No-wonder our 66's shake about over that bit.
Would hate to see a video of a train down that,think i might slow down!!
There is nothing unsafe with the track there, but from a track engineering point of view there are the makings of various types of track defect, and I believe at least two that would be felt.
The short lengths of UK freight trains would not represent a problem running over track such as that where there is a distance between the various geometry changes but on a heavy haul line where trains can be up to three miles long, such track conditions will set up a lot of unwanted vehicle dynamic responses at speed which ripple through the train and cause a rapid deterioration to the track and its formation over time.
I work abroad and we have had cases where the dynamic response generated by even a relatively poor track geometry has resulted in the wheel flanges striking the crossing nose in S&C and hammering it to pieces. The resultant damage to the wheel tread caused the wheel to fail and the best part of 35,000 tonnes squeezed the wagon into a cube when it dropped off in the S&C at 80.
I would imagine you are experiencing sway and bouncing, with the occasional lateral "kick" ?