We've discussed sun kinks here many times before. The Tasmanian video likewise. It's still an interesting show, complete with at least one single-rail kink (looks like it broke the anchors).

I suspect that as climates become more extreme we will see more of this. Almost certainly, expansion joints like the ones mentioned above will be needed on the HSR line in the Valley where ground-level temps can range from near 10F on bad winter mornings (close to 0 in the mountains and high desert) to 130+ in the summer - and will go higher with "global" warming. Can't afford sun kinks where trains have to run 200+ mph; high-temp slow orders (railroads and rail transit often limit train speeds when temps go high, though for transit that can be due to wire tension concerns as much as track stability) would occur too often. In the US, expansion joints like the Swedish one shown are rare; we seem to rely on brute force and heavy track construction (with temperature adjustment when building the track) to hold things together.