ELEMENTS OF ROADWAY LIGHTING

THE PURPOSE OF ANY ROADWAY LIGHTING SYSTEM IS TO ALLOW QUICK, ACCURATE AND COMFORTABLE VISION AT NIGHT. THERE ARE THREE GENERAL METHODS BY WHICH WE SEE AT NIGHT' SILHOUETTE, SURFACE DETAIL AND REVERSE SILHOUETTE. THESE METHODS OF DISCERNMENT ARE DEFINED AND DISCUSSED. OTHER FACTORS AFFECTING VISIBILITY INCLUDE THE SIZE OF AN OBJECT, THE TIME AVAILABLE FOR VIEWING, AND THE GLARE. THERE ARE TWO TYPES OF GLARE, VEILING GLARE AND DISCOMFORT GLARE. THE FORMER LIMITS OUR ABILITY TO SEE BUT WITHOUT CONSCIOUS AWARENESS, ON THE OTHER HAND, WE ARE READILY AWARE OF DISCOMFORT GLARE, SUCH AS THAT PRODUCED BY BRIGHT SUNLIGHT. VARIOUS LIGHT SOURCES ARE DESCRIBED SUCH AS INCANDESCENT AND GAS DISCHARGE LAMPS. THE INCANDESCENT LIGHT PRODUCES ILLUMINATION BY HEATING A COILED FILAMENT WIRE TO INCANDESCENCE. THE GAS DISCHARGE LAMPS PRODUCES ILLUMINATION BY THE PASSAGE OF AN ELECTRIC ARC THROUGH A GASEOUS MEDIUM, AS IN THE MERCURY LAMP, AND/OR THE ACTIVIATION OF PHOSPHORS AS IN THE FLUORESCENT LAMP. THE TERM LUMINAIRE IS DEFINED AS INCLUDING THE LAMP, SOCKET, A METAL HOUSING, GLASSWARE AND AUXILIARY EQUIPMENT AS NEEDED. DISTRIBUTION OF VARIOUS LAMP TYPES FOR SUCCESSFUL ILLUMINATION IS DISCUSSED.

• Supplemental Notes:
  • Vol 4, No 1, PP 10-14, 6 PHOT
• Authors:
  • Box, P C
• Publication Date: 1967-4

Media Info

• Serial:
  • Public Safety Systems

Subject/Index Terms

• TRT Terms: Fluorescent lamps; Glare; Incandescent lamps; Luminaires; Mercury vapor lamps; Night visibility; Night vision; Size; Street lighting; Time
• Old TRIS Terms: Mercury lamps
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00219918
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 14 1994 12:00AM