Abstract
There is evidence that drivers’ behaviour adapts after using different advanced driving assistance systems. For instance, drivers’ headway during car-following reduces after using adaptive cruise control. However, little is known about whether, and how, drivers’ behaviour will change if they experience automated car-following, and how this is affected by engagement in non-driving-related tasks (NDRT). The aim of this driving simulator study, conducted as part of the H2020 L3Pilot project, was to address this topic. We also investigated the effect of the presence of a lead vehicle during the resumption of control, on subsequent manual driving behaviour. Thirty-two participants were divided into two experimental groups. During automated car-following, one group was engaged in an NDRT (SAE Level 3), while the other group was free to look around the road environment (SAE Level 2). Both groups were exposed to Long (1.5 s) and Short (.5 s) Time Headway (THW) conditions during automated car-following, and resumed control both with and without a lead vehicle. All post-automation manual drives were compared to a Baseline Manual Drive, which was recorded at the start of the experiment. Drivers in both groups significantly reduced their time headway in all post-automation drives, compared to a Baseline Manual Drive. There was a greater reduction in THW after drivers resumed control in the presence of a lead vehicle, and also after they had experienced a shorter THW during automated car-following. However, whether drivers were in L2 or L3 did not appear to influence the change in mean THW. Subjective feedback suggests that drivers appeared not to be aware of the changes to their driving behaviour, but preferred longer THWs in automation. Our results suggest that automated driving systems should adopt longer THWs in car-following situations, since drivers’ behavioural adaptation may lead to adoption of unsafe headways after resumption of control.
Highlights
Advanced Driver Assistance Systems (ADAS), such as Adaptive Cruise Control (ACC) or Lane-Keeping Support (LKS) systems, have become a common feature of modern vehicles
We investigated if monitoring the environment, and seeing the headway maintained by the Automated Driving Systems (ADS) (L2), resulted in a different subsequent manual car-following behaviour, compared to situations which did not require driver monitoring (L3)
The Time Headway (THW) distributions generally followed the distributions observed in other studies, with the exception of the Baseline Manual Drives and the post-automation drives in which drivers experienced a Long THW and resumed control when there was no lead vehicle
Summary
Advanced Driver Assistance Systems (ADAS), such as Adaptive Cruise Control (ACC) or Lane-Keeping Support (LKS) systems, have become a common feature of modern vehicles. Less is known about how/if the longer term effects of automation engagement affects drivers’ subsequent manual driving performance, and whether this is influenced by engagement in NDRTs (Metz et al 2020). In addition to understanding the instant effects of such resumptions of control on performance, for collision avoidance and hazard perception, it is important to assess how they affect less critical driving scenarios, and whether they influence drivers’ already well-established behaviours during manual vehicle control (behavioural adaptation). We investigated if monitoring the environment, and seeing the headway maintained by the ADS (L2), resulted in a different subsequent manual car-following behaviour, compared to situations which did not require driver monitoring (L3). Before describing the methods used, the sections provide a short overview of car-following and behavioural adaptation research
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