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This study aimed to determine the usefulness of the Driver Assistive System (DAS) in the context of plowing roads during low-visibility conditions. Driving performance, driver workload, and system performance were to be compared in a field operational test (FOT). Geographical location of the driver's route proved to play a large part in the desirability and perceived reliability of the system, as rural drivers preferred the system due to the lack of lighting and visual guidance while driving in low-visibility conditions. Most drivers did not have problems remembering how to use the DAS, and that the system made them feel safer and more in control while driving. The haptic seat was praised for giving warnings while letting them keep their eyes on the road or performing other in-cab tasks and their ideal configuration would be to use the haptic seat and/or the HUD. Due to an uncharacteristically mild winter weather conditions, it was decided that the FOT would not provide enough experience using the DAS during low-visibility conditions to make reasonable conclusions on driving performance. Therefore, it was necessary to use an additional experimental design with a track test, which is discussed in a supplemental document (Rakauskas et al., 2003).

This track test supplements an attempted field operational test (Rakauskas et al., 2003) which did not provide enough experience using the Driver Assistive System (DAS) during low-visibility conditions to make reasonable conclusions on driving performance. This study aimed to determine the usefulness of the DAS in the context of simulated low-visibility conditions. Drivers drove in clear, low-visibility, and DAS-assisted low-visibility conditions. Driving performance measures were taken while driving and drivers were asked workload, trust, and subjective response questions after each condition and post-experiment. The DAS enabled drivers to maintain consistent lane position and to make fewer steering corrections than while driving the low-visibility condition. Using the DAS during low-visibility conditions did not change speed performance and aided the driver by providing additional information about the road. More mental effort was reported while assisted by the DAS than while driving unassisted in the low-visibility condition. This was expected since drivers were presented with and were expected to mentally process more information while assisted. Many of the trends found were consistent with our previous thoughts on how the DAS would perform. However, due to the small number of drivers tested in the FOT and track testing studies there was low power for our statistical analyses. We encourage further research with the DAS on larger numbers of drivers or in a more powerful study design. Some changes are also recommended for future versions, such as providing a warning prior to loss of GPS fix. Project study to assess the usefulness of the Driver Assistive System (DAS) in the context of driving snowplows in low-visibility conditions on a test track. The system was found to be useful; several design improvements to the system are suggested to maximize its effectiveness.

Report #4 in the series: Developing Intersection Decision Support Solutions. This report describes the human factors basis for an intersection decision support (IDS) system intended to improve the safety of rural intersections in Minnesota's Interregional Corridors (IRCs). The purpose of the human factors effort is to understand the task of rural intersection negotiation, identify high-risk user groups, describe the human factors that contribute to intersection accidents, and determine what conceptual types of information to present in the IDS display to improve driver performance and safety. Consistent with the original infrastructure consortium proposal, this report emphasizes gaps, older drivers, and rural thru-STOP intersections (Donath & Shankwitz, 2001). This is because older drivers have a high accident risk at rural thru-STOP intersections and problems with gap detection, perception, and acceptance are contributing factors. A task analysis of rural thru-STOP negotiation was used to define the informational requirements for an IDS system for assisting with gap detection, perception and judgment. An abstraction hierarchy defined the operator (driver) constraints relevant to an infrastructure-based IDS system. Four design concepts were constructed and tested in a driving simulator with older (55+) and younger (20-40) drivers in day and night driving conditions. Two designs resulted in the largest mean gap acceptance across groups when compared to baseline. The two design concepts also were most favored by the majority of participants.