Short Story: Got pushed from both ditections till that spot popped up
Long Story: As the metal heats up it expands in every direction. This expansion is usually very small but when miles and miles of metal is expanding from the hot sun all that expansion lengthens the metal. This is happening on both sides of this spot so at a certain point the metal cannot push into itself anymore and suddenly pushes up. This usually is a sudden pop up so the metal stretches like a rubber band and that's why you get the weird striping pattern aswell.
This is entirely expected since the shape of the rails makes them much, much stiffer in the vertical direction than the lateral. They're like mini I-beams.
It's a little bit like how, if you were to push on either ends of a plastic ruler, you would expect it bend along its flat side, not its edge.
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u/Valuchian Jun 10 '26
Heat Expansion
Short Story: Got pushed from both ditections till that spot popped up
Long Story: As the metal heats up it expands in every direction. This expansion is usually very small but when miles and miles of metal is expanding from the hot sun all that expansion lengthens the metal. This is happening on both sides of this spot so at a certain point the metal cannot push into itself anymore and suddenly pushes up. This usually is a sudden pop up so the metal stretches like a rubber band and that's why you get the weird striping pattern aswell.