Influence of straylight on simulated driving performance

Abstract

Purpose: This study aimed to investigate how an increase in straylight (SL) affects the driving capability of healthy volunteers in various simulated driving circumstances. Methods: Participants were asked to (virtually) drive along a certain course in a driving simulator in four conditions: a regular drive (baseline), a drive in the presence of a glare source and a drive in the presence of a glare source while wearing two types of straylight filters (SLF1 and SLF2). The driving scenario included six different driving events (e.g. pedestrian crossing the road). The van den Berg straylight meter (Oculus C-Quant) was used to quantify the glare experienced by participants. Results: Twenty-one participants between the ages of 19 and 38 were included. There were significant differences in straylight measurements between the baseline and while wearing SLF1 and SLF2 (1.09 +/- 0.05, 1.34 +/- 0.04 and 1.49 +/- 0.02, respectively; ANOVA: P < 0.001). Over thirty driving parameters were analysed and significant effects of increased straylight was predominantly observed in the parameters pertaining to the events closest to the glare source (e.g., stationary motorcycle in the middle of the road). In those situations, significant increases in detection and reaction times were observed, as well as in stopping distance. In addition, increased glare hindrance prompted drivers to significantly reduce their speed. Conclusion: This experiment assessed how straylight, a visual parameter, affects driving behaviour and found that increased straylight leads to impairments in specific driving conditions, but also with some adaptions through compensatory strategies. These observations highlight the importance of straylight measurements to assess driving capability, particularly in those with glarerelated impairments.