Carryover Effects of Highly Automated Convoy Driving on Subsequent Manual Driving Performance

Objective: In the present study, we tested to what extent highly automated convoy driving involving small spacing (platooning) may affect time headway (THW) and standard deviation of lateral position (SDLP) during subsequent manual driving. Background: Although many previous studies have reported beneficial effects of automated driving, some research has also highlighted potential drawbacks, such as increased speed and reduced THW during the activation of semiautomated driving systems. Here, we rather focused on the question of whether switching from automated to manual driving may produce unwanted carryover effects on safety-relevant driving performance. Method: We utilized a pre-post simulator design to measure THW and SDLP after highly automated driving and compared the data with those for a control group (manual driving throughout). Results: Our data revealed that THW was reduced and SDLP increased after leaving the automation mode. A closer inspection of the data suggested that specifically the effect on THW is likely due to sensory and/or cognitive adaptation processes. Conclusion: Behavioral adaptation effects need to be taken into account in future implementations of automated convoy systems. Application: Potential application areas of this research comprise automated freight traffic (truck convoys) and the design of driver assistance systems in general. Potential countermeasures against following at short distance as behavioral adaptation should be considered.