Rail services to one of the key Olympic stations were delayed today, while there were also hold-ups at another major London terminus.
Some passengers were stuck for around 30 minutes outside London Bridge station due to "operating problems".
The difficulty, thought to be a signal problem, led to delays to services run by the Southern train company in and out of London Bridge in the morning rush-hour.
London Bridge is one of the major Olympic hub stations, dealing not only with arriving commuters in the morning but those leaving to go to Olympic events.
There were also problems at Cannon Street station where a signalling problem meant fewer trains to and from this main London terminus. This affected services run by the Southeastern train company.
There were also travel difficulties on the Tube today, with a signal failure at Turnham Green in west London resulting in no District line services between Earls Court and Richmond/Ealing Broadway.
A recorded message from London mayor Boris Johnson warning passengers of "huge pressure on the transport network" that was being played in London Underground stations and on buses has been discontinued.
A Transport for London (TfL) spokesman said it was not part of a new strategy and it was planned that the message would only be played for a certain time.
TfL said today that Tube passenger numbers were up by 7.5% on Monday compared with a normal Monday, with Docklands Light Railway up by a record 65%.
TfL warned that there would be road alterations today to cope with the Olympic road cycling time trials in and around Hampton Court and Surrey.
Olympic venues in use today include Horse Guards Parade, which means that central London will be busy.
TfL also said that the Tube's Jubilee line will be exceptionally busy in the early evening as events are taking place at Wembley, Lord's Cricket Ground, North Greenwich Arena, ExCeL exhibition centre in Docklands and the Olympic Park.
Baker Street, Kings Cross and Green Park Tube stations were expected to be very busy with spectators going to and from Wembley.