This morning I was woken at the ungodly hour of 5:30am by drilling right outside my bedroom window. I live on a (semi) main road, but still lots of residential flats etc and it's very narrow. It's not emergency work - they are redoing the pavement the whole length of my road and the noise was from some sort of flattening machinery that compresses the bits underneath the paving slabs they lay later on (you can tell I know a lot about this stuff 
). So aside from the mechanical noise of the thing being switched on, it was also making a loud rhythmic thumping noise. Plus the engine of the truck next to it.
As I said, they are redoing the whole road so I can imagine there will be many more of these mornings in the future if I don't do something about it, but I looked at the council's noise complaints website and it said they don't accept complaints about roadworks! Surely there has to be a cut off point for when they can reasonably do this in a residential area?!