Commuters are experiencing disruption this morning on Southern trains between London Bridge and Crystal Palace.
There are also delays between London Bridge and West Croydon, Purley and Caterham and Purley and Tattenham Corner due to signalling problem at Purley, and at Norwood Junction.
Tickets being accepted on London Midland services.
A signalling problem is causing further delays of up to 35 minutes and cancellations.
Earlier Norwood disruption also affects First Capital Connect and London Overground.
There are also severe delays between Sydenham and West Croydon due to signalling problem at Norwood Junction.
Tickets being accepted on local bus routes.