The effects of adverse condition warning system characteristics on driver performance: an investigation of alarm signal type and threshold level

This study addresses the issues concerning the design of adverse condition warning systems (ACWS). ACWS are designed to sense adverse road and weather conditions as well as system states that can negatively impact driving performance leading to skids or accidents, and alert drivers to these conditions. In this case, an ACWS was designed to sense when a car was likely to skid. A virtual-driving environment was used to test two levels of alarm sensitivity (low and high) and two types of auditory alarm signal (Binary ON/OFF and Graded) along with a no-alarm control group. Dependent measures re ̄ected driver performance, response to the alarm signal and trust in the alerting system. Results indicated that participants had fewer skids in the low sensitivity and graded alarm signal condition compared to some other alerting system con®gurations. Participants in the graded alarm signal condition also had a greater degree of lateral control over the vehicle. Additionally, trust was found to be lower for the high vs. low sensitivity alarm condition, indicating a reduction in trust when the alerting system activated more often, perhaps because participants did not feel the system was accurately re ̄ecting a dangerous condition. This simulator-based research emphasizes the fact that while ACWS may provide an advantage in terms of vehicle control, characteristics of both the alerting signal and system con®guration should be considered.