A new bright white LED streetlight made its debut in Dodgeville, Wisconsin on Friday, November 3, 2017, and it isn’t pretty.
The white-light LED streetlight is located at the NE corner of W. Washington St. & N. Johnson St. in Dodgeville. The illumination level on the ground peaks at 3.15 fc. An existing orange-light high pressure sodium streetlight at the SW corner of W. Division St. & N. Virginia Terrace peaks at 1.23 fc, which is typical.
Even though the reduction of uplight and near-horizontal light (i.e. “glare”) from this luminaire is a welcome improvement, an illumination level 2.6 times as bright as before is neither welcome nor justified. Furthermore, lower illumination levels may be acceptable when using white-light LED luminaires in comparison with high pressure sodium (Glamox n.d.). More research is needed on the effect of spectral composition on both brightness perception and, more importantly, visual acuity at various illuminance levels.
I do not have an instrument to measure the correlated color temperature (CCT) of this luminaire, but visually it looks to me to be around 4000 K, which is too blue. I will check with the City of Dodgeville and report back here. The International Dark-Sky Assocation (IDA) and the American Medical Assocation (AMA 2016) recommend using “warm white” LEDs with a CCT no higher than 3000 K, with 2700 K preferred.
AMA (2016), Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting H-135.927. Retrieved November 5, 2017 from https://policysearch.ama-assn.org/policyfinder/detail/H-135.927?uri=%2FAMADoc%2FHOD-135.927.xml.
Glamox (n.d.), The Glamox Brightness Sensitivity Test. Retrieved November 5, 2017 from http://glamox.com/gmo-recreational/led-brightness.
IDA (n.d.), LED: Why 3000K or Less. Retrieved November 5, 2017 from http://www.darksky.org/lighting/3k/.
Oesper, D. (January 9, 2017), Avoid Blue-Rich LED Lighting. https://cosmicreflections.skythisweek.info/2017/01/09/avoid-blue-rich-led-lighting/.