In Europe, Philips in the '50's introduced Natrium lights for streets and highways. This orange 'single spectrum' light has 2 big advantages: (1) low electricity usage and (2) the human eye does not get night blinded , because the orange light only triggers the cones in the eyes , but not the rods. That's why BMW had 'orange only' display in their cars for decades. (This knowledge has been lost on newer generation of car engineers ).