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Federal Highway Administration Research and Technology
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Publication Number: FHWA-HRT-04-132
Date: December 2005
Enhanced Night Visibility, Volume I: Executive Summary
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The results indicated that UV–A does have the potential to allow greater detection of pedestrians dressed in clothing with fluorescent properties. This potential exists in clear as well as inclement weather. Additional glare from oncoming UV–A sources does not appear to create additional discomfort glare to other drivers. Adding fluorescent pigment to pavement markings appears to have no benefit. Overall, due to the cost, power consumption, and size, supplemental UV–A is not sufficiently beneficial at enhancing night visibility to justify additional research in this area. If improvements to UV–A technology were to overcome these barriers, further research may be worth considering again.
The current supplemental IR systems, on the other hand, have the potential to greatly enhance pedestrian detection and safety. This is particularly true for pedestrians dressed in nonreflective, dark clothing. Near IR systems, specifically, have the potential to improve pedestrian visibility in adverse weather conditions.
It is important to note that this research did not assess how attention to an IR display of the forward road scene may distract drivers from other driving activities or at least create a time-sharing dilemma. There was some indication that, for objects not presented in the IR display, the object detection distances were shorter for participants driving with the IR display than for those driving without a display. Future research should evaluate methods to alert the driver when an important object is present, and these methods should not rely on the driver noticing the object through normal scanning of the display. Such an alert could potentially highlight objects on the display or eliminate the display entirely and use another mechanism to alert drivers.
Perhaps the most important lesson to be derived from this research is that a well-designed implementation, not just the use of a technology, is a key to a successful enhanced night visibility system. For example, claiming that all HID headlamps significantly improve visibility but also significantly increase glare is oversimplified; in this research, there were HID headlamps that did not significantly improve visibility and HID lamps that did not cause significantly worse glare. In addition, one NIR system in the clear weather condition outperformed headlamps, but another NIR system performed worse than headlamps. In general, different implementations of a given technology may yield significantly different performances. Results should not be generalized across a technology but should be tied to the particular implementation of that technology.