Copyright (c) 2013 University of Iowa All rights reserved. http://ir.uiowa.edu/ppc_human_factors Recent documents in Human Factors & Vehicle Safety Research en-us Mon, 20 May 2013 15:34:44 PDT 3600 http://ir.uiowa.edu/ppc_human_factors/2 http://ir.uiowa.edu/ppc_human_factors/2 Fri, 25 Sep 2009 14:05:48 PDT Adaptive cruise control (ACC) represents a rapidly emerging in-vehicle technology that can enhance or degrade driving safety. A critical factor governing the safety benefit of ACC concerns the ability of the driver to assume control of the vehicle in situations that exceed the capability of ACC. This study examined the effectiveness of various warning modalities in reengaging distracted drivers during severe braking situations that exceed the capability of ACC. The study compared warnings that paired a visual icon with an auditory cue, seat vibration, brake pulse, or a combination of all three cues. A total of sixty participants drove for 35- minutes in the National Advanced Driving Simulator (NADS). Drivers experienced two severe, four moderate, and eight mild braking situations. The ACC could accommodate all but the two severe situations without driver intervention. ACC provided a substantial benefit during mild braking lead vehicle events, enabling drivers to maintain a larger and more consistent minimum time-to-collision. Contrary to previous studies (Stanton, Young, & McCaulder, 1997), ACC did not produce a safety decrement during the severe braking situations. The combination of visual, auditory, seat vibration, and brake pulse led to slower brake reaction time in severe braking situations, but all four warning strategies led to a similar minimum time-to-collision and maximum braking. In contrast to several previous studies, these results suggest that drivers can effectively assume control when they receive a warning that the braking authority of ACC has been exceeded. Further research is needed to identify the boundary conditions that specify when drivers can successfully intervene and retake control and whether a multi-modal combination of cues can be crafted to speed rather than slow drivers’ response.

]]> Public Policy Center, The University of Iowa http://ir.uiowa.edu/ppc_human_factors/1 http://ir.uiowa.edu/ppc_human_factors/1 Fri, 25 Sep 2009 14:05:47 PDT The National Highway Traffic Safety Administration (NHTSA) has developed its Light Vehicle Antilock Brake Systems (ABS) Research Program in an effort to determine the cause(s) of the apparent increase in single-vehicle run-off-road crashes and decrease in multi-vehicle on-road crashes as vehicles transition from conventional brakes to ABS. As part of this program, NHTSA conducted research examining driver crash avoidance behavior and the effects of ABS on drivers’ ability to avoid a collision in a crash-imminent situation. The study described here was conducted on the Iowa Driving Simulator and examined the effects of ABS versus conventional brakes, speed limit, ABS instruction, and time-to-intersection (TTI) on driver behavior and crash avoidance performance. This study found that drivers do tend to brake and steer in realistic crash avoidance situations and that excessive steering can occur. However, a significant number of road departures did not result from this behavior. Drivers in the ABS group showed significantly increased stability and control relative to conventional brakes.

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