As regards light pollution, I'd have thought PIR detectors on street lights the best way of reducing it. With LED lights which can be switched on or off in nanoseconds replacing sodium discharge lamps which take minutes to warm up, it is feasible and will save money.
Why light up a suburban road or a motorway all night when there is nobody on it?
I used to stay regularly in a rather charming village in Bucks. All the houses were thatched, and there were no street lights at all. Eventually, the Parish council got them put in, but people disliked not being able to see the stars, and the rate of burglary shot up! Previously, darkness had made it difficult for them, and using torches would have made them stand out. The new illumination made it a lot easier for them. After a few months, the lights were all switched off by the villagers opening them up and removing the fuses, and the village reverted to darkness again.