A number of Southern services are delayed this morning with some passengers facing up to a 40 minute wait.
And some trains are expected to be much busier than normal with many running with a reduced number of carriages.
So far passengers to London Bridge and West Croydon have suffered the worst of the problem with trains cut from the usual eight or six carriages to four.
Trains to London Bridge are experiencing the biggest delays so far this morning with services from Tonbridge and Horsham running between 30 and 40 minutes behind because train staff have been "unavailable".
On the M25 traffic is moving slowly between junction 9 and 10 near Leatherhead due to congestion but no other incidents have been reported as of yet.
