HE CUT THE TRACKS?! Why Train Tracks Have Gaps in Between
Animated Short, 0:53. Published 2026-11-08.
Why do train tracks have gaps in between? Steel grows in summer heat, so old jointed rails needed room, or the track would buckle.
True bits: US rails came in 39-foot lengths, sized to fit 40-foot gondola cars. A 39-foot steel rail grows about a third of an inch from winter to summer, and track laid with gaps was set so they barely closed on the hottest day. Heat buckles are called sun kinks. Today's welded rail has no gaps: it's anchored stretched at a set neutral temperature.
Cover photo: buckled rails on the Yarra Valley Railway by Lankyrider, Wikimedia Commons, CC BY-SA 4.0.
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Transcript
He sawed gaps into the train tracks. Every thirty-nine feet. Two companies race across a canyon. First one done wins. His boss is furious. You're ruining my railroad! But he won't close a single gap. The other crew lays perfect rails, end to end, and finishes first. Their trains glide in silence. His go clickety-clack.
Everyone picks the quiet line. Even his boss. Then summer comes. His gaps shrink. May, a coin fits. July, a sheet of paper. Then, the hottest day. His gaps finally close. And the perfect line starts to bend, like a snake. With a train coming. Steel grows in heat. About a third of an inch per rail.
The gaps gave it room. Today's rails are welded and locked down stretched, so heat can't bend them. But back then, steel needed room. That's why
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