Roadway lighting sources are being converted from high pressure sodium (HPS) and other high-intensity discharge (HID) luminaires to light emitting diode (LED) luminaires because LEDs are generally more energy efficient and may offer better visibility. LEDs with a correlated color temperature (CCT) greater than 3000K often have higher blue content in their spectrum (460 to 480 nm) than HPS lamps. Light in this wavelength affects the production of the hormone melatonin, which regulates the human circadian rhythm. In June 2016, the American Medical Association (AMA) issued a report (The Council on Science and Public Health Report 2-A-16, Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting) noting that roadway lighting with higher blue content, such as the light produced by LEDs with higher CCTs, could adversely suppress melatonin and affect the sleep health of people exposed to it. However, a link between melatonin suppression and LED lighting at roadway levels has never been reported. There could, however, be an advantage to the blue content in the LEDs. Because the blue content in LEDs has the potential to suppress melatonin, then by extension it may have the potential to make drivers more alert.
In order to design LED roadway lighting that minimizes any negative impacts on drivers, research is needed to understand the relationship between LED roadway lighting and driver sleep health and alertness.
The objective of this research is to develop a guidance document for state DOTs that (1) describes the effects of LED roadway lighting on the sleep health and alertness of drivers, with attention to the illuminance, duration, and spectral power distribution (SPD) of the LED lighting; (2) compares these effects to those of (a) high-intensity discharge (HID) lighting and (b) the absence of roadway lighting; and (3) suggests methods to mitigate the effects, if any, of LED roadway lighting on sleep health and alertness. In this research, the term “sleep health” shall be construed to mean circadian disruption.
Proposers are asked to provide a detailed research plan for accomplishing the project objective and for producing the deliverables required by each phase of the project. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the objective. The work proposed for each phase must be divided into tasks and proposers must describe the work proposed in each task in detail.
Deliverables shall include, at a minimum:
1. A critical review of the literature (with particular attention to that published since 2014) on the potential effects of the SPD, illuminance, and duration of LED lighting at roadway levels on human sleep health and alertness, with attention to the measurement methodology.
2. A proposed Phase II work plan to experimentally determine:
· Typical levels of corneal illuminance and typical durations of exposure from LED roadway lighting as a function of SPD compared to that from common LED devices such as tablets, TVs, phones, and dashboards, as well as from low-beam and high-beam HID and LED vehicle headlamps.
· The threshold of corneal illuminance from LED roadway lighting necessary to produce a measurable effect—objective, subjective, or both—on the sleep health and alertness of a vehicle operator as a function of SPD and duration.
· How these effects compare to those of HID lighting and of the absence of roadway lighting.
3. An interim report that presents the critical literature review and the proposed Phase II work plan.
1. Execution of the work plan approved in Phase I.
2. A guidance document for state DOTs that presents (a) the thresholds (objective, subjective, or both) of LED roadway lighting at which effects are seen on driver sleep health and alertness; (b) comparison of these thresholds with typical exposure from other common LED devices as well as from HID roadway lighting and from the absence of roadway lighting; and (c) suggested methods to mitigate the effects, if any, of LED roadway lighting on sleep health and alertness.
3. A final report that documents results, summarizes findings, draws conclusions, and presents (a) the guidance document for state DOTs and (b) suggestions for needed future research on this topic.
STATUS: Proposals have been received in response to the RFP. The panel will meet to select a contractor to perform the work.