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Troy, N.Y. -  6/10/2014

Lighting Research Center Authors National Academies Report on New Roadway Lighting Technologies

LEDs Ready for Prime Time, Not All Systems Perform Equally Well

roadway lightingThe rapid development of lighting technologies, particularly solid-state systems using light emitting diodes (LEDs), has opened a universe of new possibilities as well as new questions about roadway lighting in the U.S., which for decades has been dominated by the use of high pressure sodium (HPS) lamps. Other light source technologies have also been angling for roadway market share. There is a critical need for objective technical information about new types of roadway lighting among transportation agencies. In response, the Transportation Research Board (TRB), part of the National Academies, initiated a project to evaluate new lighting technologies and identify new metrics for comparison. Lighting Research Center (LRC) scientists John Bullough, who served as principal investigator, and Leora Radetsky co-authored the report, entitled "Analysis of New Highway Lighting Technologies." The LRC is part of Rensselaer Polytechnic Institute, the nation’s oldest technological research university.
 
A major challenge in assessing new roadway lighting technologies is that information for different systems is given in different forms, making comparisons difficult. Bullough and Radetsky systematically analyzed the performance of a number of representative luminaires of each type, and developed a consistent "data sheet" format, allowing direct comparisons. They found that many commercially available LED, ceramic metal halide, and plasma discharge roadway lighting systems can meet existing standards for lighting collector roads and freeways, achieving comparable or greater pole spacing than HPS systems and in many cases, resulting in lower energy use.  
 
Importantly, say Bullough and Radetsky, not all systems of each type performed equally well. This underscores the importance of developing consistent data reporting formats such as those in their report.
 
The authors found that pole height was an important factor in the overall effectiveness of the roadway lighting system. A metric developed by the LRC, called luminaire system application efficacy (LSAE), can be used to optimize pole height and spacing to achieve optimal economic performance of different roadway lighting designs. Bullough and Radetsky also recommend that transportation agencies begin considering new benefit metrics for roadway lighting including photometric quantities based on mesopic vision, brightness perception and visual comfort.
 
According to Bullough, "Technologies such as LEDs are becoming mainstream choices for roadway lighting. The findings in our report can help agencies make better decisions as they face these choices."
 
The report by Bullough and Radetsky can be downloaded from the TRB website at: http://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP20-07(305)_FR.pdf.

About the Lighting Research Center
The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute is the world's leading center for lighting research and education. Established in 1988 by the New York State Energy Research and Development Authority (NYSERDA), the LRC has been pioneering research in solid-state lighting, light and health, transportation lighting and safety, and energy efficiency for nearly 30 years. LRC lighting scientists with multidisciplinary expertise in research, technology, design, and human factors, collaborate with a global network of leading manufacturers and government agencies, developing innovative lighting solutions for projects that range from the Boeing 787 Dreamliner to U.S. Navy submarines to hospital neonatal intensive-care units. LRC researchers conduct independent, third-party testing of lighting products in the LRC's state of the art photometric laboratories, the only university lighting laboratories accredited by the National Voluntary Laboratory Accreditation Program (NVLAP Lab Code: 200480-0). In 1990, the LRC became the first university research center to offer graduate degrees in lighting and today, offers a M.S. in lighting and a Ph.D. to educate future leaders in lighting. With 35 full-time faculty and staff, 15 graduate students, and a 30,000 sq. ft. laboratory space, the LRC is the largest university-based lighting research and education organization in the world.

About Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute, founded in 1824, is America’s first technological research university. The university offers bachelor’s, master’s, and doctoral degrees in engineering; the sciences; information technology and web sciences; architecture; management; and the arts, humanities, and social sciences. Rensselaer faculty advance research in a wide range of fields, with an emphasis on biotechnology, nanotechnology, computational science and engineering, data science, and the media arts and technology. The Institute has an established record of success in the transfer of technology from the laboratory to the marketplace, fulfilling its founding mission of applying science “to the common purposes of life.”