The trans siberian railway isn't high speed. There are plans to make some of it high speed but the only article I could find was from 2018 and at that time it was still only in the early planning stages and expected to cost billions of USD [0].

[0] https://www.railway-technology.com/features/moscow-kazan-hig....

(Edited to fix an autocorrect correction from my phone)

It certainly makes things more difficult. You need to clear tracks, build shelters where there is avalanche risk.