Officials tackling leaves on the railway lines this autumn have insisted the seasonal problem is "not a joke".
A mature track-side tree has up to 50,000 leaves
Longer journey times have started this week as South Eastern Trains builds delays into the timetable so passengers can know when their trains will arrive.
The "leaf fall timetable" will be in place until the summer schedule begins.
"Autumn is a season, but leaves don't necessarily fall all at the same time," a spokeswoman said. "So we are very much dependent on the weather."
The winter timetable shows adjustments in leaf-fall blackspots such as on the Hastings line, where trains are leaving three minutes earlier.
"It is so that passengers have a better understanding and so they know when the train will arrive," the spokeswoman said.
KEEPING THE LINES CLEAR
Vegetation is cut back from the line side
Lines are cleared with high-powered water jets
Leaf-catching fencing and netting is put up
Gritting paste is laid to improve adhesion
"We can say, from past experience, we will do whatever we can but delays will happen, so they are built in.
"It is a bit of a national joke but it is a problem for the railways and it becomes a problem for our passengers, so it isn't a joke for us."
According to the rail operator which provides train services in Kent and Sussex, the problem occurs when seasonal conditions lead to poor rail adhesion.
Fallen leaves driven over by trains become like a hard resin, or the equivalent of black ice for cars on the road.
And when track conditions are poor, drivers have to slow trains down sooner for stations and signals, and also move off more slowly.
South Eastern Trains said work takes place all year to keep vegetation under control.