REQUIREMENTS FOR AUTOMOBILE EXTERIOR LIGHTING

THE ILLUMINATION OF THE ROADWAY AHEAD PROVIDED BY AN AUTOMOBILE HEADLAMP IS NOW RESTRICTED BY A 15,000 CANADLEPOWER LIMITATION, WHICH IS MUCH TOO LOW. IF THE SHAPE AND DIRECTION OF THE HEADLAMP BEAM WERE BETTER CONTROLLED, AS HIGH AS 40,000 CANDLEPOWER MIGHT BE POSSIBLE WITHOUT HAZARD TO APPROACHING DRIVERS, AND THIS WOULD PROVIDE MUCH IMPROVED VISIBILITY. IN MANY AREAS OF EUROPE, IT IS CUSTOMARY TO DRIVE ON ILLUMINATED STREETS AT NIGHT WITH ONLY PARKING LIGHTS. IF STREETS WERE ADEQUATELY ILLUMINATED, THIS MIGHT BE AN EXCELLENT SYSTEM, BUT IN MANY INSTANCES ILLUMINATION IS FAR FROM ADEQUATE AND THE PRACTICE DANGEROUS. ON THE VALUE OF AUTOMOBILE EXTERIOR LIGHTS AS SIGNALING SYSTEMS FOR OTHER MOTORISTS, A SINGLE SET OF REAR LIGHT FIXTURES MAY BE USED TO INDICATE THE PRESENCE OF AN AUTOMOBILE; WHEN THEY ARE ILLUMINATED AT NIGHT, THEY MAY BE USED TO SIGNAL APPLICATION OF BRAKES BY ILLUMINATION OF ADDITIONAL BULBS FOR INCREASED INTENSITY, AND THEY MAY BE USED TO SIGNAL TURNING BY FLASHING ILLUMINATION OF THE FIXTURE ON ONE SIDE OR THE OTHER. THESE LAMPS ALSO PROVIDE DISTANCE INFORMATION BECAUSE THERE ARE TWO LIGHTS WITH A REASONABLY CONSTANT LATERAL SEPARATION. THE VISUAL ANGLE SUBTENDED BY THE SEPARATION IS THUS A CUE TO THE DISTANCE OF THE VEHICLE. FOR TRUCKS, REAR LIGHTS EXTENDED IN AN ARRAY ALONG THE TWO SIDES OR SUPPLEMENTED BY AN ADDITIONAL LIGHT AT THE TOP OF THE TRUCK PROVIDE SOME INFORMATION AS TO THE NATURE OF THE VEHICLE. SEPARATE FIXTURES FOR STOPPING AND TURNING HAVE BEEN DEMONSTRATED TO SPEED THE REACTION TIME OF A FOLLOWING DRIVER IN RESPONSE TO SUCH SIGNALS. AUTOMOBILES ARE DRIVEN UNDER A WIDE RANGE OF CONDITIONS, AND, UNLESS SUCH FACTORS AS THE NATURE OF THE TRAFFIC, TYPE OF ROAD, AND AMOUNT OF CONGESTION ARE TAKEN INTO ACCOUNT, COMPARISONS BASED SOLELY ON TIME AT THE WHEEL MAY BE IRRELEVANT. THERE HAS PERHAPS BEEN TOO MUCH CONCERN WITH THE PROBLEM OF GLARE AND INSUFFICIENT ATTENTION PAID TO WAYS IN WHICH VISIBILITY MAY BE INCREASED AND BENEFITS BE DERIVED THEREFROM WITH A MINIMUM OF INCREASE IN GLARE. /AUTHOR/

• Supplemental Notes:
  • pp 30-51, 15 FIG, 3 TAB, REF
• Corporate Authors:

  National Academy Sciences

  /Committee On Vision
  ,   United States 
• Authors:
  • Mortimer, R G
• Publication Date: 1969

Subject/Index Terms

• TRT Terms: Brake lamps; Color codes; Drivers; Headlamps; Street lighting; Taillamps; Turn signals; Vehicle lighting; Vision
• Old TRIS Terms: Braking lights; Driver vision; Turning lights
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00223513
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 2 1971 12:00AM