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Troy, N.Y. -  7/20/2018

Evaluating the Impact of Warning Lights on Roadway Worker Safety

Lighting Research Center and Penn State Collaborate on Transportation Lighting Study

Flashing warning lights are a common line of defense intended to help protect construction workers, police officers, firefighters, emergency medical service personnel, and others who work along the roadway from oncoming traffic. These lights need to capture drivers' attention yet not be so bright that they distract drivers from seeing workers in and along the roadway.

In collaboration with Pennsylvania State University, the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute conducted a field study to measure drivers' ability to detect simulated workers adjacent to vehicles equipped with flashing yellow warning beacons varying in peak intensity (25 cd to 700 cd) and flash frequency (1 Hz or 4 Hz), while driving at night. Crash reports reveal that workers do not always wear reflective vests when working along the roadway, thus the study was conducted with and without safety vests on the simulated workers.

The results of the study were recently published in the journal Accident Analysis & Prevention. The paper, “Investigation of flashing and intensity characteristics for vehicle-mounted warning beacons” is authored by Kristin Kersavage, Nicholas Skinner, John Bullough, Philip Garvey, Eric Donnell, and Mark Rea.

The research team found that there was no difference in detection distances between lights flashing at 1 Hz or those flashing at 4 Hz. Detection distances were shortest when the peak intensity of the warning beacons was greater than 150 cd. As expected, the simulated workers wearing safety vests were seen from furthest away where drivers would have the most time to respond, regardless of the warning beacon peak intensity.
The study results can be incorporated into performance standards for flashing warning beacons to ensure that they support worker safety, especially at night.
Funding for this study was provided by the National Institute for Occupational Safety and Health (NIOSH Grant # R01OH010165 to Mark Rea, LRC).

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 conducts research in light and human health, transportation lighting and safety, solid-state lighting, energy efficiency, and plant health. 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. 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. Learn more at

About Rensselaer Polytechnic Institute
Founded in 1824, Rensselaer Polytechnic Institute is America's first technological research university. Rensselaer encompasses five schools, 32 research centers, more than 145 academic programs, and a dynamic community made up of more than 7,900 students and more than 100,000 living alumni. Rensselaer faculty and alumni include more than 145 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration.