Conflicting reports are shedding a new spotlight on light emitting diode (LED) streetlights, and Eugene civil engineers are paying attention. A recent guidance statement by the American Medical Association (AMA) argues blue-rich LED streetlights operate at a wavelength that suppresses melatonin during night and creates more nighttime glare than conventional lighting. However, the U.S. Department of Energy just released an article pointing out the issues are neither new nor restricted to LED technology.
The point of debate is the portion of the light in the “blue” spectrum, which the Department of Energy says can be roughly measured by correlated color temperature (CCT). Essentially, the lower the number the less “blue” light. However, at low CCTs, like the color of the conventional high pressure sodium bulbs, visibility can be distorted.
Public Works engineers just wrapped up a streetlight conversion project that led to the installation of nearly 5,000 LED fixtures, or about half of the City’s streetlights. As with any new information, they’re evaluating the statements from the AMA and the Department of Energy. Eugene engineers will also look into any new streetlight related research and monitor the reaction from cities across the country that also recently switched to LED lighting.
Part of the reasoning to replace the old bulbs came from a 2014 LED Streetlight Feasibility study. Engineers also looked at other cities that have recently moved to LED lights. They found people were more receptive to the neutral white lights that do contain some of the “blue” lighting.
Because LEDs are more efficient than the bulbs they’re replacing, the streetlight replacement project is expected to save the City $3.3 million in energy and maintenance costs over the next 20 years.