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Browsing by Author "Belz, Steven M."

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    Impact of Sleeper Berth Usage on Driver Fatigue, Final Project Report
    Dingus, Thomas A.; Neale, Vicki L.; Garness, Sheila A.; Hanowski, Richard J.; Keisler, Aysha S.; Lee, Suzanne E.; Perez, Miguel A.; Robinson, Gary S.; Belz, Steven M.; Casali, John G.; Pace-Schott, E. F.; Stickgold, Robert A.; Hobson, J. A. (United States. Federal Motor Carrier Safety Administration, 2002)
    The goal of this project was to assess the impact that sleeper berth usage has on operator alertness. Forty-seven males and nine females participated in this study, constituting 13 teams and 30 single drivers. All drivers who participated in this study were recruited from one of four for-hire commercial trucking companies. Two tractors, a 1997 Volvo L4 VN-series tractor and a 1995 Peterbilt 379, with functionally identical instrumentation packages and data collection systems, were used for the study. The data acquisition system functioned to record four camera views, including the drivers face; driving performance information, including steering, lane departure, and braking; sleeper berth environmental data, including noise, vibration, and temperature; subjective alertness ratings; and data from the Nightcap sleep-monitoring system. The following results were obtained: (1) Sleeping in either a stationary or moving sleeper berth was shown to adversely affect sleep quality and quantity when compared to the home sleep data. This was particularly true for team drivers in moving trucks. (2) Team drivers generally acquired more sleep (greater than one hour per day on average) than did single drivers, with single drivers reporting six hours of sleep per 24-hour period and team drivers reporting just over seven hours per 24-hour period. (3) Team drivers had significantly more sleep disturbances than did single drivers. A primary cause of these disturbances appeared to be noise and vibration present in the sleeper berth of a moving truck. (4) In general, single drivers were rated as not drowsy more often and team drivers, who were rated as somewhat drowsy or moderately drowsy more often. However, of the 20 very/extremely drowsy episodes captured by Observer Ratings of Drowsiness, 16 were from single drivers. (5) Single drivers had many more critical incidents at all levels of severity relative to team drivers. (6) The frequency of critical incidents and driver errors varied significantly by the Hour of Day. However, many more incidents occurred during the afternoon and early evening as opposed to late at night. (7) Single drivers were more alert in the morning and gradually become fatigued during the day, whereas team drivers maintained a relatively constant level of alertness throughout the 24-hour clock.
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    An On-Road Investigation of Commercial Motor Vehicle Operators and Self-Rating of Alertness and Temporal Separation as Indicators of Driver Fatigue
    Belz, Steven M. (Virginia Tech, 2000-09-06)
    This on-road field investigation employed, for the first time, a completely automated, trigger-based data collection system capable of evaluating driver performance in an extended duration real-world commercial motor vehicle environment. The complexities associated with the development of the system, both technological and logistical and the necessary modifications to the plan of research are presented herein This study, performed in conjunction with an on-going three year contract with the Federal Highway Administration, examined the use of self-rating of alertness and temporal separation (minimum time-to-collision, minimum headway, and mean headway) as indicators of driver fatigue. Without exception, the regression analyses for both the self-rating of alertness and temporal separation yielded models low in predictive ability; neither metric was found to be a valid indicator of driver fatigue. Various reasons for the failure of self-rating of fatigue as a valid measure are discussed. Dispersion in the data, likely due to extraneous (non-fatigue related) factors (e.g., other drivers) are credited with reducing the sensitivity of the temporal separation indicators. Overall fatigue levels for all temporal separation incidents (those with a time-to-collision equal to or less than four seconds) were found to be significantly higher than for those randomly triggered incidents. On this basis, it is surmised that temporal separation may be a sensitive indicator for time-to-collision values greater than the 4-second criterion employed in this study. Two unexpected relationships in the data are also discussed. A "wall" effect was found to exist for minimum time-to-collision values at 1.9 seconds. That is, none of the participants who participated in this research effort exhibited following behaviors with less than a 1.9-second time-to-collision criterion. In addition, based upon the data collected for this research, anecdotal evidence suggests that commercial motor vehicle operators do not appear to follow the standard progression of events associated with the onset of fatigue.
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    A Simulator-Based Investigation of Visual, Auditory, and Mixed-Modality Display of Vehicle Dynamic State Information to Commercial Motor Vehicle Operators
    Belz, Steven M. (Virginia Tech, 1997-11-11)
    This simulator-based study examined the use of conventional auditory warnings (tonal, non-verbal sounds) and auditory icons> (representational non-verbal sounds), alone and in combination with a dash-mounted visual display, to present information about impending collision situations to commercial motor vehicle operators. Brake response times were measured for impending front-to-rear collision scenarios under six display configurations, two vehicle speeds, and two levels of headway. Accident occurrence was measured for impending side collision scenarios under two vehicle speeds, two levels of visual workload, two auditory displays, absence/presence of mirrors, and absence/presence of dash-mounted iconic display. Subjective preference data was also obtained from participants. For both front-to-rear and side collision scenarios, auditory icons elicited significantly improved driver performance over conventional auditory warnings. Driver performance improved when collision warning information was presented through multiple modalities. Brake response times were significantly faster for impending front-to-rear collision scenarios using the longer headway criterion. The presence of mirrors significantly reduced the number of accidents for impending side collision scenarios. Subjective preference data indicated that participants preferred multi-modal displays over single-modality displays. A technique for systematically identifying, selecting, and evaluating candidate auditory icons was also developed. The potential exists to expand upon these developments, toward the goals of identifying appropriate auditory icons, improving operator performance, and developing information display techniques to effectively managing workload across multiple modalities.