It will be interesting to see how Peter’s data turns out and whether LED streetlights are generally a good or a bad thing. The fact that road lighting levels with LEDs are so much higher, even in residential streets, seems highly unnecessary to me and I don’t know if there is much we can do about it. There is also a problem for imagers in that the LED light is broadband and much more difficult to filter than sodium.
In Chelmsford many residential streetlights are turned off after 1am (it was midnight but the local, environmentally friendly, LibDems kicked up such a fuss that the Council changed the time). Despite the local paper predicting mass murder as a result (“Chelmsford returns to the dark ages…”) recent crime stats have shown a reduction. It certainly makes a big difference to my skies.