Actually since our curves are much tighter than the prototype, and our ballast and subroadbed is often inferior to the real thing, we have MORE issues than the prototoype.
I have INDEED seen heat kinks here in the USA, and not just Nevada and Arizona. SplitJaw makes special expansion tracks for this problem.
I've seen track move over 1/2 inch in curves in each direction.
The physics is the same in our scale and the prototype. Our trains can actually tolerate greater "inaccuracies" than the prototype, but it all is the same laws of physics.
Indeed, as suggested earlier, I have a friend that was a Roadmaster on a railroad, and then worked for the FRA as a track inspector. He taught me a lot about the prototype, and applying those things to my layout increased my reliability greatly.
The topic of fixed vs. floating rails will NEVER be settled, just like letting rails slide in the ties or not. When I started in G scale more than 10 years ago, the "popular" thinking was fasten everything down, now the popular thinking is free floating track in ballast.
Different techniques work for different people in different climates. I have had the most sucess with free floating, and the least maintenance.
Greg
Our layouts are very short compared to the real thing. the track just adjusts itself a bit - maybe at the corners - and all is well. I cant remember ever seeing a heat induced kink on a G scale layout. Also, of course, our rails are well over scale.