Why do ‘leaves on the line’ cause train delays, especially in autumn? The serious danger comes from a series of physics challenges: Leaves are sucked onto the tracks by the fast moving trains. The train wheels crush them into a slimy black pulp, releasing leaf oils that lessen friction. Mixed with rain, this super thin lubricant becomes more slippery than soapy water on the tracks.

From the BBC’s Bang Goes The Theory, Liz Bonnin demonstrates just how slippery it can get for a fast moving train (or even a not-so-fast moving train) on leaf-slimed tracks.

Related reading: A Leafy Curse – The Physics of Leaves on the Track.

File under: wheels, trains, autumn leaves, and physics.

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