00225351

Component

http://onlinepubs.trb.org...rbbulletin/255/255-012.pdf

PREVIOUS INVESTIGATIONS OF THE VISUAL CHARACTERISTICS OF FLASHING LIGHT SOURCES, FOR THE MOST PART, HAVE BEEN MADE AT LOW-ENERGY LEVELS AT OR NEAR A VISUAL THRESHOLD BY MEANS OF EXTENDED SOURCES. ALTHOUGH THE RESULTS OF THESE INVESTIGATIONS HAVE PROVED USEFUL, THEY ARE NOT DIRECTLY APPLICABLE TO THE DESIGN OF PORTABLE BATTERY-OPERATED WARNING LIGHTS WHERE CONDITIONS ARE SOMEWHAT DIFFERENT. THESE DIVICES ARE USUALLY FIRST SEEN AS NEARBY POINT SOURCES UNDER SUPRATHRESHOLD CONDITIONS. NEW DATA HAVE BEEN DEVELOPED WHICH RELATE TO THE IMPORTANT PHYSICAL CHARACTERISTICS, SUCH AS FLASH DURATION AND WAVE FORM, THAT DIRECTLY AFFECT THE PERCEPTUAL CLUES PROVIDED BY SUCH WARNING DEVICES. THE EFFECT OF DURATION AND WAVE FORM ON THE EFFECTIVE INTENSITY OF POINT SOURCES OF FLASH ENERGIES OF 0.1 CANDLEPOWER-SECONDS (RED LIGHT) HAS BEEN INVESTIGATED BY PERFORMING INTENSITY MATCHES BETWEEN TWO MODULATED SOURCES, ONE OF WHICH HAS A FIXED DURATION AND PEAK INTENSITY. AT THIS FLASH ENERGY, WHICH WAS CHOSEN AS BEING SIGNIFICANTLY ABOVE A VISUAL THRESHOLD FOR A DARK-ADAPTED EYE AND AS BEING READILY OBTAINABLE BY CURRENTLY MANUFACTURED DEVICES, FLASHES THAT HAVE DURATIONS LONGER THAN 50 MILLISECONDS REQUIRE MORE ENERGY TO HAVE AN EQUAL VISUAL EFFECT THAN FLASHES OF SHORTER DURATION. THIS RESULT IS HIGHLY IMPORTANT TO THE CONSERVATION OF BATTERY ENERGY. OTHER FACTORS THAT INFLUENCE THE DESIGN OF BATTERY-OPERATED UNITS (FOR EXAMPLE, FLASH RATE, FLASH ENERGY, AND PLACEMENT OF UNITS) ARE DISCUSSED. /AUTHOR/

No 255, pp 146-157, 6 FIG, 4 TAB, 27 REF 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.

01408844

1960

Highway Research Board Bulletin

Dark adaptation; Electric batteries; Flashing; Time; Visibility; Visual perception; Warning systems; Waveform analysis

Energy; Highways; Operations and Traffic Management; Safety and Human Factors

TRIS, TRB

Sep 12 1994 12:00AM

• ADVANCEMENT IN ROADWAY LIGHTING
• AN EXPERIMENTAL LOW-COST LIGHTING SYSTEM FOR IMPORTANT HIGHWAYS IN RURAL AREAS
• DARK ADAPTATION AS A FUNCTION OF AGE AND TINTED WINDSHIELD GLASS
• DRIVER PERFORMANCE RELATED TO INTERCHANGE MARKING AND NIGHTTIME VISIBILITY CONDITIONS
• EFFECTIVENESS OF HOLLAND TUNNEL TRANSITIONAL LIGHTING DURING THE WINTER MONTHS
• ILLUMINATION REQUIREMENTS FOR ROADWAY VISUAL TASKS
• INFLUENCE OF TINTED WINDSHIELD GLASS ON FIVE VISUAL FUNCTIONS
• SOME FACTORS AFFECTING DRIVER EFFICIENCY AT NIGHT
• SOME RESULTS OF COOPERATIVE VEHICLE LIGHTING RESEARCH
• THE ASSOCIATION BETWEEN RETINAL SENSITIVITY AND THE GLARE PROBLEM
• TRAFFIC OPERATIONS AS RELATED TO HIGHWAY ILLUMINATION AND DELINEATION
• UNIFIED REFLECTIVE SIGN, PAVEMENT AND DELINEATION TREATMENTS FOR NIGHT TRAFFIC GUIDANCE
• VISION AT LEVELS OF NIGHT ROAD ILLUMINATION V. LITERATURE 1959
• VISUAL COMFORT EVALUATIONS OF ROADWAY LIGHTING