Mark Brader wrote:
Brad Chapman:
When I am at Turnham Green, I have noticed that the tracks make
strange noises when either a Piccadilly or a District train is
approaching [or leaving]. ... the tracks twang, rattle and vibrate
like huge springs are being snapped back and forth.

Does anyone have a clue as to what I'm hearing?

On some parts of the Toronto subway system, oversize concrete sleepers
are used. These are so wide that they form almost a continuous sheet
of concrete with only small gaps between them, and although the rail
fastenings are spaced as usual, each rail is fastened to each sleeper
in two places. I have heard that between these sleepers and another
layer of concrete underneath, there is some sort of rubber; I don't
know in what form exactly. And this track makes sounds very much like
Brad's description, except that I would have omitted the word
"rattle".

So do the tracks around Turnham Green *look* any different than on
other parts of the Underground, these days? It's been some years
since I was there.

They are normal LU bullhead rail on wooden sleepers. I'm familiar with the
noise (it's my local station), but I've never regarded it as abnormal. I
think you'll find it occurs at any location in the open with a stretch of
plain line (no points). I can't think of another station where I hear a
similar noise, but that might just be because the other stations where I
wait for trains are either in tunnel or where there are points which would
prevent the sound being transmitted from a distance.
--
Richard J.
(to e-mail me, swap uk and yon in address)