ROADSIDE SIGN VISIBILITY

SIGN VISIBILITY MEASUREMENTS ARE PRESENTED AS THEY ARE EFFECTED BY LUMINAIRE MOUNTING HEIGHT, AND LATERAL POSITION. THE LUMINAIRES WERE MOUNTED ON SEVEN PORTABLE TOWERS TO REPRESENT A ONE-SIDE LIGHTING SYSTEM, USING 400-WATT MERCURY LUMINAIRES. MOUNTING HEIGHTS OF 30 AND 40 FEET WERE STUDIED FOR COMPARISON PURPOSES. THE SIGN SELECTED FOR THIS STUDY WAS A TYPICAL DESTINATION SIGN WITH BLACK PAINTED LETTERS ON A REFLECTORIZED WHITE BACKGROUND. THE FOLLOWING CONCLUSIONS WERE REACHED' /1/ THE 40 FOOT MOUNTING HEIGHT OF LUMINAIRES IMPROVES THE DISTRIBUTION OF LIGHT IN A CONTINUOUS ILLUMINATION SYSTEM. /2/ THE 40-FT. MOUNTING HEIGHT PROVIDES AN INCREASE IN LEGIBILITY DISTANCE OF APPROXIMATELY 12 PERCENT. /3/ THE EFFECT OF HEADLIGHT CONDITION ON SIGN LEGIBILITY IS LESS FOR 40-FOOT MOUNTING HEIGHT THAN FOR 30- FOOT MOUNTING HEIGHT. /4/ FOR BEST LEGIBILITY ROADSIDE SIGNS SHOULD BE PLACED DIRECTLY IN LINE WITH THE LUMINAIRES AT A LONGITUDINAL POSITION OF 20 TO 60 FEET BEYOND THE LUMINAIRE AS VIEWED BY THE DRIVER SINCE THE LONGITUDINAL POSITION IS NOT CRITICAL FOR THE 40-FOOT MOUNTING HEIGHT. /5/ THE 40- FOOT MOUNTING HEIGHT RESULTS IN A SYSTEM OF LOWER SIGN BRIGHTNESS AND DISABILITY VEILING BRIGHTNESS LEVELS AND /6/ LEGIBILITY AND ROADSIDE SIGNS CAN BE RELATED TO BRIGHTNESS CONTRAST AND GLARE. /BPR/

• Supplemental Notes:
  • Hpr, 75-3, STATE 2-8-64-75
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas State Department of Highways & Public Transp

  11th and Brazos Streets
  Austin, TX  United States  78701
• Authors:
  • Walton, N E
  • Rowan, N J
• Publication Date: 1966-12-13

Subject/Index Terms

• TRT Terms: Brightness; Glare; Height; Legibility; Luminaires; Measurement; Mercury vapor lamps; Origin and destination; Reflectorized materials; Towers; Traffic signs; Visibility
• Old TRIS Terms: Mercury lamps; Mounting; Reflectorization
• Subject Areas: Highways; Operations and Traffic Management; Safety and Human Factors;

Filing Info

• Accession Number: 00219674
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS, STATEDOT
• Created Date: Feb 1 1994 12:00AM