This document is the Final Report on studies of roadway lighting and visibility. The purpose of these studies were fivefold: To identify a method for the quantification of visibility; To determine the precision of this method as a measure of motorists' visual performance; To develop a method of the specification of motorists' visibility needs; To develop a method for the prediction of the distribution of visibility along a roadway, and To develop warranting conditions affecting the level of visibility required for a variety of situational factors common to urban roadways. A visibility metric was developed which is based in well-documented psychophysical studies. This metric was shown to be a strong predictor of the visual performance of a large sample of unalerted motorists. A manual method for the calculation of the distribution of visibility along a roadway was developed. This method relies on luminance prediction procedures and yields values of a visibility index point-by-point along the roadway. The extensive calculations required for visibility "mapping" of a roadway provides evidence for the need for automated approach to lighting systems design. The problems of the development of warrants for roadway visibility are reviewed and concepts of potential application are highlighted. These include warrants based on opposing vehicle glare, a traffic conflicts rating system and roadway design speed. /FHWA/

  • Corporate Authors:

    Franklin Institute Research Laboratories

    Transportation Sciences Lab, Benjamin Franklin Parkway
    Philadelphia, PA  United States  19103
  • Authors:
    • Gallagher, V
    • Koth, B
    • Freedman, M
  • Publication Date: 1975-11

Media Info

  • Pagination: 146 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00179467
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-RD-76- 17 Final Rpt.
  • Contract Numbers: DOT-FH-11-8037
  • Files: TRIS, USDOT
  • Created Date: Aug 27 1978 12:00AM