Solid-State Roadway Lighting Design Guide: Volume 2: Research Overview (2020) / Chapter Skim
Currently Skimming:
Pages 9-37
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 9... ...
9 This chapter reviews the relevant research applicable to SSL and its application to roadway lighting and provides a gap analysis detailing available information, missing information, and strategies for addressing those gaps in this and future research. Differences Between Solid-State Lighting and High-Intensity Discharge Fixtures Until recently, the majority of roadway lighting was HID, specifically, HPS.
|
From page 10... ...
10 Solid-State Roadway Lighting Design LEDs can be customized for their intended use. They can be acutely dimmed to specific levels (Dyble et al.
|
From page 11... ...
Literature Review and Gap Analysis 11 inherently involves low-light vision, luminance contrast typically prevails; however, color contrast can vastly improve an object's visibility (Lutkevich et al.
|
From page 12... ...
Source: IES (2011)
|
From page 13... ...
Literature Review and Gap Analysis 13 Note: Tcase = temperature of the case of the driver. Figure 5.
|
From page 14... ...
14 Solid-State Roadway Lighting Design Differences Between ssL anD HiD fixtures (continued) • Commonly used LED sources may result in varied glare responses.
|
From page 15... ...
Literature Review and Gap Analysis 15 In general, VL values are only comparable to other VLs calculated in the same scenario. No scales display VL benchmarks for visibility; therefore, VL has generalizable limitations.
|
From page 16... ...
16 Solid-State Roadway Lighting Design a source, respectively, and are the most prominent and often the easiest characteristics for measuring aspects of light. Depending on the amount of light in a given scenario, different modes of human vision come into play: photopic, scotopic, and mesopic.
|
From page 17... ...
Literature Review and Gap Analysis 17 The X-model and the MOVE model have different photometric limits at which the mesopic range becomes active because the upper luminance limit of the X-model is 0.6 cd/m2, whereas the upper luminance limit of the MOVE model is 10 cd/m2. The X-model was based on achromatic tasks, while the MOVE model was based on chromatic tasks.
|
From page 18... ...
18 Solid-State Roadway Lighting Design Dirt Depreciation/Light Loss Factor The construction of SSL luminaires is different from that of HID luminaires. Some optical systems use individual LEDs with individual refractors, others use external lenses, and still others use reflector systems or light guides as part of their design.
|
From page 19... ...
Literature Review and Gap Analysis 19 luminaires also have an automatic output adjustment if the temperature of internal fixture gets too high. Failure of an LED luminaire often occurs at the LED driver, the estimated failure rate of which is determined by MTBF calculations.
|
From page 20... ...
20 Solid-State Roadway Lighting Design Discomfort glare is a further result of overly bright light sources in the field of view and causes a sense of pain or annoyance. While its exact cause is not known, it may result from pain in the muscles that cause the pupil to close.
|
From page 21... ...
Literature Review and Gap Analysis 21 Considerations for Pedestrians, Cyclists, and Motorists The volume of road users at night is far less than during the day; even so, areas where traffic volumes and the rate of conflict between drivers and pedestrians are higher are typically lighted with artificial lighting to improve safety. In addition, locations where pedestrians and cyclists are common are typically lighted to specifications regarding their visibility and safety (IES 2018)
|
From page 22... ...
22 Solid-State Roadway Lighting Design Source: Gibbons et al.
|
From page 23... ...
Literature Review and Gap Analysis 23 roadway lighting doubles the distance at which a pedestrian is visible (Gibbons et al.
|
From page 24... ...
24 Solid-State Roadway Lighting Design cOnsiDeratiOns fOr peDestrians, cycLists, anD MOtOrists What We Know • Research has shown the impact of lighting on safety. • Nighttime risks are greatest for pedestrians and cyclists.
|
From page 25... ...
Literature Review and Gap Analysis 25 Several other factors can be considered in a cost–benefit analysis, depending on power costs and utility agreements, such as the use of adaptive lighting technologies and asset management tools and the availability of energy rebates, if applicable. The contracting methodology, which would include things like asset value, lease opportunities, and the cost of money, also can be considered in the analysis.
|
From page 26... ...
26 Solid-State Roadway Lighting Design lighting controls. Energy savings between 84% and 87% were observed.
|
From page 27... ...
Literature Review and Gap Analysis 27 Source: Gibbons et al.
|
From page 28... ...
28 Solid-State Roadway Lighting Design appLicatiOns anD OBstacLes tO aDaptive LigHting (continued) Results/Recommendations of This Study • Guidance is included in the SSL Guide.
|
From page 29... ...
Literature Review and Gap Analysis 29 With the advent of adaptive lighting technologies, it may soon be possible for lighting to change in response to weather conditions. In cases of severe inclement weather, such as heavy rain or fog, it may be best for lighting to be dimmed or for the spacing to be increased (Boyce 2009)
|
From page 30... ...
30 Solid-State Roadway Lighting Design Application to Freeways, Arterials, Intersections, and Interchanges SSL lighting is applicable to all forms of outdoor lighting, including freeways, arterials, intersections, and most modern architecture. LEDs have already replaced many incandescent systems in the transportation industry, including signalized lights and some headlamps.
|
From page 31... ...
Literature Review and Gap Analysis 31 so the locations themselves are not directly comparable. It is also important to note that the light sources used in those comparisons differed by manufacturer and experimental location; however, at the same testing sites, the LEDs were the best performers in terms of visibility.
|
From page 32... ...
32 Solid-State Roadway Lighting Design example of typical light trespass issues often seen with high-mast lighting. Shielding LED luminaires is sometimes more difficult because, instead of a single lamp with a reflector, luminaires include several point sources of light, and conventional side shielding is not as effective.
|
From page 33... ...
Literature Review and Gap Analysis 33 and Bierman 2014)
|
From page 34... ...
34 Solid-State Roadway Lighting Design of this research found that objects lighted with a 4100K CCT had as much as a 20% higher detection distance over other color temperatures. Detection distances of color targets were also the highest for the 4100K CCT LED.
|
From page 35... ...
Literature Review and Gap Analysis 35 in areas of darkness. Because the health, growth, behavior, and maturity of some plants and wildlife can be affected by roadway lighting, it is important to engage in research that leads to favorable outcomes for both ecology and highway safety.
|
From page 36... ...
36 Solid-State Roadway Lighting Design Yellowing of the lens is not the most dire or prevalent physiological issue facing older drivers. Medical conditions such as diabetic retinopathy (National Eye Institute 2015b)
|
From page 37... ...
Literature Review and Gap Analysis 37 aging Drivers What We Know • Age-related changes in the eye have the potential to cause issues for the older driver. • The spectral responsivity of the eye with age (yellowing)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.