Up to 100,000 mainline rail communters and Olympic visitors using London Bridge - a Games "hotspot" station - faced major disruption again today after taking hours longer than usual getting home last night.
Commuters were warned there could be more problems getting home again tonight if engineers are unable to repair s signal fault - cause of last night's problems - in time for the evening peak.
And there was more major trouble on the Tube with thousands delayed when the District line was part suspended just as the morning peak was building to maximum.
Trains were halted between Earl's Court and Richmond and Ealing Broadway.
This was due to a signal failure which happened just before 7.30 am at Turnham Green.
The District is one of the busiest routes on the network and used by more than 650,000 people a day.
There were problems too at London Bridge last night after the signals failed at 5pm - just at the start of the commuter exodus from the Square Mile and Games visitors were returning from watching Zara Phillips and Team GB win silver in the three day event at Greenwich Park
Many trains from Greenwich and across south east London and Kent heading into Cannon Street were forced to stop short at London Briidgeand evacuate passengers at London Bridge, adding enorously to the problems.
On Monday commuters and Games visitors were warned to avoid London Bridge at all costs because thousands heading to the Park would clash with commuters.
But everything worked perfectly, commuters said they had good journeys and rail bosses were giving themselves a cautious pat on the back.
Last night it all went dramatically wrong when the signals failed. Huge queues immediately built up outside the station - used by more than 200,000 people a day under normal circumstances.
Network Rail (NR) engineers worked through the night but were unable to restore a full service.
Commuters and Olympic visitors were warned that between 8 am and 10 am there would be;
*fewer trains in and out of London Bridge - meaning delays for those heading to the women's 25m pistol final at Woolwich Barracks.
*Trains diverted to start start or terminate at Victoria;
*Passengers advised to use the Tube or Docklands Light Rail (DLR) instead where ticlkets would be accepted.
More than 100 trains were affected during the worst of the disruption which lasted until 7 pm but severe delays to Southeastern services continued throughout the rest of the evening.
Busy Cannon Street, one of the main stations serving the Square Mile, was virtually closed with only a few trains able to get in and out.
Greenwich Park visitors, having enjoyed all the thriils of the equestion events, were told to avoid Greenwich mainline station and use the DLR instead.
Commuters were wraned not to try and use Cannon Street and travel by Tube instead to Charing Cross and Victoria.
As humour still broke through.
Darren Bell Tweeted at 6 pm - height of the problem - "Anyone need platform 1-6 at London Bridge don't bother. Go to pub. It's carnage."
GS Stringer wrote: "I urge all visitors to London to go to London Bridge and partake in a great British tradition."
Bruce Arthur voiced "London Bridge has now actually fallen down."
An NR spokesman said the original fault happened at the Borough Market junction, one of the busiest on the network and where trains pass every few seconds during peak times.
An emergency "standby" team of engineer troubleshooters - one of the suads on hand to react immediately throughout the Games period - was on site "within minutes.
"They worked through the night and repaired theoriginal fault but in doing so found another one."
The spokesman said he was unable to say when repairs would be completed. If not, one option being studied is to again run a reduced service from Cannon Street this evening and carry out more repairs overnight.
"We apologise profusely to passengers and Olympic visitors for all the disruption they suffered last night and this morning.
"Our engineers really are doing their best to get services back to norma," he added.s
A Southeastern spokeswoman said: "A very large number of our trains were either diverted, cancelled or stopped short of their scheduled destination.
"This created huge problems last night for which we apologise."
The District line disruption caused major problems for those heading to Earl's Court and the volleyball events which began at 9.30 am.
Visitors were advised to use the Piccadilly line instead.
The rush hour is now starting much earlier than usual on the Tube with many commuters aiming to beat the Olympic crowds.
Many Jubilee line services were standing room only from 6 am.