In-Vehicle Decision Support to Reduce Crashes at Rural Thru-Stop Intersections


Caroline Hayes, Daniel Drew

August 2011

Report no. CTS 11-17

Purpose: Within the context of thru-stop intersections, investigate the feasibility and future promise of warning systems inside the vehicle, where interfaces are best placed, and what modalities are most effective (visual versus haptic). Methods: A driving simulator study was conducted to compare three decision support systems (DSSs): a dynamic traffic sign, a set of displays on the vehicle side mirrors, and a vibrating seat. Dependent variables included measurements of safe driving behavior, and a usability questionnaire. A follow-up focus group study was conducted to gain further feedback on the in-vehicle systems and on ideas for how to improve the systems. Results: The vibrating seat yielded significantly higher results than the dynamic traffic sign on two safety variables. No system clearly outperformed the others in terms of promoting safer driving behavior, nor did any improve driving performance compared to the control condition. The questionnaire and usability data showed that the dynamic traffic sign was most preferred, while the in-vehicle displays were most comprehended. Comments during the simulator studies suggested that participants wanted stronger advisory messages from the systems, and the Focus Group Study confirms this. Conclusions: In-vehicle DSSs appear to be feasible for the purposes of assisting drivers with navigating rural thru-stop intersections. No results of this study indicate that in-vehicle systems are an inherently poor means of presenting traffic gap information to the driver. Results indicate that a visual display would be easier to comprehend than a vibrotactile display when no training or explanation is provided.

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ITS Institute (RITA)