Leaf tannins dissolve metal in train tracks, which reduces friction between steel surfaces. Leaves on the line are a notorious headache for commuters and train companies alike, causing costly delays. Now scientists say they have unpicked why fallen foliage makes rails so slippery. When leaves are crushed against the tracks, they form a black layer that drastically reduces friction between train wheels and the rails “ a situation Network Rail has described as 'the black ice of the railway'. But the make up of this slippery layer has been something of a puzzle.
Leaf tannins dissolve metal in train tracks, which reduces friction between steel surfaces