Parking Lot Lighting (12-20-19)

How can parking lot lighting help people in those lots at night feel safe?  Bullough, Snyder, and Kiefer investigated this issue, finding that “Previously published research has indicated that perceptions of safety and security under outdoor illumination are correlated with perceptions of scene brightness, which in turn are influenced by the light level in the lot, by the spectral distribution of the illumination, and the uniformity of illumination. . . . two laboratory experiments were conducted using a scale model parking lot scene and a controllable light-emitting diode (LED) lighting system that allowed parametric variations in light level, spectrum and uniformity. From the results, a mathematical model of overall brightness and safety perceptions was developed to predict how different lighting configurations are perceived.”  The model developed is detailed in this article.In brief: “Increasing short-wavelength output to leverage spectral sensitivity for scene brightness perception, and improving uniformity distributions will both increase perceptions of safety, but when a white light source (e.g. LED) is chosen, the magnitude of the spectral effect is relatively small compared to the impact of more uniform illumination.”

J. Bullough, J. Snyder, and K. Kiefer.  “Impacts of Average Illuminance, Spectral Distribution, and Uniformity on Brightness and Safety Perceptions Under Parking Lot Lighting.” Lighting Research and Technology, in press, https://doi.org/10.1177/1477153519875171