Effects of directional auditory and visual warnings at intersections on reaction times and speed reduction times

Bella, Francesco; Silvestri, Manuel · 2017 · Crossref

DOI: 10.1016/j.trf.2017.09.006

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Summary

This study investigates the comparative effectiveness of directional auditory and visual warnings within Intersection Collision Warning Systems (ICWSs) on driver reaction times and braking behavior. Motivated by the high frequency of intersection-related accidents and the lack of empirical evidence comparing directional audio versus visual alerts, the research aims to determine which warning modality facilitates safer and more comfortable driver responses to potential collisions. The researchers conducted a driving simulator experiment involving 41 participants with valid European driving licenses. The experimental design utilized six rural road scenarios featuring stop-controlled intersections where a "violator" vehicle failed to stop and crossed the path of the test vehicle. The study employed a multi-factorial design comparing three warning conditions: no warning, a directional auditory speech message (e.g., "attention, vehicle from right"), and a directional visual warning (a red car icon oriented toward the threat). Warnings were triggered when the time-to-collision was approximately 4 seconds. Driver performance was evaluated using two key duration variables: reaction time (RT), defined as the time to initiate braking, and speed reduction time (SRT), defined as the duration of the deceleration maneuver. These variables were analyzed using an Accelerated Failure Time (AFT) duration model with a Weibull distribution, incorporating shared frailty to account for repeated measures from individual drivers. The results demonstrated that the presence of directional warnings, whether auditory or visual, enabled drivers to detect the violator vehicle earlier than in the no-warning condition. This earlier detection facilitated more comfortable braking maneuvers, characterized by longer speed reduction times and lower deceleration rates, thereby reducing the risk of abrupt, unsafe maneuvers. Crucially, the directional auditory speech message proved more effective than the visual warning. Drivers exposed to the auditory alert exhibited significantly lower reaction times and longer speed reduction times compared to those receiving visual alerts. This indicates that the auditory warning allowed for a more gradual and controlled speed reduction, whereas the visual warning resulted in faster but potentially more abrupt reactions. The significance of these findings lies in their implications for the automotive industry and the design of advanced driver assistance systems. The study concludes that directional auditory warnings are superior to visual warnings for improving intersection safety. By providing clear directional information through speech, ICWSs can help drivers anticipate hazards earlier and execute smoother braking actions, ultimately reducing the probability and severity of intersection collisions. These results suggest that future ICWS developments should prioritize directional auditory alerts to optimize driver response and enhance road safety.

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Topics

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• auditory warnings
• feedback modes
• multimodal feedback
• auditory
• perceptual countermeasures
• time to collision looming

Information type

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• Empirical Findings: behavioral performance data