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Volume XV
Enhanced Night Visibility Series: Phase III – Study 3: Influence of Beam Characteristics on Discomfort and Disability Glare
December 2005
FHWA-HRT-04-146
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U.S. Department of Transportation
Federal Highway Administration
Research, Development, and Technology
Turner–Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101–2296
FOREWORD
The overall goal of the Federal Highway Administration’s (FHWA) Visibility Research Program is to enhance the safety of road users through near-term improvements of the visibility on and along the roadway. The program also promotes the advancement of new practices and technologies to improve visibility on a cost-effective basis.
The following document summarizes the results of a study evaluating the influence of headlamp beam characteristics on discomfort and disability glare from various headlamp systems. The study was conducted under Phase III of the Enhanced Night Visibility (ENV) project, a comprehensive evaluation of evolving and proposed headlamp technologies in various weather conditions. The individual studies within the overall project are documented in an 18-volume series of FHWA reports, of which this is Volume XV. It is anticipated that the reader will select those volumes that provide information of specific interest.
This report will be of interest to headlamp designers, automobile manufacturers and consumers, third-party headlamp manufacturers, human factors engineers, and people involved in headlamp and roadway specifications.
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Michael F. Trentacoste Director, Office of Safety Research and Development |
Notice
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.
Quality Assurance Statement
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
TECHNICAL REPORT DOCUMENTATION PAGE
1. Report No. FHWA-HRT-04-146 |
2. Government Accession No. |
3. Recipient’s Catalog No. |
4. Title and Subtitle Enhanced Night Visibility Series, Volume XV:
Phase III—Study 3: Influence of Beam Characteristics on Discomfort and Disability Glare
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5. Report Date December 2005 |
6. Performing Organization Code
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7. Author(s)
Jason Clark, Ronald B. Gibbons, and Jonathan M. Hankey |
8. Performing Organization Report No. |
9. Performing Organization Name and Address
Virginia Tech Transportation Institute
3500 Transportation Research Plaza
Blacksburg, VA 24061 |
10. Work Unit No.
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11. Contract or Grant No.
DTFH61-98-C-00049 |
12. Sponsoring Agency
Name and Address
Office of Safety Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101-2296
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13.Type of Report and Period Covered
Final Report |
14. Sponsoring Agency Code HRDS-05 |
15. Supplementary Notes
Contracting Officer’s Technical Representative (COTR): Carl Andersen, HRDS-05
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16. Abstract
The objective of this study was to evaluate the discomfort and disability glare produced by oncoming headlamps with varying beam intensity and distribution. Oncoming headlamps can be visually discomforting and disabling to drivers at night. In recent years, high intensity discharge (HID) headlamps have raised some concern because of their increased light output and brighter appearance than traditional halogen headlamps.
During the discomfort glare portion of this study, participants drove an experimental vehicle at 32 km/h (20 mi/h) past stationary glare headlamps. They were asked to rate their overall discomfort using the subjective deBoer scale. The disability glare portion involved drivers detecting a static pedestrian either near the road centerline or near the road edgeline while approaching different sets of glare headlamps. It was hypothesized that there would be significant differences in detection distance, illuminance at the driver’s eye, and discomfort glare rating across the different glare headlamp, pedestrian position, adaptation level, and participant age combinations.
The main effect of glare headlamp was the only significant factor in the analysis for discomfort glare. The main effects of age, glare headlamp, and pedestrian location were all significant in the analysis for the disability glare portion. In addition, the interaction of pedestrian location and glare headlamp was significant. Overall, headlamps that had higher subjective discomfort ratings were the same lamps that had worse objective disability measures.
The conclusions of this research will be valuable to the consumer as well as the manufacturers and designers of future headlamps in revealing how glare can affect drivers on the road at night. This information can help guide new designs to maximize forward visibility while minimizing glare.
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17. Key Words
deBoer, Detection, Disability Glare, Discomfort Glare, Halogen, High Intensity Discharge, Illuminance, Pedestrian
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18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
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19. Security Classif. (of this report)
Unclassified
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20. Security Classif. (of this page)
Unclassified
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21. No. of Pages 119 |
22. Price |
Form DOT F 1700.7 (8-72) Reproduction of completed page authorized
ENHANCED NIGHT VISIBILITY PROJECT REPORT SERIES
This volume is the 15th of 18 volumes in this research report series. Each volume is a different study or summary, and any reference to a report volume in this series will be referenced in the text as “ENV Volume I,” “ENV Volume II,” and so forth. A list of the report volumes follows:
Volume |
Title |
Report Number |
I |
Enhanced Night Visibility Series: Executive Summary |
FHWA-HRT-04-132 |
II |
Enhanced Night Visibility Series: Overview of Phase I and Development of Phase II Experimental Plan |
FHWA-HRT-04-133 |
III |
Enhanced Night Visibility Series: Phase II—Study 1: Visual Performance During Nighttime Driving in Clear Weather |
FHWA-HRT-04-134 |
IV |
Enhanced Night Visibility Series: Phase II—Study 2: Visual Performance During Nighttime Driving in Rain |
FHWA-HRT-04-135 |
V |
Enhanced Night Visibility Series: Phase II—Study 3: Visual Performance During Nighttime Driving in Snow |
FHWA-HRT-04-136 |
VI |
Enhanced Night Visibility Series: Phase II—Study 4: Visual Performance During Nighttime Driving in Fog |
FHWA-HRT-04-137 |
VII |
Enhanced Night Visibility Series: Phase II—Study 5: Evaluation of Discomfort Glare During Nighttime Driving in Clear Weather |
FHWA-HRT-04-138 |
VIII |
Enhanced Night Visibility Series: Phase II—Study 6: Detection of Pavement Markings During Nighttime Driving in Clear Weather |
FHWA-HRT-04-139 |
IX |
Enhanced Night Visibility Series: Phase II—Characterization of Experimental Objects |
FHWA-HRT-04-140 |
X |
Enhanced Night Visibility Series: Phase II—Visual Performance Simulation Software for Objects and Traffic Control Devices |
FHWA-HRT-04-141 |
XI |
Enhanced Night Visibility Series: Phase II—Cost-Benefit Analysis |
FHWA-HRT-04-142 |
XII |
Enhanced Night Visibility Series: Overview of Phase II and Development of Phase III Experimental Plan |
FHWA-HRT-04-143 |
XIII |
Enhanced Night Visibility Series: Phase III—Study 1: Comparison of Near Infrared, Far Infrared, High Intensity Discharge, and Halogen Headlamps on Object Detection in Nighttime Clear Weather |
FHWA-HRT-04-144 |
XIV |
Enhanced Night Visibility Series: Phase III—Study 2: Comparison of Near Infrared, Far Infrared, and Halogen Headlamps on Object Detection in Nighttime Rain |
FHWA-HRT-04-145 |
XV |
Enhanced Night Visibility Series: Phase III—Study 3: Influence of Beam Characteristics on Discomfort and Disability Glare |
FHWA-HRT-04-146 |
XVI |
Enhanced Night Visibility Series: Phase III—Characterization of Experimental Objects |
FHWA-HRT-04-147 |
XVII |
Enhanced Night Visibility Series: Phases II and III— Characterization of Experimental Vision Enhancement Systems |
FHWA-HRT-04-148 |
XVIII |
Enhanced Night Visibility Series: Overview of Phase III |
FHWA-HRT-04-149 |
TABLE OF CONTENTS
CHAPTER 1—INTRODUCTION
CHAPTER 2—METHODS
CHAPTER 3—RESULTS
CHAPTER 4—DISCUSSION
CHAPTER 5—SUMMARY
APPENDIX A—SCREENING QUESTIONNAIRE
APPENDIX B—INFORMED CONSENT FORM
APPENDIX C—VISION TEST FORM
APPENDIX D—IN-VEHICLE EXPERIMENTAL PROTOCOL
APPENDIX E—ONROAD EXPERIMENTAL PROTOCOL
APPENDIX F—AIMING PROTOCOL
APPENDIX G—VES CHARACTERISTICS
APPENDIX H—PREDRIVE QUESTIONNAIRE
APPENDIX I—RESULTS ANOVA TABLES
APPENDIX J—RESULTS FOR ANOVA WITHOUT THE LOW/WIDE VES
REFERENCES
LIST OF FIGURES
- Line graph. Spectral power distribution of typical HID and halogen headlamps.
- Line graph. Illuminance readings taken on a divided highway at night with and without overhead lighting and glare.
- Photo. Light source used to control driver light adaptation level.
- Photo. Brightness Acuity Tester.
- Photo. Back view of glare cart with halogen VESs (low/narrow) mounted.
- Photo. Glare cart and experimental vehicle on the Smart Road.
- Photo. Glare cart with VESs at night with left pedestrian.
- Diagram. Plan view of the participant vehicle at the start point in the discomfort glare portion.
- Diagram. Plan view of the participant vehicle at the start point for the disability glare portion with right pedestrian.
- Bar graph. deBoer discomfort ratings for the main effect of VES (scale of 1 to 9).
- Bar graph. Mean detection distances for the interaction of pedestrian and VES.
- Bar graph. Mean detection distances for the main effect of VES with SNK groupings.
- Bar graph. Mean detection distances for the main effect of age group with SNK groupings.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the Pedestrian by VES by Age interaction.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the VES by Age interaction.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the Pedestrian by Age interaction.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the Pedestrian by VES interaction.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the main effect of VES with SNK groupings.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the main effect of age group with SNK grouping.
- Bar graph. BAT results by age group.
- Line graph. The relationship between headlamp intensity and perceived glare.
- Photo. Front view of HID 1 headlamp (high/narrow).
- Photo. Front view of HID 2 headlamp (high/wide).
- Photo. Front view of HID 3 headlamp (medium/medium).
- Photo. Front view of HID 4 headlamp (low/wide).
- Photo. Front view of halogen headlamp (low/narrow).
- Bar graph. Secondary analysis mean detection distances for the interaction of pedestrian and VES.
- Bar graph. Mean illuminance readings (lx) at moment of detection for the Pedestrian by VES interaction without the low/wide VES.
LIST OF TABLES
- Factors for the experimental design: 5 (VESs) by 3 (age) mixed factor design.
- Two pedestrian locations and two adaptation levels corresponding to each cell in table 1.
- Available VESs categorized by width (degrees) and intensity (candela).
- VES characteristic matrix.
- Object descriptions.
- Typical results of normal glare sensitivity with BAT.
- Typical results of mild glare sensitivity with BAT.
- Typical results of severe glare sensitivity with BAT.
- Mixed-factor design for discomfort glare.
- Mixed-factor design for detection distance and illuminance.
- Significant main effects and interactions.
- Discomfort glare SNK groupings for the VES main effect.
- Detection distance SNK groupings for the VES main effect.
- Illuminance SNK groupings for the VES main effect.
- ANOVA table for discomfort glare results.
- ANOVA table for the objective measurement of disability glare with detection distances.
- ANOVA table for the objective measurement of driver’s eye illuminance.
- Secondary analysis ANOVA significant main effects and interactions.
- Secondary analysis ANOVA table for discomfort glare rating.
- Discomfort glare SNK groupings comparison for the VES main effect.
- Secondary analysis ANOVA table for detection distances.
- Detection distance SNK groupings comparison for the VES main effect.
- Detection distance SNK groupings comparison for the age main effect.
- Secondary analysis ANOVA table for the objective measurement of driver’s eye illuminance.
- Illuminance SNK groupings comparison for the VES main effect.
- Illuminance SNK groupings comparison for the age main effect.
LIST OF ACRONYMS AND ABBREVIATIONS
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