REVIEW OF VISIBILITY FACTORS IN ROADWAY SIGNING-WITH DISCUSSION

SIGN PERFORMANCE IS DEPENDENT ON ATTENTION VALUE AND LEGIBILITY AND THESE ARE FUNCTIONS OF TARGET VALUE AND PRIORITY VALUE, PURE LEGIBILITY AND GLANCE LEGIBILITY RESPECTIVELY. EACH FACTOR IS RELATED DIRECTLY TO CONTRAST. IT HAS BEEN SHOWN THAT LEGIBILITY DISTANCE CHANGES WITH THE FOLLOWING PARAMETERS: LETTER HEIGHT, WIDTH, SPACING, CONTRAST, AND BRIGHTNESS. EACH OF THESE PARAMETERS INTERACT WITH AND INFLUENCES THE OTHERS. FAMILIAR WORDS ARE SEEN AT LONGER DISTANCES. SCRAMBLED LETTER DETERMINATIONS GIVE BETTER RELIABILITY, AND THE DISTANCES ARE MORE REPRESENTATIVE OF THE 20/40 VISION OF MANY DRIVERS. RELATIVELY HIGH SIGN LUMINANCE IS NEEDED AGAINST COMPARATIVELY BRIGHT SURROUNDINGS, BUT USUALLY NOT FOR ORDINARY RURAL ROADS. STUDIES HAVE FOUND THAT THE MAJOR FACTORS AFFECTING TARGET VALUE ARE THE SIGN COLOR AND BRIGHTNESS, PRODUCING CONTRAST WITH THE NATURAL BACKGROUND OR SURROUNDINGS. FOR OPTIMUM TARGET VALUE THE SIGN SHOULD FALL WITHIN A SPECIFIED VISUAL CONE. THE RESULTS OF COMPUTER ANALYSIS OF LUMINANCE VARIABLES ARE REVIEWED. REQUIREMENTS OF A BASIC INFORMATION SYSTEM WHICH MUST BE COMPATIBLE WITH THE WORST-CASE DRIVER ARE LISTED. THE VISUAL COMMUNICATION SYSTEMS ON FREEWAYS, ARTERIAL STREETS, AND 2-LANE HIGHWAYS WAS EVALUATED USING A DIAGNOSTIC TECHNIQUE. THE RESULTS OF THE STUDY IN THE AREAS OF SIGNS, URBAN SIGNING, PAVEMENT MARKINGS, AND DELINEATION ARE REVIEWED. A DIAGRAMATIC SIGN STUDY IS DESCRIBED AND OBSERVATIONS ARE MADE ON THE DIRECTION OF FUTURE RESEARCH. THIS REPORT IS FOLLOWED BY A DISCUSSION IN WHICH LEGIBILITY DISTANCES, LUMINANCE, AND CONTRAST ARE AMONG THE FACTORS REVIEWED.

• Record URL:
  • http://onlinepubs.trb.org/Onlinepubs/sr/sr134/sr134-004.pdf
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309020972
• 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:

  Highway Research Board

  2101 Constitution Avenue, NW
  Washington, DC    20418
• Authors:
  • WOLTMAN, H L
• Discussers:
  • Forbes, T W
  • Olsen, Richard A
• Conference:
  • Workshop on Highway Visiblity
  • Location: St Paul Minnesota, United States
  • Date: 1972-7-18 to 1972-7-20
• Publication Date: 1973

Media Info

• Media Type: Digital/other
• Features: References;
• Pagination: pp 28-40
• Monograph Title: HIGHWAY VISIBILITY
• Serial:
  • Highway Research Board Special Report
  • Issue Number: 134
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Attention value; Brightness; Highway delineators; Legibility; Research; Reviews; Road markings; Signs; Strategic planning; Visibility
• Old TRIS Terms: Delineators (Traffic); Traffic marking
• Subject Areas: Highways; Research; Safety and Human Factors;

Filing Info

• Accession Number: 00222186
• Record Type: Publication
• ISBN: 0309020972
• Files: TRIS, TRB, ATRI
• Created Date: Apr 20 1974 12:00AM