Anybody a regular passenger of the Piccadilly Line on the non-stop
bit from Hammersmith to Acton Town? Why is the ride so bumpy?
Sometimes it feels like the carriage is going to derail! I don't
remember it being like that before..

The track is falling to pieces and needs to be rebuilt. Metronet is
_supposed_ to begin replacing it in 2005.
If you look at it you'll see how poor-quality it is in some places.