Effects of Traffic Clutter and Road Type on Road Hazard Detection

While operating a manually driven or even a highly automated vehicle, drivers may need to quickly perceive and respond to road hazards. In this study, we investigate several factors that might influence drivers’ ability to rapidly recognize road hazards in real-world settings. Using the publicly available Road Hazard Stimuli dashcam footage set, we divided stimuli into videos from highway and non-highway environments. We also developed the concept of “traffic clutter,” which is the area of the video screen containing other vehicles, and divided videos into those with high or low traffic clutter. Half the video clips showed road hazards occurring, and the other half showed another snippet from the same dashcam footage without a road hazard. Forty participants viewed these short, 233 ms video clips and responded whether they detected a road hazard or not. Using signal detection analyses, we show that drivers behave differently when responding to road hazards, depending on the context. First, participants were well above chance at detecting road hazards despite the short presentation times. Further, participants had higher sensitivity (d’) to road hazards when viewing videos with high traffic clutter. In terms of participants’ response criterion (c), we found that in both non-highway and high traffic clutter scenarios, drivers were more willing to commit false alarm rather than miss hazards. This difference in hazard response strategies may reflect biases drivers have developed during their time on the road.