anna parciak Getty Images/iStockphoto
Warning lights
Warning lights can enhance safety but also pose risks, research finds.Photo by anna parciak/iStockphoto.com
Warning lights and beacons are standard equipment on all types of service trucks, but their proper use does not totally eliminate the dangers workers face from drivers of other vehicles.
In fact, studies have shown that U.S. workers in the construction, transportation, and utilities sectors are over-represented in work-related injuries and fatalities, many of which involve motor vehicle crashes.
Given this, the Rensselaer Polytechnic Institute in Troy, N.Y., has partnered with the National Institute for Occupational Safety and Health (NIOSH) in a four-year project to more closely investigate the properties of warning lights and how they relate to worker safety. The fruits of that effort include a recent paper, titled “Intelligent Warning Lights and Driving Safety,” by Dr. John Bullough, an adjunct faculty member and the director of transportation and safety lighting programs at the institute’s Lighting Research Center. That paper offers suggestions on how the use of warning lights and beacons can be improved on service-related vehicles by addressing things like maximum luminous intensity, modulation characteristics, and the number of lights used.
“This issue has been studied in piecemeal over many decades, but our project is one of the first attempts to systematically investigate how lights can work together to provide information to drivers to help worker safety,” Bullough explains.
Brighter not necessarily better
The importance of (and need for) warning lights and beacons on service vehicles is not in question, but Bullough points out that getting the attention of other drivers is only the first job of these lights. He explains that all lights on service vehicles need to have a certain intensity level to adequately warn other vehicles of their presence. But the use of brighter, more intense lights may actually make it more difficult for other drivers to navigate through an incident scene on the roadway. That in-turn can make workers less safe by creating glare and/or a scenario that Bullough describes as “visual chaos.”
Dr. John Bullough
“This issue has been studied in piecemeal over many decades, but our project is one of the first attempts to systematically investigate how lights can work together to provide information to drivers to help worker safety.”Dr. John Bullough, director, Lighting Research Center, Rensselaer Polytechnic Institute
“Twenty years ago, meeting the lighting standards for service vehicles was a challenge,” says Bullough, adding that the study’s findings have been presented to various industry associations and boards, as well as the New York State Department of Transportation. “However, there is more energy and light to spare thanks to advances in lighting technology. So there is now a potential for overkill by making lights too bright.”
The Society of Automotive Engineers, a.k.a SAE, actually publishes standards on the required intensity, color, and flash rates for warning lights. However, Bullough says there are other things these standards do not cover, such as an upper limit on intensity to control for glare, or how multiple lights can be coordinated to help eliminate confusing and distracting environments that can negatively impair other drivers.
“Basically we found that peak intensities of warning lights should approach 1,000 candelas to make sure they can be detected in the daytime in complex urban environments, but this may be too high for nighttime conditions when they can create glare. This is especially the case when there is fog, or snow, which makes glare worse,” explains Bullough, who says the researchers also discovered it is easier for other drivers to judge distances and slow down sooner if warning lights flash in a high/low pattern, as opposed to an on/off pattern. “We are also learning that when multiple lights are used, flashing them in-sync, or in a sequenced pattern can be helpful, as it helps give drivers better guidance on what to do.”
More trials coming
The study, now in its third year, is transitioning into more field trials that will include at a test track at Penn State University. Even though Bullough says no lighting standards have been re-written yet as a result of the work, he hopes the results of the experiments will eventually help end-users adopt practices that create safer work environments.
“We do not want this information to sit on a shelf and not get used,” Bullough says. “This is why we want to come up with solutions that are doable and practical for people in the field.”
Mark Yontz is a freelance writer from Urbandale, Iowa.
