Tube passengers were warned today it could take more than half an hour just to get on a train at key stations during the Olympics.
Stations which will be among the busiest include Waterloo, London Bridge and Bank
Transport for London (TfL) is sending texts to passengers who have registered to receive the information service warning of delays.
Waterloo, says TfL, "will be exceptionally busy during the weekday peak hours.
"Waiting times to board trains are expected to be longer than 30 minutes on certain dates and at certain times."
It is sending out the same message about other key stations.
Delays could take much longer at busy mainline rail interchange stations.
The TfL information applies only to the Tube section and does not include mainline rail.
The busiest day at London Bridge is going to be next Monday, 30 July, fuelled by visitors heading towards one of the most exciting events of the Games; the equestrian individual and team cross country at Greenwich Park. They will use the station to travel two stops to Greenwich on the mainline or the Jubilee line to North Greenwich and then a walk or bus.
TFL is strongly advising other users to stay from from London Bridge on Monday when a record 273,000 passengers are expected to travel through. That's an extra 69,000 on top of the usual daily 204,000.
Transport chiefs say the station is just "not designed to cope"with the huge volume of people. If possible commuters should try and avoid the station for the duration of the Games.
To make matters worse Olympic visitors will in the main be travelling against the normal rush-hour flow. Because of this, for Monday only, you will not be able to enter the station to board trains travelling from platforms 1-6 - Southeastern and First Capital Connect services between 6pm and 10 pm.
Bank station should also be avoided at busy times with commuters instead advised to switch to the Central and or Docklands Light Railway.
Details of every Tube station along with the dates and times of when each will be at its busiest are available on the TfL website getaheadofthegames.com
