South Bend Switching to LED Streetlights
The City of South Bend is giving residents a chance to weigh in on new LED streetlights, as reported by the South Bend Tribune. While the opportunity for input is welcome, responding residents should consider important issues like light color, glare, and brightness.
An online survey at southbendin.gov/led notes, "Nearly 50 streetlights have been converted from high pressure sodium to LEDs on local streets so the City can observe the changes in neighborhood lighting. The wattage and brightness is being tailored to the appropriate level for each type of street." The survey asks if the new lighting is an improvement, whether they're brighter, and whether they make you feel more comfortable. An open question asks for feedback on the level or quality of lighting.
Streetlights, like all outdoor lighting, should be full cutoff so light is not spread upward as waste. An image posted in the local newspaper suggests the new lights will be shielded well, provided they are installed level.
The color of new LEDs--labeled as a function of temperature in degrees Kelvin (K)--is an important consideration. The older sodium fixtures are far down the spectrum toward yellow at 2200K, while the newer LEDs being previewed are 3000K, which is much whiter. The 3000K light is at the higher end recommended by the American Medical Association, for blue-rich lights with their garish hue are considered a health hazard. The bluer light inhibits the human body's ability to produce melatonin, which suppresses some cancers, among other woes.
Manufacturers currently produce many streetlights at the 3000K level, which is certainly white, but residents in residential areas may prefer a gentler 2700K or 2800K streetlight if available. Many people welcome the bright white lights because they give a truer color of the objects they illuminate.
While the new LEDs are certainly more energy efficient and longer lasting, by virtue of being a higher temperature they will have a bluer hue. Blue light scatters more than red light, so a one-for-one swap of sodium lights for LEDs will inevitably yield an increase in sky glow. Any small correction (such as from the 3000K on display to a possible 2700K option) would impact the night sky less. That said, some gains will come from removing the sodium fixtures that spew random light sideways and upwards. The City should be commended if it does not install lights with sag lenses and prismatic lenses.
As you evaluate the City's proposed lights, remember what the light is supposed to do. It's intended to light up streets, not the facades of buildings and trees and clouds. Keep the illumination sufficient yet sensible. I look forward to seeing the fixtures in the City's sample installations and will weigh in later with my comments to the City.
For background on outdoor lighting issues in Michiana, see blog posts tagged "dark skies."
Update March 5, 2022:
Regarding the wattage and brightness being tailored to the appropriate level for each type of street, the City replied with this clarification:
Brightness varies by virtue of the differing watts, which are marked on the under side of the street lamp. The neighborhood streets have a slightly dimmer light at 68 watts, relative to, say, the brighter lights on Lincoln Way West corridor at 191 watts.
The color (suggested by degrees Kelvin) does not vary across the test installations, with all being the same color temperature of 3000K, which is likewise marked on the lights.