REQUISITE LUMINANCE CHARACTERISTICS FOR REFLECTIVE SIGNS

SIGNING ON URBAN AND RURAL ROADWAYS EXHIBITS A COMPLEX OF SIGN POSITIONS AND AMBIENT ILLUMINATION LEVELS SUGGESTING NEED FOR DETERMINING OPTIMUM CHARACTERISTICS FOR RETRO- REFLECTIVE MATERIALS UNDER THESE CONDITIONS. OTHER STUDIES HAVE EVALUATED AVAILABLE REFLECTIVE MATERIALS FOR INDIVIDUAL EFFECTIVENESS. THIS STUDY IS DESIGNED TO ESTABLISH REFLECTIVE CHARACTERISTICS REQUIRED FOR ANY INSTALLATION AND SUGGESTS A BRIGHTNESS RANGE FOR TYPICAL SIGN ENVIRONMENTS. IDEALLY, CONSISTENT LUMINANCE WOULD BE MAINTAINED THROUGH APPROACH DISTANCES FOR ALL SIGN POSITIONS. ISO-ILLUMINANCE AND ISO-DIVERGENCE DATA INDICATE VARYING ILLUMINANCE AND RETRO-REFLECTIVE EFFICIENCY THROUGHOUT THE APPROACH. HOWEVER INVERSE RELATIONSHIP AT GENERALLY USEFUL DISTANCES INDICATES LITTLE MODIFICATION OF THE CLASSIC DIVERGENCE CURVE IS NECESSARY FOR MATERIALS CONSIDERED. AMBIENT ILLUMINATION OF SIGN SURFACES COMMONLY RANGES FROM 0.4 FOOT-CANDLES IN ILLUMINATED AREAS TO LESS THAN 0.1 IN RURAL LOCALES. CURRENT REFLECTIVE MATERIALS PROVIDE GOOD HIGH BEAM PERFORMANCE AND ADEQUATE LOW BEAM PERFORMANCE WHERE AMBIENT ILLUMINATION INCIDENT ON THE SIGN SURFACE DOES NOT EXCEED 0.4 FOOT- CANDLES. IN EXCESS OF 0.4 FOOT-CANDLES, STREAM TRAFFIC PROVIDES ADDITIONAL USEFUL LUMINANCE. SUFFICIENCY VALUES FOR SIGN LUMINANCE ARE PRESENTED FOR DARK AND ILLUMINATED LOCALES. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/336/336-007.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:
  • Elstad, J O
  • Fitzpatrick, J T
  • WOLTMAN, H L
• 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; Tables;
• Pagination: pp 51-60
• Monograph Title: Night visibility 1962
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 336
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Brightness; Legibility; Light; Materials; Reflection; Reflective signs; Reflectorized materials; Rural highways; Traffic signs; Urban highways
• Old TRIS Terms: Traffic sign materials
• Subject Areas: Highways; Materials; Safety and Human Factors;

Filing Info

• Accession Number: 00220120
• Record Type: Publication
• Files: TRIS, TRB, ATRI
• Created Date: Aug 5 1994 12:00AM