Contains: TI: AUTOMOBILE GLARE AND HIGHWAY VISIBILITY MEASUREMENTS. AU: Bone-EP SO: Highway Research Board Bulletin. 1951/03. NT: No 34, pp 3-20, 4 FIG, 3 REF, 1 APP PY: 1951 AB: 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/. TI: REFLEX REFLECTOR PERFORMANCE CRITERIA. AU: Finch-DM SO: Highway Research Board Bulletin. 1951/03. NT: No 34, pp 21-40, 20 FIG, 6 REF, 2 APP PY: 1951 AB: REFLEX REFLECTORS ARE SPECIAL TYPES OF MIRRORS WHICH HAVE THE CHARACTERISTIC OF RETURNING A SUBSTANTIAL FRACTION OF THE INCIDENT LIGHT TOWARD THE SOURCE FROM WHICH IT ORIGINATES REGARDLESS OF THE INCIDENT ANGLE. BECAUSE OF THEIR PECULIAR OPTICAL CHARACTERISTICS, REFLEX REFLECTORS APPEAR VERY MUCH BRIGHTER THAN EVEN THE BEST OF WHITE PAINTS WHEN ILLUMINATED UNDER SIMILAR CONDITIONS AND ARE THUS VERY USEFUL IN MARKING ROADWAY OBSTACLES. A REVIEW OF THE VISUAL METHODS OF APPRAISAL HAS BEEN PREPARED TOGETHER WITH TYPICAL DATA SHOWING THE VARIATIONS FOUND WHEN THE HUMAN EYE IS USED AS A MEASURING INSTRUMENT. A PHOTO-ELECTRIC PHOTOMETER IS DESCRIBED WHICH PERMITS THE PHYSICAL MEASUREMENT OF THE LIGHT FLUX FROM REFLEX REFLECTORS WHEN THEY ARE USED UNDER CONDITIONS WHICH APPROXIMATE FIELD USAGE. DATA ARE SHOWN FOR THE CHANGES IN SPECIFIC INTENSITY WHEN THE DIFFERENT TYPES OF REFLECTORS ARE USED UNDER VARYING CONDITIONS OF DIVERGENCE ANGLE, ENTRANCE ANGLE, ORIENTATION ANGLE, TEST DISTANCE, SIZE OF LIGHT SOURCE, SIZE OF REFLECTOR, SIZE OF RECEIVER AND COLOR OF LIGHT SOURCE. A RECOMMENDED TEST PROCEDURE BASED UPON STANDARDIZED CONDITIONS IS OUTLINED. /AUTHOR/. AN ACRYLIC REFLECTING MATERIAL WHICH OFFERS NEW AND UNIQUE APPLICATIONS FOR TRAFFIC SIGNS / B.F. Hibbert (see A 3585) - AUTOMOBILE GLARE AND HIGHWAY VISIBILITY MEASUREMENTS / E.P. Bone - DISCUSSION Dr. A. B. Lauer, R. P. Teele, E.P. Bone - REFLEX REFLECTOR PERFORMANCE CRITERIA / D.H. Finch - PHOTOMETRIC TESTS FOR REFLECTIVE MATERIALS / B.W. Pocock and C. C. Rhodes.
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