Information is presented concerning all aspects of emergency-vehicle warning lights (EVWLs). A survey of the present situation includes: the non-uniformity of state EVWL laws; the factors entering into the choice of an EVWL configuration; a list and photographs of a variety of EVWL types; and a list of EVWL manufacturers and distributors. Background material relating to the perception of EVWL signals includes: an analysis of general warning-signal perception; a description of the visual stimulus pattern confronting a driver being approached by an emergency vehicle from various directions; and a summary of the characteristics of peripheral vision (including luminous efficiency, color perception and discrimination, and flicker and movement perception). Perceptual factors affecting the conspicuity of EVWL signals are discussed, including: effective intensity; flash rate; on-off ratio; pulse shape and flash duration; spatial sweep of beam; color; number and spatial pattern of lights; cross-sectional area; motion; temporal phase relations; and the role of the background. Physical measurements on EVWL units are described, including: angular intensity distribution and beamspread; flash rate; pulse shape and flash duration; effective intensity; color; and variables in rotating devices. A glossary, extensive enough to be helpful in reading the technical literature, is included.

  • Supplemental Notes:
    • Library of Congress Catalog Card no. 78-9503. Sponsored in part by National Inst. of Law Enforcement and Criminal Justice, Washington, DC.
  • Corporate Authors:

    National Bureau of Standards

    Gaithersburg, MD  United States 
  • Authors:
    • Howett, G L
    • Kelly, K L
    • Pierce, E T
  • Publication Date: 1978-9

Media Info

  • Pagination: 174 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00191620
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NBS-SP-480-16
  • Files: TRIS
  • Created Date: May 26 2002 12:00AM