Use of Parking and Auxiliary Lamps for Traffic Sign Illumination

摘要

In 1997, the U.S. government introduced an option of having headlamps labeled asvisually/optically aimable (VOA). To be so labeled, the vertical gradient of the light output needs to meet certain minimum requirements. A concern with VOA lamps is that they might provide less light above the horizontal than conventional U.S. lamps, thus reducing the effectiveness of retroreflective signs. This study examined 36 first-generation VOA lamps, to assess the reduction of light above the horizontal. Furthermore, this study addressed the possibility of maintaining the status quo of light for sign visibility, by supplementing light for VOA lamps with light from either parking lamps or an auxiliary lamp mounted just above the driver.