AN INSTRUMENT FOR ASSESSMENT OF VISIBILITY UNDER HIGHWAY LIGHTING CONDITIONS

THERE IS CURRENTLY NO GENERALLY ACCEPTED OBJECTIVE METHOD FOR THE DETERMINATION OF VISIBILITY OF OBJECTS IN HIGHWAY TRAFFIC LANES AT NIGHT UNDER HIGHWAY LIGHTING CONDITIONS. VISIBILITY APPRAISAL METHODS ARE GENERALLY SUBJECTIVE IN NATURE, WITH WIDE VARIANCE AMONG OBSERVERS. THIS PAPER PROVIDES AN ANALYSIS OF THE PROBLEM OF VISIBILITY ASSESSMENT UNDER HIGHWAY LIGHTING CONDITIONS AND EVALUATES MANY OF THE FACTORS UNDER THESE CONDITIONS. THE FINDINGS OF THIS INVESTIGATION HAVE RESULTED IN A MATHEMATICAL ANALYSIS OF VISUAL ASSESSMENT AND PERMIT THE ESTABLISHMENT OF VISIBILITY CRITERIA FOR HIGHWAY LIGHTING. THE INSTRUMENT DESCRIBED PROVIDES AN OBJECTIVE DETERMINATION OF RELATIVE VISIBILITY. THE DEVICE CONSISTS OF A DUAL MONOCULAR SYSTEM WITH SUITABLE OPTICAL WEDGES ARRANGED TO REDUCE A 2 DEGREE CENTRAL PORTION OF THE ROADWAY AREA UNDER OBSERVATION TO A CONTRAST THRESHOLD, WHILE MAINTAINING A CONSTANT EYE ADAPTATION, THUS PROVIDING A RELATIVE INDEX OF VISIBILITY. THE VISIBILITY INDEX IS CALIBRATED IN TERMS OF THE CONTRAST BETWEEN AN OBJECT OF FIXED SIZE AND ITS BACKGROUND. THE FINDINGS OF THIS INVESTIGATION PROVIDE RATIONAL DESIGN CRITERIA FOR HIGHWAY LIGHTING, ENABLE THE PREDICTION OF THE VISUAL PERFORMANCE OF A HIGHWAY LIGHTING DESIGN, AND PROVIDE AN OBJECTIVE VISUAL APPRAISAL METHOD FOR THE COMPARATIVE EVALUATION OF VISIBILITY OF EXISTING HIGHWAY LIGHTING SYSTEMS. /AUTHOR/

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/336/336-009.pdf
• 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.
• Authors:
  • Simmons, A E
• Conference:
  • 41st Annual Meeting of the Highway Research Board
  • Location: Washington DC, United States
  • Date: 1962-1-8 to 1962-1-12
• Publication Date: 1962

Media Info

• Media Type: Digital/other
• Features: Figures; References;
• Pagination: pp 76-94
• Monograph Title: Night visibility 1962
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 336
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Design; Mathematical analysis; Measuring instruments; Night; Night visibility; Street lighting; Visibility
• Uncontrolled Terms: Design criteria
• Subject Areas: Design; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00220122
• Record Type: Publication
• Files: TRIS, TRB, ATRI
• Created Date: Aug 5 1994 12:00AM