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This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-HRT-04-149
Date: December 2005

Enhanced Night Visibility Volume XVIII Overview of III

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Phase III was the final part of the three-phase Enhanced Night Visibility (ENV) project, whose initial goal was to study supplemental ultraviolet band A (UV–A) headlamps and supporting infrastructure to improve night visibility. The results of ENV Phase II indicated that UV–A is not a viable technology for automotive implementation in the foreseeable future. Infrared (IR) technology, however, did show some promise in Phase II as a viable supplemental vision enhancement system (VES) for automobiles. Given these two findings, the Phase III effort was refocused from testing UV–A headlamps on public roads to testing other promising alternative vision enhancement systems, including IR technology, on the Virginia Smart Road. The refocused Phase III effort was driven by the fundamental objective to evaluate methods with the potential to improve visibility of the road environment.

The Phase III effort included two studies that evaluated the performance of near IR (NIR) systems, an IR thermal imaging system (IR–TIS), high intensity discharge (HID) headlamps, and halogen headlamps at night in clear weather and rain, respectively. The primary dependent measures for these visual performance studies were detection and recognition distances of signs, pavement arrows, road debris, and pedestrians in multiple locations on the road. Some pedestrians were positioned away from the edge of the road to determine potential benefit of the additional roadside illumination provided by some HIDs. A third study assessed discomfort and disability glare for the halogen baseline and HID baseline VESs used in Phase II and three HID VESs. A subsequent analysis was performed to characterize the luminance of the objects with each VES included in the visual performance studies. The following four volumes fully detail Phase III:

  • Volume XIII: Enhanced Night Visibility Series: Phase III—Study 1: Comparison of Near Infrared, Far Infrared, High Intensity Discharge, and Halogen Headlamps on Object Detection in Nighttime Clear Weather (FHWA-HRT-04-144).

  • Volume XIV: Enhanced Night Visibility Series: Phase III—Study 2: Comparison of Near Infrared, Far Infrared, and Halogen Headlamps on Object Detection in Nighttime Rain (FHWA-HRT-04-145).

  • Volume XV: Enhanced Night Visibility Series: Phase III—Study 3: Influence of Beam Characteristics on Discomfort and Disability Glare (FHWA-HRT-04-146).

  • Volume XVI: Enhanced Night Visibility Series: Phase III—Characterization of Experimental Objects (FHWA-HRT-04-147).

In addition, Volume XVII—Characterization of Experimental Vision Enhancement Systems (FHWA-HRT-04-148)—details the characterization of the vision enhancement systems used in this phase.

This report summarizes the independent variables, dependent variables, and key findings for the visual performance studies and the disability glare study in Phase III.


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