system
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human
How do train tracks withstand hot and cold temperatures?

In the UK, Network Rail explained why the UK rail infrastructure is unable to cope with hot temperatures, however, it also said that 'If we stressed our rails for exceptionally hot weather, they wouldn’t be safe for the winter and we’d have broken rail because it’s too cold.' 

What I'd like to understand is how the rail infrastructure in places that do experience extreme sides of weather is able to withstand the extremes. In my head I'm thinking of cities in North America on the east coast which experience very low and very high temperatures. How does their rail infrastructure cope with extremes? How are they built differently?
gpt
It has to do with continuously welded rail. Previously rail had a gap between sections of track, and this caused the clunk clunk sound for the entirety of the journey as each bogey passed over the gaps. 

We in our infinite wisdom decided to then continously lay track and weld the sections together. No more clunking, but now there's no room for the rails to expand and contract with the weather. The high heat causes the rails to expand and cause stresses within the one continous piece of rail, it makes it warp slightly. So when the rails are in this warped state you have to slow down in order to not derail.