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Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
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Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
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Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
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Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
×
Page 5
Page 6
Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
×
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Suggested Citation:"Contents." National Academies of Sciences, Engineering, and Medicine. 2020. Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview. Washington, DC: The National Academies Press. doi: 10.17226/25679.
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i CONTENTS CHAPTER 1. INTRODUCTION ............................................................................................................. 1 REPORT OVERVIEW AND ORGANIZATION .................................................................................................................. 1 RESEARCH OBJECTIVES ............................................................................................................................................. 1 KEY FINDINGS ........................................................................................................................................................... 2 RESEARCH APPROACH ............................................................................................................................................... 3 CHAPTER 2. CURRENT STATE OF SSL ADOPTION AND GUIDANCE ...................................... 5 INTRODUCTION .......................................................................................................................................................... 5 SURVEY METHODS .................................................................................................................................................... 5 SURVEY RESULTS ...................................................................................................................................................... 5 State of Adoption, Construction, and Maintenance of LED Roadway Lighting ................................................... 5 Design Guidelines and Criteria for LED Roadway Lighting ................................................................................ 6 CONCLUSION ............................................................................................................................................................. 6 CHAPTER 3. STRUCTURE OF SSL GUIDE ......................................................................................... 7 AASHTO ROADWAY LIGHTING DESIGN GUIDE ....................................................................................................... 7 SOLID STATE LIGHTING GUIDE.................................................................................................................................. 8 CHAPTER 4. LITERATURE REVIEW AND GAP ANALYSIS ....................................................... 11 DIFFERENCES BETWEEN SSL AND HID FIXTURES ................................................................................................... 11 OFF-ROADWAY LIGHTING ....................................................................................................................................... 16 METRICS FOR LIGHTING .......................................................................................................................................... 18 DIRT DEPRECIATION / LIGHT LOSS FACTOR ............................................................................................................ 20 DISABILITY AND DISCOMFORT GLARE .................................................................................................................... 22 CONSIDERATIONS FOR PEDESTRIANS, CYCLISTS, AND MOTORISTS ......................................................................... 23 COST BENEFIT METHODOLOGIES ............................................................................................................................ 27 APPLICATIONS AND OBSTACLES TO ADAPTIVE LIGHTING ....................................................................................... 29 IMPACTS OF WEATHER AND CLIMATE ON LIGHTING EFFECTIVENESS ..................................................................... 31 APPLICATION TO FREEWAYS, ARTERIALS, INTERSECTIONS, AND INTERCHANGES ................................................... 33 HIGH-MAST LIGHTING ............................................................................................................................................ 35 POTENTIAL ENVIRONMENTAL AND HEALTH EFFECTS ............................................................................................. 36 AGING DRIVERS ...................................................................................................................................................... 39 SUMMARY ............................................................................................................................................................... 41 CHAPTER 5. RESEARCH AND TESTING RESULTS ..................................................................... 43 SMART ROAD TESTING ............................................................................................................................................ 43 Experimental Methods ........................................................................................................................................ 43 Equipment and Facilities .................................................................................................................................... 48 Experimental Procedure ..................................................................................................................................... 56 Analyses .............................................................................................................................................................. 56 Results ................................................................................................................................................................. 59 Discussion ........................................................................................................................................................... 83 Conclusion .......................................................................................................................................................... 86 RESEARCH ROADMAP .............................................................................................................................................. 86 Metrics for Assessing the Effectiveness of Roadway Lighting, With and Without Headlights to Achieve Adequate Contrast .............................................................................................................................................. 86 Standardization and Asset Management for SSL Replacement to Simplify Maintenance ................................... 87 Potential Revenue Streams from Data Collection and Barriers to their Implementation................................... 87 Real-time Asset Management within the Context of ITS Framework ................................................................. 87

ii Metrics to Characterize the Environment and Health Effects of Roadway Light Spectrum, Amount, Distribution, and Timing..................................................................................................................................... 88 Metrics for Assessing Light Depreciation and Means of Determining End of Useful Life ................................. 88 REFERENCES .......................................................................................................................................... 89 APPENDIX A: SURVEY RESULTS .................................................................................................... A-1 APPENDIX B: DOT MANUALS AND SPECIFICATIONS .............................................................. B-1 APPENDIX C: ILLUMINANCE CHARACTERIZATION TABLES .............................................. C-1

iii LIST OF TABLES Table 1. Excerpt from IES RP-8-14 Showing Street Lighting Levels by Pedestrian Volume .............. 29 Table 2. Detection Distances of Luminaires from Evaluations Comparing Different Lighting Systems .................................................................................................................................... 34 Table 3. Independent Variables and their Levels Used in the Study ..................................................... 44 Table 4. Discomfort Glare Rating Scale Used in this Study ................................................................. 47 Table 5. Average Vertical and Horizontal Illuminance Levels Across Different Light Types, Shield Conditions and Light Levels ........................................................................................ 52 Table 6. Uniformity Ratios of Illuminance Across Different Light Types, Shield Conditions and Light Levels ............................................................................................................................. 53 Table 7. Surround Ratios of Illuminance Across Different Light Types, Shield Conditions and Light Levels ............................................................................................................................. 54 Table 8. Vertical Illuminances Measured at the Pedestrian and Target Locations in the HUR- HSR Shield Condition ............................................................................................................. 55 Table 9. Vertical Illuminances Measured at the Pedestrian and Target Locations in the Surround and Uniformity Shield Conditions .......................................................................................... 55 Table 10. Significant Statistical Results from the LMM Analysis of Detection Distance of LED Light Source Comparison ........................................................................................................ 60 Table 11. Significant Statistical Results from the MMLR Analysis of Type of Stop of Pedestrians Under LED Light Source Comparison .................................................................................... 70 Table 12. Odds Ratios of Significant Factors in MMLR Analysis of Detection of Pedestrians ............. 70 Table 13. Significant Statistical Results from the LMM Analysis of Detection Distance of Targets Under LED Light Source Comparison ....................................................................... 71 Table 14. Significant Statistical Results from the MMLR Analysis of Type of Stop of Targets Under LED Light Source Comparison .................................................................................... 78 Table 15. Odds Ratios of Significant Factors in MMLR Analysis of Detection of Pedestrians ............. 79 Table 16. Significant Statistical Results from the LMM Analysis of Detection Distance of Pedestrians Under LED and HPS Light Source Comparison .................................................. 79 Table 17. Significant Statistical Results from the MMLR Analysis of Type of Stop of Pedestrians Under LED and HPS Light Source Comparison ..................................................................... 80 Table 18. Odds Ratios of Significant Factors in MMLR Analysis of Detection of Pedestrians ............. 81 Table 19. Significant Statistical Results from the LMM Analysis of Detection Distance of Targets Under LED and HPS Light Source Comparison ........................................................ 81 Table 20. Significant Statistical Results from the LMM Analysis of Discomfort Glare Perception Under LED Light Sources ....................................................................................................... 82 Table 21. 2100K HPS Horizontal Illuminance .......................................................................................... 1 Table 22. 2100 HPS Vertical Illuminance ................................................................................................. 1 Table 23. 5000K LED HUR-HSR Horizontal Illuminance ....................................................................... 1 Table 24. 5000K LED HUR-HSR Vertical Illuminance ........................................................................... 2 Table 25. 4000K LED HUR-HSR Horizontal Illuminance ....................................................................... 2 Table 26. 4000K LED HUR-HSR Vertical Illuminance ........................................................................... 3 Table 27. 3000K LED HUR-HSR Horizontal Illuminance ....................................................................... 3 Table 28. 3000K LED HUR-HSR Vertical Illuminance ........................................................................... 4

iv Table 29. 4000K LED HUR-LSR Horizontal Illuminance ....................................................................... 4 Table 30. 4000K LED HUR-LSR Vertical Illuminance ........................................................................... 5 Table 31. 4000K LED LUR-HSR Horizontal Illuminance ....................................................................... 5 Table 32. 4000K LED LUR-HSR Vertical Illuminance ........................................................................... 6 Table 33. 4000K LED LUR-LSR Horizontal Illuminance ........................................................................ 6 Table 34. 4000K LED LUR-LSR Vertical Illuminance ............................................................................ 7 LIST OF FIGURES Figure 1. Overview of the NCHRP Project 05-22 Workflow ................................................................... 3 Figure 2. Spectral Power Distribution of Overhead-Lighting Types ...................................................... 12 Figure 3. Mean Detection Distance Differences for Various Light Sources .......................................... 13 Figure 4. TM-21 Inputs for Predicting Luminance Maintenance ........................................................... 14 Figure 5. Example of Driver Life Determined by MTBF Analysis ........................................................ 15 Figure 6. Comparisons of HPS and LED Luminaires using Standardized Distribution Ratings ............ 15 Figure 7. Excerpt from CIE 115 – Table 2 ............................................................................................. 17 Figure 8. Effect of Lumen and Dirt Depreciation with Cleaning ........................................................... 21 Figure 9. Lumen and Dirt Depreciation for Different Optical Assemblies ............................................ 21 Figure 10. Night-to-Day Crash Rate Ratio to Lighting Level .................................................................. 25 Figure 11. Night-to-Day Crash Rate Ratio to Lighting Level for Various Road Classes ......................... 25 Figure 12. Overhead-Lighting Level Experiment – SNK Groupings for Pedestrian Detection Distance with Headlamps on by Overhead-Lighting Level .................................................... 26 Figure 13. Excerpt from FHWA Adaptive Lighting Report – Classification Method for Streets ............ 30 Figure 14. Detection Distance by Weather Conditions and Light Source ................................................ 32 Figure 15. High-Mast Lighting and Light Trespass Example .................................................................. 35 Figure 16. Yellowing of the Human Lens with Age ................................................................................. 40 Figure 17. Spectral Power Distributions of the Light Sources Used to Measure Drivers’ Visual Performance and Discomfort Glare Perception ....................................................................... 45 Figure 18. Locations of the Offset Locations with Respect to the Vehicle Travel Direction on the Virginia Smart Road ................................................................................................................ 47 Figure 19. Smart Road Lighting System .................................................................................................. 48 Figure 20. (a) No Shield on the Luminaire Representing High Uniformity-High Surround, (b) Luminaire with High Uniformity-Low Surround Shield, (c) Luminaire with Low Uniformity-High Surround Shield, (d) Luminaire with Low Uniformity-Low Surround Shield ....................................................................................................................................... 49 Figure 21. Red, Gray, and Blue Targets ................................................................................................... 49 Figure 22. Spectral Reflectances of the Three Colored Targets Used in the Study .................................. 50 Figure 23. Pedestrians in Colored Scrubs ................................................................................................. 50 Figure 24. Spectral Reflectance of the Colored Scrubs Used in the Study ............................................... 51 Figure 25. Location of the Calibrated Photometer Inside the Test Vehicle at the Driver’s Seat .............. 58 Figure 26. Sample Image Output from the Photometer and the Method Used to Measure the Luminance of the Pedestrian by Tracing Polygons ................................................................. 59

v Figure 27. Interactive Effect of Light Source Type, Surround Ratio, and Offset on Detection Distance ................................................................................................................................... 61 Figure 28. Change in Luminance as the Vehicle Approaches the Pedestrian Locations .......................... 62 Figure 29. Change in Contrast as the Vehicle Approaches the Pedestrian Locations .............................. 63 Figure 30. Average Contrasts of the Pedestrians at the Instance of Detection for Each Pedestrian Location Under Both Surround Ratio Conditions ................................................................... 64 Figure 31. Interactive Effect of Light Source Type, Surround Ratio, and Speed on Detection Distance ................................................................................................................................... 64 Figure 32. Interactive Effect of Light Level, Surround Ratio, and Clothing Color on detection Distance ................................................................................................................................... 65 Figure 33. Interactive Effect of Light Level, Surround Ratio, and Offset on Detection Distance ............ 66 Figure 34. Change in Pedestrian Luminance at Different Light Levels as Vehicles Approached the Pedestrian ................................................................................................................................ 67 Figure 35. Change in Pedestrian Contrast at Different Light Levels as Vehicles Approached the Pedestrian ................................................................................................................................ 67 Figure 36. Average Contrasts of the Pedestrians at Detection for Each Pedestrian Location Under Both the Surround Ratio Conditions at the Three Light Levels .............................................. 68 Figure 37. Interactive Effect of Uniformity Ratio, Surround Ratio, and Speed on Detection Distance ................................................................................................................................... 69 Figure 38. Interactive Effect of Age and Surround Ratio on Detection Distance..................................... 69 Figure 39. Interactive Effect of Light Source Type, Light Level, and Uniformity Ratio on Detection Distance .................................................................................................................. 72 Figure 40. Interactive Effect of Light Type, Light Level, and Surround Ratio on Detection Distance of Targets .................................................................................................................. 73 Figure 41. Change in Target Luminance as the Vehicle Approaches the Target Under Different Light Levels ............................................................................................................................. 74 Figure 42. Change in Target Contrast as the Vehicle Approaches the Target Under Different Light Levels ...................................................................................................................................... 74 Figure 43. Average Target Contrasts at Detection at Each Light Level Under Different Light Levels ...................................................................................................................................... 75 Figure 44. Interactive Effects of Light Source Type and Target Color at the High Uniformity Ratio ........................................................................................................................................ 76 Figure 45. Change in Target Luminance and Contrast Across the Three Colored Targets as the Vehicle Approached the Target ............................................................................................... 76 Figure 46. Average Contrasts of the Blue-, Gray-, and Red-Colored Targets at Detection ..................... 77 Figure 47. Interactive Effect of Light Level, Speed and Offset on Detection Distance of Targets .......... 77 Figure 48. Interactive Effect of Age and Light Level on Detection Distance of Targets ......................... 78 Figure 49. Effect of Light Source Type on the Detection Distance of Pedestrians .................................. 80 Figure 50. Effect of Light Source Type on the Detection Distance of Targets ........................................ 82 Figure 51. Effect of Light Level on Discomfort Glare Rating ................................................................. 83

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Providing light beyond the limits of the roadway travel lanes benefits drivers’ visual performance, spectral content of light-emitting diode (LED) sources should be a design consideration, and there are not currently any health impacts from properly designed roadway lighting are among the findings of this survey report.

The TRB National Cooperative Highway Research Program's pre-publication draft of NCHRP Research Report 940: Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview determines the current guidance for the use of Solid State Lighting (SSL); identifies the research that still needs to be accomplished to assist in its proper implementation; and develops a comprehensive, easy to use, set of guidelines using currently available information and new research being proposed as part of this project.

Also see this guide's accompanying pre-publication draft, NCHRP Research Report 940: Solid-State Roadway Lighting Design Guide: Volume 1: Guidance.

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