Trains have been running up to two hours late because of leaves on the line, with Sussex one of the UK's worst-hit areas.
The regular autumn problem has come later than normal after an unusually warm October.
Leaves making the track slippery are a nightmare for train operators.
The 286 miles of South Central track through Sussex, Surrey and Kent are some of the worst affected in the country.
A spokesman said: "We had one service delayed for up to two hours yesterday due to leaf fall.
"Today we have had services delayed up to about ten minutes. If it drizzles there could be problems."
He said there could be delays for passengers in the coming few weeks.
Earlier this year, we accompanied train drivers on a skidpan training course near Horsham.
Rails were coated with a chemical similar to washing-up liquid to re-create the slipperiness of leaf-covered tracks.
Elwyn Roberts, operations manager of South Central, said: "Driving a train on a slippery line is like a car on an icy road.
"The travelling public may joke about leaves on the line but it is no joke for us."
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