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Troy, N.Y. -  11/26/2012

Ecoluminance: LRC Develops New Method to Light Roundabouts

Roundabouts, also known as traffic circles, are increasing in number across the U.S. These intersections generally increase traffic throughput while reducing the severity of automobile accidents. However, as relatively new traffic features, modern roundabouts are sometimes described as confusing for drivers. One difference between roundabouts and conventional cross-type intersections is the location of pedestrian crosswalks. Drivers may be less familiar with the location of crosswalks when driving through a roundabout.

The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute has developed a concept for roadway illumination called "Ecoluminance" which incorporates roadside vegetation with low-level pedestrian and landscape lighting, retroreflective markers, and light-emitting diode (LED) road and walkway illumination.

In a study sponsored jointly by the New York State Energy Research and Development Authority (NYSERDA) and by the New York State Department of Transportation (NYSDOT), the LRC designed, installed and evaluated new lighting approaches in real-world conditions. Senior Research Scientist John Bullough and LRC Director Mark Rea were the principal investigators for the study.

“Ecoluminance uses a combination of lighting and vegetation to provide visual delineation, illumination for important safety hazards and concerns, and cues about road geometry,” said Bullough.

The ecoluminance concept was implemented at a roundabout in the Town of Bethlehem in Albany County, New York with cooperation from the Town Board and the Public Works, Highway, Planning, and Police Departments. Researchers from the State University of New York College of Environmental Science and Forestry also assisted with the study, and companies General Electric Lighting, Forms + Surfaces and Lightspec Albany donated luminaires to the project.

During two preliminary demonstrations during the summer of 2011, the LRC installed lights and vegetation and obtained feedback from NYSERDA and NYSDOT engineers as well as from town officials and the Town of Bethlehem Bicycle and Pedestrian Committee. Based on this feedback, the LRC installed vegetation and retroreflective markers in the central island of the roundabout, LED landscape lighting to illuminate vegetation and trees, bollards at crosswalks, and LED overhead lighting along sidewalks and the road during the summer of 2012. Roadway edges and pedestrians were more visible than under the conventional lighting, and vehicles approached the roundabout with similar or slightly lower speeds.

Traditional lighting for roundabouts consists of a relatively large number of pole-mounted overhead luminaires, which are relatively expensive to operate because they are energy intensive. The LRC estimates that the initial cost of the ecoluminance system is similar to that of conventional lighting, but the energy use is only about a fourth, resulting in substantially lower energy costs as well as substantially lower light pollution impacts. "The ecoluminance concept could allow transportation agencies to integrate vegetation and lighting while reducing costs and environmental impacts," said Rea.

The LRC's report is available online at:

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.”