A question on Quora asked whether railroad tracks had to be bent in the factory before laying, or heat-treated on site to bend them. A real railroadman gave the astonishing answer.
Neither! Rails bend easily to the curve needed for regular tracks. The much sharper curves of a streetcar line might need heating.
Here’s a video of a track being laid. Start around 10 minutes. You can see it’s not heated; it just slithers back and forth on its own!
I always made the same assumption as the questioner. A 4×4 wooden post doesn’t bend over the length seen in this video, so I figured a steel rail would be a whole lot stiffer unless heated to soften.
Polistra's Mill 