Track movement under freight train

[tetters]

I say a little bit of give is necessary with any kind of structure that has to bear heavy, immense structural loads. Even the CN tower (like most modern building structures) made out of solid concrete and rebar was/is designed to sway ever so slightly in the wind in order to increase its "life expectancy" as a structure. Something solid, rigid and immovable would wear out faster, collapse or break when subjected to constant forces impacting on its structure.

I'm probably just pointing out the obvious to everyone here.