Solid-State Roadway Lighting Design Guide: Volume 1: Guidance (2020)

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ANNEX A Design Examples 71 Freeway Design Example Using AASHTO GL-7 and SSL Guideline 78 Street Design Example Using AASHTO GL-7 and SSL Guideline 70 

Design Examples   71   Freeway Design Example Using AASHTO GL-7 and SSL Guideline Step 1. Develop a Master Lighting Plan Example Result: Create a formal arrangement between the local governments and other entities within the regional area to coordinate and standardize the design, operation, and maintenance of the public lighting. Include curfews and monitoring and control systems. o Coordination with agency and set goals 45-ft mounting height restriction with 8-ft arm max. length o Curfews o Electric and lighting management systems o Conduct applicable studies o SSL considerations: Determine adaptive lighting technology Determine Smart city needs Selection of luminaires to meet goals Standardize O&M limitations Environmental sensitivity Step 2. Lighting Design Step 2a – Determine illuminance or luminance design. Example Result: Both illuminance and luminance will be used for freeway calculations. Step 2b – Determine the road surface classification to properly design a roadway lighting system. Example Result: Asphalt, Class R3. 

72   Solid-State Roadway Lighting Design Step 2c – Determine warranting conditions. Example Result: Warranting condition, sections in and near cities where the current average daily traffic (ADT) is 30,000 or greater, CFL-1. Warranting conditions can also be applied from the SSL Guidance for crash modification factors. Lighting was decided to be added. Step 2d – Pole placement. Example Result: Existing lighting locations in center median, new lighting system will utilize existing duct bank. Therefore, light pole locations will be in the center median. 

Design Examples   73   Step 2e – Determine design levels. Example Result: Using Table 3-5a for Interstate and other freeways. Step 2f – SSL consideration. Example Result: Project master plan requires SSL. 

74   Solid-State Roadway Lighting Design Step 2g – Determine levels for adaptive lighting. Example Result: Class H3, using FHWA-HRT-14-050, Guidelines for the Implementation of Reduced Lighting on Roadways, which would not allow for this system to be dimmed. Step 2h – Source color selection. Example Result: Based on the research provided in the SSL Guidance, a 4000K CCT LED source will be used. Step 2i – Consider the surround ratio as part of design. Example Result: The surround ratio will be included: SR = 0.8 Figure 19 - Example Diagram for Applying Surround Ratio 

Design Examples   75   Step 3. Maintenance Considerations in Roadway Lighting Design Step 3a – Select appropriate maintenance factors for luminaire dirt depreciation (LDD), lamp lumen depreciation (LLD), and luminaire ambient temperature factor (LATF) to apply a total light loss factor (LLF) to the lighting design. Example Result: SSL specific maintenance factors are LDD = 0.9, LLD = 0.82, and LATF = 1; then LLF = 0.738. Step 4. Sky Glow, Trespass, Environmental Impacts Step 4a – Determine lighting zone. Example Result: LZ2 Step 4b – Determine mitigation of sky glow and trespass Example Result: Maximum illuminance 0.3 fc. 

76   Solid-State Roadway Lighting Design FREEWAY PARAMETERS FREEWAY DESIGN 

Design Examples   77   FREEWAY LIGHTING CALCULATION 

78   Solid-State Roadway Lighting Design Street Design Example Using AASHTO GL-7 and SSL Guideline Step 1. Develop a Master Lighting Plan Example Result: Create a formal arrangement between the local governments and other entities within the regional area to coordinate and standardize the design, operation, and maintenance of the public lighting. Include curfews and monitoring and control systems. o Coordination with agency and set goals 35-ft mounting height restriction with 6-ft arm max. length o Curfews o Electric and lighting management systems o Conduct applicable studies o SSL considerations: Determine adaptive lighting technology Determine Smart city needs Selection of luminaires to meet goals Standardize O&M limitations Environmental Sensitivity Step 2. Lighting Design Step 2a – Determine illuminance or luminance design. Example Result: Both illuminance and luminance will be used for freeway calculations. Step 2b – Determine the road surface classification to properly design a roadway lighting system. Example Result: Asphalt, Class R3 

Design Examples   79   Step 2c – Determine warranting conditions. Example Result: Warranting conditions applied from the SSL Guidance for crash modification factors (CMF) suggest that if the street is previously unlit, then a CMF of 0.72 can be used. Step 2d – Pole placement. Example Result: The new lighting system will be illuminated from the westbound shoulder. 

80   Solid-State Roadway Lighting Design Step 2e – Determine design levels. Example Result: Using Table 3-5a for Interstate and other freeways. Step 2f – SSL consideration. Example Results: Project master plan requires SSL. 

Design Examples   81   Step 2g – Determine levels for adaptive lighting. Example Results: Using IES RP-8-18, Chapter 11, “Lighting Design Criterial for Streets,” the lighting can be dimmed when the pedestrian activity falls from a medium to a low classification. Lavg: Maintained average pavement luminance L min: Minimum pavement luminance Lmax: Maximum pavement luminance LV,max: Maximum veiling luminance Step 2h – Source color selection. Example Results: Based on the research provided in the SSL Guidance a 4000K CCT LED source will be used. Step 2i – Design to sidewalk illumination levels and consider surround ratio as part of design. Example Results: Sidewalk levels and surround ratio will be evaluated. Figure 19 - Example Diagram for Applying Surround Ratio 

82   Solid-State Roadway Lighting Design Step 3. Maintenance Considerations in Roadway Lighting Design Step 3a – Select appropriate maintenance factors for luminaire dirt depreciation (LDD), lamp lumen depreciation (LLD), and luminaire ambient temperature factor (LATF) to apply a total light loss factor (LLF) to the lighting design. Example Results: SSL specific maintenance factors are LDD = 0.9, LLD = 0.9, LATF = 1; then LLF = 0.81 Step 4. Sky Glow, Trespass, Environments Impacts Step 4a – Determine lighting zone. Example Result: LZ3 Step 4b – Determine mitigation of sky glow and trespass. Example Result: Maximum illuminance 0.8 fc. 

Design Examples   83   STREET PARAMETERS STREET DESIGN 

84   Solid-State Roadway Lighting Design STREET LIGHTING CALCULATION