The development of high-intensity discharge (HID) sources for automotive headlighting has raised questions about the rendering of colors by those sources, relative to the rendering of colors by tungsten-halogen sources. The rendering of sign colors has been of concern because color is used as an indicator of sign functions. The rendering of the red of stop signs has been particularly of concern because consistent recognition of stop signs is critical for safety. This study was designed to compare the magnitudes of the shifts in chromaticity of stop signs illuminated by HID and tungsten-halogen headlamps to the range of chromaticities of stop signs under tungsten-halogen. A stratified sample of 25 stop signs was selected in Ann Arbor, Michigan. Stratification was by material (enclosed, encapsulated, microprism), age (more than five years in service, less than one year in service), and compass direction faced by the legend side of the sign (north, south). The chromaticities of these signs were measured in the field under both tungsten-halogen and HID (D1) illumination. The shifts between the chromaticities of the signs when they were illuminated with the tungsten-halogen source and when they were illuminated with the HID light source were moderate relative to the range of chromaticities under tungsten-halogen. The authors argue that, although the sizes of the shifts should not be interpreted as indicating a problem with color rendering by HID headlamps, they are not small enough to dismiss the possibility of a problem.

  • Corporate Authors:

    University of Michigan Transportation Research Institute

    2901 Baxter Road
    Ann Arbor, MI  United States  48109-2150
  • Authors:
    • Flannagan, M J
    • Sivak, M
    • Luoma, J
  • Publication Date: 1992-5


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 19 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00626660
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: UMTRI-92-17, HS-041 334
  • Files: HSL, TRIS, USDOT
  • Created Date: Jan 27 1993 12:00AM