BRIGHTER NOT NECESSARILY BETTER IN TRAFFIC SIGNALS

FAULTY VISION ACCOUNTS FOR ABOUT 12% OF TRAFFIC ACCIDENTS, AND EXCESSIVE GLARE EXPOSURE IS ONE OF THE CONTRIBUTING FACTORS. GLARE AT NIGHT IS USUALLY ASSOCIATED WITH ONCOMING HEADLIGHTS. THIS IS AN EXAMPLE OF "DISABILITY GLARE," WHEN THE LIGHT RECEPTORS ---RODS AND CONES---IN THE RETINA CANNOT ACCEPT ALL THE TRANSMITTED LIGHT. HOWEVER, THERE IS ALSO A "DISCOMFORT GLARE" THAT MAY NOT REDUCE THE VISIBILITY OF WHAT IS BEING SEEN BUT ALTERS THE DRIVER'S WILLINGNESS TO VIEW IT. THIS MAY BE THE CASE WITH EXCESSIVELY BRIGHT TRAFFIC SIGNALS, WHEN THE CONTRAST BETWEEN THE IMAGE AND ITS BACKGROUND IS REDUCED TO A POINT THAT THE DRIVER IS UNWILLING TO ACCEPT. THE CONDITION IS EXACERBATED BY A DECREASE IN LENS SIZE AT A CONSTANT BRIGHTNESS, SINCE PERCEIVED BRIGHTNESS INCREASES INVERSELY AS THE SQUARE OF THE DIFFERENCE IN DIAMETER. THERE ARE SEVERAL MEANS OF ADJUSTING INTENSITY TO AMBIENT LIGHT CONDITIONS. THREE TYPES OF DEVICES ARE DISCUSSED.

• Authors:
  • Leiser, C F
• Publication Date: 1972-12

Media Info

• Features: Figures;
• Pagination: p. 15-6
• Serial:
  • IMSA Signal Magazine
  • Volume: 8
  • Issue Number: 6
  • Publisher: International Municipal Signal Association

Subject/Index Terms

• TRT Terms: Brightness; Diameter; Drivers; Eye; Glare; Lenses (Geology); Reaction time; Size; Traffic signals; Vision
• Uncontrolled Terms: Driver reaction
• Old TRIS Terms: Driver vision; Lenses (Excluding soils)
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00222095
• Record Type: Publication
• Files: TRIS
• Created Date: May 7 1973 12:00AM