I live fairly close to Heathrow and also the new rail link but rarely get any noise of any concern fortunately. Recently, last month or so I have noticed a banging sound in the middle of the night, not enough to wake me but just audible if I happen to be awake. It can go on for hours but not really a nuisance, I am just curious as to what it is. Pile driving was my first thought but the bangs seem only about 1sec apart which is not how I remember it. Any ideas.
A sensible suggestion tullie, I had not considered anything as simple as that. I have just checked my own recently fitted one which is bolted but still has some movement so I have wedged it now. I have a feeling you have hit the nail on the head (pun)
*A blow rate of an impact every second is not usual. *
That was my thought but I am not familiar with modern piling techniques.
As I said, it is not a nuisance and tullies suggestion sounded more likely until I found that it had been heard by others over a mile away.
Some kind of third party explanation was apparently rendered by the council saying it could not be done during daytime due to the tracks being used but that is only hear say.