Thousands of rail passengers commuting into London faced delays today after signalling problems near London Bridge.
Blown fuses disrupted journeys into the city from the south and some services were cancelled.
Services on the Brighton Mainline, Metro, Redhill, Mainline West and Mainline East were affected, Southern Railway said.
A spokesman for Network Rail said the problem began at 5.30am when fuses blew at Honor Oak Park station.
He said: "It took a little time for services to get back to normal, but they are running as normal now. There were some diversion routes available."
Chris Hudson, a spokesman for Southern Railway, said: "Network Rail are telling us the problem has been corrected, but because of the time of day it happened and the amount of trains we had going in, although it has been fixed there are residual delays."
Mr Hudson said he expected Southern Railway trains would be affected until about 11.30am.
London Bridge is expected to be one of the busiest rail stations during the Olympics.
As well as receiving commuters travelling in to work, London Bridge will be the departure point for many thousands attending Games events.
Today's problem near London Bridge also affected services on the London Overground.
It was the third day running that commuters had been hit by rush-hour delays. Earlier this week there were long delays on the Bakerloo, Circle and District lines, with the Bakerloo line being part-suspended on Tuesday morning after a fire alert at Charing Cross Underground station.
Later, in the heart of the morning rush-hour, service clockwise on the Tube's Circle line was suspended due to a signal failure at South Kensington in west London.
Also, main line services run by the Southeastern train company were delayed in south London due to a signalling problem near Dartford.
Later, there were severe delays on the section of the Underground's Piccadilly line serving Heathrow airport in west London.
A person under a train meant there were lengthy hold-ups between Acton Town and Heathrow and between Acton Town and Uxbridge.