Lateral Drift Warning (LDW) and Curve Speed Warning (CSW) systems were developed to address two main critical events in run-off-road crashes, whichare road edge departure and excessive speed. The LDW system used a two-stage alert system, with the first stage activating when the driver departeda lane with a dashed boundary and the imminent, or second stage, when departing a lane with a solid boundary. The CSW also employed a two-stage alert, with the level based on the degree of over-speed for the upcoming curve. The haptic modality, in the form of seat vibration, was chosen as the first level warning for both systems, and auditory was chosen as the secondor most urgent level. The two systems were installed in a fleet of instrumented vehicles and loaned to 78 randomly selected licensed drivers for approximately 4 weeks. Debriefing questions detailing the driver's experience with the system were administered and analyzed in a two by two design ofmodality by system. After examination of both the statistical results andthe open-ended comments, the question of which modality is most appropriate is still uncertain. Each modality had positive aspects. Haptic does notalert the entire car and participants also considered it less distracting. Auditory provided better recognition between warnings and participants were better able to understand the meaning and the required response for each warning.
Abstract