SAFETY HAZARD OF TINTED AUTOMOBILE WINDSHIELDS AT NIGHT

THE EFFECTS OF TINTED OPTICAL MEDIA, PARTICULARLY OF HEAT-OBSORBING AUTOMOBILE WINDSHIELDS, UPON VISIBILITY DISTANCES ON THE HIGHWAY AT NIGHT ARE ANALYZED THEORETICALLY. THE LOSS PERCENTAGES IN VISBILITY DISTANCES CAUSED BY REPLACING CLEAR WINDSHIELDS WITH TINTED ONES ARE CALCULATED AS FUNTIONS OF THE VARIABLES INVOLVED, VIZ., TRANSMITTANCE OF THE TINTED OPTICAL MEDIUM, ISOCANDLE PROFILE OF THE HEADLAMP, ANGULAR SIZE AND REFLECTANCE OF THE TARGET. IT IS FOUND THAT THE LOSS PERCENTAGES IN VISIBILITY DISTANCES ARE FURTHER DEPENDENT UPON THE DISTANCE OF THE TARGET ITSELF, WITH THE LOSSES INCREASING WITH DECREASING DISTANCES. LOSSES IN VISIBILITY DISTANCES CAUSED BY COMMERCIAL BRANDS OF TINTED WINDSHIELDS AMOUNT TO BETWEEN 9 AND 15 PERCENT AT VISIBILITY DISTANCES RANGING BETWEEN 1000 AND 200 FT. RESULTS AGREE FAIRLY WELL WITH THE DATA OF BLACKWELL AND WITH DATA OBTAINED EXPERIMENTALLY IN THE FIELD BY OTHER AUTHORS. THE ANALYSIS SHOW THAT THE LOSSES IN VISIBILITY DISTANCES ARE GREATER FOR TARGETS SO NEARLY MATCHED TO THE BACKGROUND THAT THEY MAY BE SEEN EVEN WITH CLEAR WINDSHIELDS ONLY AT SHORT DISTANCES. UNDER THESE CONDITIONS THE LOSSES MAY BE AS HIGH AS 30 TO 45 PERCENT. A RECONSIDERATION OF THE 70 PERCENT MINIMUM TRANSMITTANCE REQUIREMENT FOR WINDSHIELDS IN THE AMERICAN STANDARD SAFETY CODE Z26.1-1950 IS RECOMMENDED /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/127/127-005.pdf
• Supplemental Notes:
  • 12pp, 9 Fig, 3 TAB, 5 REF 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:
  • Haber, Heinz
• Publication Date: 1956

Media Info

• Media Type: Digital/other
• Pagination: 8p
• Monograph Title: Night visibility, 1955
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 127
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Absorption; Automobiles; Color; Distance; Heat; Night visibility; Visibility; Windshields
• Old TRIS Terms: Tints /materials/; Transmittance
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00223182
• Record Type: Publication
• Source Agency: Nat Safety Council Safety Res Info Serv
• Files: TRIS
• Created Date: Aug 26 1970 12:00AM