Incandescent lamps are presently the major illumination source for traffic signals. They are, however, inefficient compared with other light sources. Maintenance costs are high for these lamps, and the light output degrades as the lamp ages. These problems--plus the ever-increasing cost of energy--justify considering other light sources. One alternative is light emitting diodes (LEDs). Before existing incandescent lamps are replaced by LEDs, it is necessary to show that LED signals will meet applicable standards for color and intensity, will not adversely affect the safety or operation of the roadway, and will be economically advantageous. NCHRP Project 5-12 was initiated in response to these needs. The objective of the research was to determine the feasibility and implementation potential of LEDs. The project found that red and Portland Orange (pedestrian) LED signals are currently feasible. This digest summarizes the project findings and includes testing results, a discussion of economic analysis, specification guidelines, recommendations for LED use, and suggested future research. The digest will be of interest to those involved in designing and specifying traffic signals.

  • Record URL:
  • Supplemental Notes:
    • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
  • Corporate Authors:

    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Publication Date: 1995-4


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; References; Tables;
  • Pagination: 11 p.
  • Serial:
  • Publication flags:

    Open Access (libre)

Subject/Index Terms

Filing Info

  • Accession Number: 00716797
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Feb 5 1996 12:00AM