (1986) and PhD (1990) in applied mathematics from the University of Twente. His research focuses on analysing and modelling the implications of intelligent transportation systems, such as automated, electric and shared vehicles. Such implications may vary from changes in driving and travel behaviour, traffic flows in networks and modal change, road and IT infrastructure and the spatial design of urban regions.

CRediT contribution: Conceptualization, Methodology, Supervision, Writing—review & editing.


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How to Cite

Papadimitriou, E., Athanasiadis, O., Klunder, G., Calvert, S., Xiao, L., & van Arem, B. (2024). A method to assess the safety implications of authority transitions in automated driving. Traffic Safety Research, 6, e000048. https://doi.org/10.55329/fkix6369