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Publication Number: FHWA-HRT-04-137
Date: December 2005

Enhanced Night Visibility Series, Volume VI: Phase II—Study 4: Visual Performance During Nighttime Driving in Fog

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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 on the visual performance of drivers during nighttime driving in fog. The study was conducted under Phase II of the Enhanced Night Visibility (ENV) project, a comprehensive evaluation of evolving and proposed headlamp technologies under 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 VI. 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.

 

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-04-137

2. Government Accession No.

3. Recipient’s Catalog No.

4. Title and Subtitle
Enhanced Night Visibility Series, Volume VI: Phase II—Study 4: Visual Performance During Nighttime Driving in Fog

5. Report Date
December 2005

6. Performing Organization Code

7. Author(s)
Myra Blanco 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.

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

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

16. Abstract
Phase II—Study 4 was part of the Enhanced Night Visibility project, a larger research effort investigating drivers’ visual performance during nighttime driving. Study 4 helped expand the knowledge of how current vision enhancement systems can affect detection and recognition of different types of objects during adverse weather, specifically for fog conditions. Thirty participants were involved in the study. A 6 by 3 mixed factorial design was used to investigate the effects of different types of vision enhancement systems and driver’s age on detection and recognition of a pedestrian on the roadway. Subjective evaluations also were obtained for the different vision enhancement systems.

The analysis based on objective and subjective results revealed that the infrared thermal imaging system is the best configuration for detecting pedestrians in fog conditions. Halogen headlamps supplemented with ultraviolet A (UV–A) was a better configuration for detecting pedestrians than the halogen and high intensity discharge (HID) headlamps alone; however, the UV–A technology does not represent a dramatic improvement over the halogen and HID headlamps used in this research.

17. Key Words
Age, Detection, Fog, Halogen, Headlamp, High Intensity Discharge (HID), Infrared, Night Vision, Nighttime, Pedestrian, Recognition, Ultraviolet, Vision Enhancement System, Weather

18. Distribution Statement
No restrictions. This document is available through the National Technical Information Service; Springfield, VA 22161.

19. Security Classif. (of this report)
Unclassified

20. Security Classif. (of this page)
Unclassified

21. No. of Pages
111

22. Price

Form DOT F 1700.7 (8-72)          Reproduction of completed page authorized


SI* (Modern Metric) Conversion Factors


ENHANCED NIGHT VISIBILITY PROJECT REPORT SERIES

This volume is the sixth 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 AND CONCLUSIONS

APPENDIX A—SCREENING QUESTIONNAIRE

APPENDIX B—INFORMED CONSENT FORM

APPENDIX C—VISION TEST FORM

APPENDIX D—TRAINING PROTOCOL

APPENDIX E—TRAINING SLIDES

APPENDIX F—FRONT SEAT EXPERIMENTER’S PROTOCOL

APPENDIX G—BACK SEAT EXPERIMENTER’S PROTOCOL

APPENDIX H—SMART ROAD

APPENDIX I—DEBRIEFING FORM

APPENDIX J—ONROAD EXPERIMENTER’S PROTOCOL

APPENDIX K—AIMING PROTOCOL

APPENDIX L—VALET PROTOCOL

REFERENCES

LIST OF FIGURES

  1. Photo. Perpendicular pedestrian in white clothing.
  2. Diagram. Data collection display screen.
  3. Photo. Five UV–A + HLB.
  4. Photo. Hybrid UV–A + HLB.
  5. Photo. HID.
  6. Photo. HLB–LP with IR–TIS.
  7. Photo. Smart Road.
  8. Diagram. Locations where pedestrians were presented for the adverse weather condition (note the area where fog was generated).
  9. Diagram. Fog tower generating fog.
  10. Photo. Smart Road overhead lighting system and fog towers starting to make fog.
  11. Bar graph. Bonferroni post hoc results for the main effect: VES.
  12. Bar graph. Bonferroni post hoc results for the main effect: age.
  13. Bar graph. Bonferroni post hoc results on the ratings evaluating detection for the main effect: VES.
  14. Bar graph. Bonferroni post hoc results on the ratings evaluating recognition for the main effect: VES.
  15. Bar graph. Bonferroni post hoc results on the overall rating for the main effect: VES.
  16. Scatter plot. Young drivers’ detection versus recognition distances.
  17. Scatter plot. Middle-aged drivers’ detection versus recognition distances.
  18. Scatter plot. Older drivers’ detection versus recognition distances.
  19. Bar graph. Participants’ visual acuity divided by age group.
  20. Bar graph. Participants’ contrast sensitivity at 1.5 cpd (cycles per degree) divided by age group.
  21. Bar graph. Participants’ contrast sensitivity at 3.0 cpd divided by age group.
  22. Bar graph. Participants’ contrast sensitivity at 6.0 cpd divided by age group.
  23. Bar graph. Participants’ contrast sensitivity at 12.0 cpd divided by age group.
  24. Bar graph. Participants’ contrast sensitivity at 18.0 cpd divided by age group.
  25. Equation. Braking distance.
  26. Equation. Total stopping distance for brake reaction time plus braking distance.
  27. Equation. AASHTO calculation of coefficient of friction for wet pavement.
  28. Photo. Smart Road testing facility.

LIST OF TABLES

  1. Experimental design: 6 by 3 mixed-factor design (6 VES configurations, 3 age groups).
  2. Description of the object.
  3. Example of the VES configuration order for a pair of participants.
  4. Model for the experimental design.
  5. Backscatter from fog by VES.
  6. ANOVA summary table for the dependent measurement: detection distance.
  7. ANOVA summary table for the dependent measurement: recognition distance.
  8. Summary of significant main effects and interactions.
  9. ANOVA summary table for the Likert-type rating for detection.
  10. ANOVA summary table for the Likert-type rating for recognition.
  11. ANOVA summary table for the Likert-type rating for lane-keeping assistance.
  12. ANOVA summary table for the Likert-type rating for roadway direction.
  13. ANOVA summary table for the Likert-type rating for visual discomfort.
  14. ANOVA summary table for the Likert-type rating for overall safety rating.
  15. ANOVA summary table for the Likert-type rating for overall VES evaluation.
  16. Summary of significant main effects and interactions for the Likert-type rating scales.
  17. Differences in detection distances between clear, rain, and snow conditions and the fog condition.
  18. Mean detection and recognition distances during nighttime driving in fog.
  19. Difference in reaction time available depending on vehicle speed; based on the difference of detection time from HLB.
  20. Stopping distances needed for a dry roadway.
  21. Detection distances of white-clothed perpendicular pedestrian and potential detection inadequacy when compared to stopping distance at various speeds.

LIST OF ACRONYMS AND ABBREVIATIONS

 

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