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Publication Number: FHWA-HRT-04-140
Date: December 2005

Enhanced Night Visibility Series, Volume IX: Phase II—Characterization of Experimental Objects

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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 provides a characterization of the experimental objects used in the evaluation of the visual performance of drivers during nighttime driving in various weather conditions. The experimental objects were used in the Phase II efforts of the Enhanced Night Visibility (ENV) project, a comprehensive evaluation of evolving and proposed headlamp technologies. The individual studies within the overall project are documented in an 18-volume series of FHWA reports, of which this is Volume IX. 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-04-140

2. Government Accession No. 3 Recipient's Catalog No.
4. Title and Subtitle

Enhanced Night Visibility Series, Volume IX: Phase II—Characterization of Experimental Objects

5. Report Date

December 2005

6. Performing Organization Code
7. Author(s)

Ronald B. Gibbons, 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. (TRAIS)

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

The Enhanced Night Visibility (ENV) project is a series of experiments undertaken to investigate different visual enhancement systems (VES) for the nighttime driving task. The purpose of this portion of the ENV project is to establish the photometric nature of the objects presented to the observer. The photometric measurements of interest are the headlamp illuminance, object luminance, and the background luminance. Other calculated parameters were established such as object contrast with the background, reflectance of the objects, and object visibility level. The measurements were taken and calculated for 11 VESs and 8 object types.

The correlation of the measurement results to those of the ENV visual performance studies was calculated. It was found that all the calculated metrics were fairly highly correlated to the participant results. The visibility level was the least correlated, and the Weber contrast ratio was the most highly correlated.

The transmittance of the atmosphere was also calculated for each of the weather conditions used in the ENV visual performance studies. The correlations calculated for these conditions showed that the Weber contrast was again the most highly correlated metric.

17. Key Words

Halogen, Headlamps, High Intensity Discharge, Liquid System, Nighttime, Photometry, Luminance, Contrast, Visibility Level, Ultraviolet, Visibility, Vision Enhancement System

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.

19. Security Classification
(of this report)

Unclassified

20. Security Classification
(of this page)

Unclassified

21. No. of Pages

113

22. Price
Form DOT F 1700.7 Reproduction of completed page authorized

SI* (Modern Metric) Conversion Factors

ENHANCED NIGHT VISIBILITY PROJECT REPORT SERIES

This volume is the ninth 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—EFFECT OF ADVERSE WEATHER

REFERENCES

LIST OF FIGURES

  1. Diagram. Object stations (locations) on the Virginia Smart Road.
  2. Illustration. Parallel pedestrian measurement points.
  3. Illustration. Perpendicular pedestrian measurement points.
  4. Illustration. Cyclist measurement points.
  5. Illustration. Child’s bicycle measurement points.
  6. Illustration. Tire tread measurement points.
  7. Bar graph. Comparison of the mean of background object luminance for HLB combined with different UV–A levels when the photometer operator is in the back seat or the driver’s seat.
  8. Bar graph. Comparison of object luminance for HLB combined with different UV–A levels when the photometer operator is in the back seat or the driver’s seat.
  9. Equation. Lambertian reflection.
  10. Equation. Specular reflection.
  11. Equation. Object fluorescence.
  12. Equation. Contrast ratio.
  13. Equation. Basic ΔLth model.
  14. Equation. Time factor for the ΔLth model.
  15. Equation. Age factor for the ΔLth model.
  16. Equation. Complete ΔLth model.
  17. Equation. Visibility level.
  18. Bar graph. Object illuminance by UV–A level.
  19. Bar graph. Illuminance from each VES by measurement height for the pedestrian object types.
  20. Bar graph. Illuminance from each VES by object position for the pedestrian object types.
  21. Bar graph. Illuminance and distance relationship by lamp and measurement location with the inverse square law trends for the pedestrian object types.
  22. Bar graph. Illuminance on the child’s bicycle and the tire tread for each VES type.
  23. Bar graph. Object luminance by VES for white- and black-clothed pedestrians.
  24. Bar graph. Object luminance by VES for black-clothed pedestrians and cyclist by object position.
  25. Bar graph. Object luminance by VES for black-clothed perpendicular pedestrians by measurement height.
  26. Bar graph. Object luminance by VES for white-clothed pedestrians by object position.
  27. Bar graph. Object luminance by VES for white-clothed perpendicular pedestrian by measurement height.
  28. Bar graph. Object luminance by VES for white-clothed pedestrians by measurement distance.
  29. Bar graph. Object luminance by VES for the child’s bicycle.
  30. Bar graph. Object luminance by VES for the tire tread.
  31. Bar graph. Object luminance by VES for the cyclists’ bicycles.
  32. Bar graph. Background luminance for white- and black-clothed pedestrians by UV–A-based VES.
  33. Bar graph. Influence of VES on background luminance by pedestrian position.
  34. Bar graph. Influence of VES on background luminance by measurement height.
  35. Bar graph. Influence of VES on background luminance by pedestrian type and measurement height.
  36. Bar graph. Influence of VES on background luminance by measurement distance.
  37. Bar graph. Influence of station on background luminance for pedestrians by VES.
  38. Bar graph. Influence of measurement height on background luminance of child’s bicycle by VES.
  39. Bar graph. Influence of station on background luminance for the child’s bicycle by VES.
  40. Bar graph. Influence of measurement height on background luminance for the tire tread by VES.
  41. Bar graph. Influence of station on background luminance for the tire tread by VES.
  42. Bar graph. Reflectance of all objects both dry and wet.
  43. Bar graph. Specular reflection of all bicycle objects for both black-clothed and white-clothed cyclist.
  44. Bar graph. Fluorescence for the black-clothed and white-clothed pedestrians by roadway position.
  45. Bar graph. Fluorescence for the black-clothed and white-clothed objects by VES type.
  46. Bar graph. Fluorescence for the white-clothed objects by VES type and position on the roadway.
  47. Bar graph. Fluorescence of the child’s bicycle by VES type.
  48. Bar graph. Luminance difference by VES for black-clothed pedestrians by object position.
  49. Bar graph. Luminance difference by VES for black-clothed pedestrians by measurement height.
  50. Bar graph. Luminance difference by VES for black-clothed pedestrians by measurement distance.
  51. Bar graph. Luminance difference by VES for white-clothed pedestrians by object position.
  52. Bar graph. Luminance difference by VES for white-clothed pedestrians by measurement distance.
  53. Bar graph. Luminance difference by VES for the child’s bicycle.
  54. Bar graph. Luminance difference by VES for the tire tread.
  55. Bar graph. Visibility level by age and VES for the pedestrian objects.
  56. Bar graph. Visibility level by VES for the black-clothed pedestrian objects by position.
  57. Bar graph. Visibility level by VES for the black-clothed pedestrian objects by distance.
  58. Bar graph. Visibility level by VES for the white-clothed pedestrian objects by position.
  59. Bar graph. Visibility level for the white-clothed pedestrians by distance and VES.
  60. Bar graph. Visibility level for the child’s bicycle by age and VES.
  61. Bar graph. Visibility level for the tire tread by age and VES.
  62. Equation. Weber ratio contrast equation.
  63. Bar graph. Threshold Weber ratio for black-clothed pedestrian objects.
  64. Bar graph. Threshold Weber ratio for white-clothed pedestrian objects.
  65. Bar graph. Threshold visibility level for black-clothed pedestrian objects.
  66. Bar graph. Threshold visibility level for white-clothed pedestrian objects.
  67. Bar graph. Threshold dosage factor for black-clothed pedestrian objects.
  68. Bar graph. Threshold dosage factor for white-clothed pedestrian objects.
  69. Equation. Transmittance of illuminance based on the ratio of the clear measurements.
  70. Equation. Transmittance of luminance based on the ratio of the clear measurements.
  71. Bar graph. Transmittance of the atmosphere for the illuminance, object luminance, and background luminance in the rain.
  72. Line graph. Illuminance for both clear and snow conditions.
  73. Line graph. Transmittance of the atmosphere for the illuminance through snow.
  74. Diagram. Possible reaction of light after collision with a water particle in a fog bank.
  75. Equation. Intensity of light based on the scattering coefficient and incident illuminance.
  76. Diagram. Depiction of the incident beam broken into small lamina.
  77. Equation. Differential change in illuminance for each portion of a light beam.
  78. Equation. Total attenuation according to Bouguer’s law.
  79. Equation. Reduction caused by the fog attenuation.
  80. Scatter plot. Measured backscatter versus the β(θ) function.
  81. Scatter plot. Measured backscatter versus the extinction factor.
  82. Equation. β(θ) function based on the adjusted backscatter.
  83. Equation. Extinction factor based on the adjusted backscatter.
  84. Scatter plot. Backscatter versus β by model.
  85. Scatter plot. Backscatter versus extinction with model.
  86. Bar graph. Threshold Weber ratio for white-clothed pedestrian objects in rain condition.
  87. Bar graph. Threshold visibility level for white-clothed pedestrian objects in rain condition.
  88. Bar graph. Threshold dosage for white-clothed pedestrian objects in rain condition.


LIST OF TABLES

  1. Experimental design.
  2. List of object types.
  3. List of VES configurations.
  4. Station and object relationship.
  5. Components in the measurement process.
  6. Object dimension summarization.
  7. Object reflectance summary.
  8. Pearson correlation coefficients between detection and recognition distances and measured and calculated values for all age, VES, and object types.
  9. Pearson correlation coefficients between detection distance and measured and calculated values for all VES and object types by age.
  10. Pearson correlation coefficients between detection distance and measured and calculated values for all ages and VESs by object types.
  11. Pearson correlation coefficients between detection distance and measured and calculated values for all age and object types by VES.
  12. Critical distance calculation for the objects based on a 6 minute of arc Ricco area.
  13. Fog modeling calibration measurement.
  14. Backscatter measurements in the clear condition.
  15. Correlation results between participant detection distance and photometric metrics for all weather conditions.
  16. Correlation results between participant recognition distance and photometric metrics for all weather conditions.

LIST OF ACRONYMS AND ABBREVIATIONS

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