AUTOMOBILE GLARE AND HIGHWAY VISIBILITY MEASUREMENTS
MEASUREMENTS INDICATE THAT HEADLIGHT GLARE IS MORE OF A HINDERANCE TO FULL HIGHWAY VISIBILITY THAN PREVIOUSLY RECOGNIZED. BECAUSE OF THE CHANGEABLENESS OF EYE SENSITIVITY, THE INADEQUACY OF MEETING VISIBILITY CAN ESCAPE DETECTION UNLESS THERE IS A STANDARD OF MEASURE. TESTS WERE CONDUCTED TO MEASURE SEPARATELY THE ADAPTATION LEVEL OF THE EYES WHEN EXPOSED TO THE ROADWAY ILLUMINATED BY SEALED BEAM (UP BEAM) HEADLIGHTS AND THEN WHEN EXPOSED TO THE GLARE OF VARIOUS CANDLE POWERS. A CANDLE POWER VALUE OF THE GLARE SOURCE WAS FOUND WHICH CAUSES THE SAME ADAPTATION LEVEL AS DOES THE HEADLIGHTED ROADWAY. COMPUTATIONS INDICATE THAT MEETING VISIBILITY UP TO 80 PERCENT OF OPEN ROAD VISIBILITY CAN BE ATTAINED IF THE OPPOSING GLARE IS NOT MORE THAN 20 CANDLE POWER. BY COMPARISON, THE GLARE FROM PRESENT HEADLIGHTS MAY REACH 800 TO 1,000 CANDLE POWER EVEN WITH THE BEAMS TILTED DOWN. THE MEASUREMENTS OF VISIBILITY REPORTED ARE BASED ON THE PREMISE THAT THE DRIVER NEEDS TO SEE AS WELL WHEN MEETING OTHER CARS AS WHEN DRIVING ALONE IN THE OPEN ROAD. IT IS CONCLUDED THAT RESEARCH TOWARDS SAFE HEADLIGHTING IS INDICATED. /AUTHOR/
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Supplemental Notes:
- 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
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Authors:
- Bone, E P
- Bone, Evan P
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Discussers:
- Lauer, A B
- Teele, B P
- Bone, Evan P
- Publication Date: 1951
Media Info
- Media Type: Print
- Pagination: pp 3-20
- Monograph Title: Reflectors and night visibility
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Serial:
- Highway Research Board Bulletin
- Issue Number: 34
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Drivers; Eye; Glare; Headlamps; Highways; Luminous intensity; Measurement; Psychological adaptation; Visibility; Vision
- Old TRIS Terms: Driver vision
- Subject Areas: Highways; Safety and Human Factors;
Filing Info
- Accession Number: 00220332
- Record Type: Publication
- Files: TRIS, TRB, ATRI
- Created Date: Apr 21 1994 12:00AM