Best Practices for Road Weather Management Version 2.0
Enhanced Night Visibility Series, Phase III?Study 2: Comparison of Near Infrared, Far Infrared, and Halogen Headlamps on Object Detection in Nighttime Rain
Enhanced Night Visibility Series Phase III, Study 2 (rainy weather) was performed following the same procedures used for Phase III, Study 1 (clear weather). Study 2 served to expand the knowledge of how current vision enhancement systems can affect detection and recognition of different types of objects while driving during adverse weather, specifically during rainy conditions. The empirical testing for this study was performed on the Virginia Smart Road; the rain was controlled by weather-making equipment. Fifteen participants were involved in the study. A 4 by 8 by 3 mixed factorial design was used to investigate the effects of different types of vision enhancement systems, different types of objects on the roadway, and driver's age on detection and recognition distances; subjective evaluations also were obtained for the different vision enhancement systems. The results of the empirical testing suggest that well-designed infrared (IR) systems are consistently associated with often significantly longer detection distances for most types of pedestrian objects during rainy conditions. In particular, the use of the near IR (NIR) systems resulted in earlier detection of nearly all tested pedestrian types than did the use of either far IR (FIR) or baseline halogen (HLB) systems. The exception to this finding is the case in which the pedestrian is on the right side of a right (1,250-m (4,101-ft) radius) curve. In this case, the NIR system was associated with similar or shorter (though not significantly so) detection distances than the FIR and HLB systems. Drivers in this study detected the nonpedestrian object (tire tread) at similar distances regardless of the headlamp system in use (NIR, FIR, or HLB). This indicates that there is no significant loss in detection distance for small, low-contrast objects (such as tire treads) among the types of headlamps tested in this study. All of these findings appear to be applicable regardless of driver age. Subjective comments by the drivers in this study tend to be consistent with the objective results discussed above.
Virginia Tech Transportation Institute, Prepared for FHWA Office of Safety Research and Development, FHWA-HRT-04-145
Williams, Gibbons, Hankey
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