And over-lighting is just one lighting design practice that can disturb the surrounding environment. By rethinking the overall scheme for a road, a lot of ecological issues can be resolved. Let's look at the city of Cambridge, MA and University of California (UC) Davis, both of which have implemented adaptive lighting strategies using LEDs. In Cambridge, street lights dim to 50 percent at dusk and to 30 percent of the total light output from 10 p.m. (8 p.m. in some neighborhoods) to sunrise. UC Davis, installed about 1,500 intelligent LED street lights that can detect when there was activity on a road. When the street is empty, they operate at 10 percent of the total light output. Upon detecting a car or someone on an evening walk, the lights brighten to 80 to 90 percent of capacity. Both Cambridge and the UC Davis have reported energy savings of over 80 percent. When Tucson, Arizona implemented similar strategies, its night skies became darker, according to the Dark Sky Association.