Another way that tank cars collapse like that is as a result of steam cleaning. The car is cleaned with steam, and the cleaner(s) neglect to leave the car unvented while the steam condenses, and pressure drops. And yes, they can collapse just that fast; as soon as the pressure differential drops below the correct threshold. You can reproduce the effect in miniature. Open a jar of your favorite salsa (I specify salsa because in my part of the world it's all still packed in glass) and heat the contents. Close the jar securely using the original lid. Let the salsa cool, and if you wait long enough, the "tamper evident" seal will pop to the sealed state.
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