Permafrost as a track foundation

node · earth · Eastern Siberia and the Russian Far East

Perennially frozen ground behaves like rock until it is disturbed, and then behaves like mud. A ballasted railway insulates and warms the ground beneath it, thawing the active layer deeper each summer; the embankment settles unevenly, the alignment goes out of level and the track has to be relifted, sometimes annually. Almost half the Baikal–Amur Mainline sits on it. This is why the Amur route was harder and more expensive than the Manchurian shortcut, why the eastern Trans-Siberian took longest to finish, and why the maintenance cost of a northern alignment never stops — it is not a construction problem that is solved once but a permanent operating liability, now worsening as ground temperatures rise.