Thousands of rugby fans are at Waterloo making the trip to the Twickenham opening of the World Cup. The station is on the line to Windsor and Reading.
Regular passengers were asked to consider changing travel during the rush hour to avoid crowding.
While Waterloo is extremely busy, services and the flow of passengers is working well.
Many appear to have heeded the travel advice.
Rail disruption at Eastleigh in Hampshire is expected to last until midday. An earlier incident involving a non-passenger service in Eastleigh led to a train blocking a set of points.
Thank you for your patience and understanding, lines have now reopened. Apologies for the disruptions. Update:http://t.co/hhAhQnBTyo
Commuters hit by long delays on South West Trains services into London Waterloo this morning have been re-acting to a tweet thanking them for their patience.
Long delays are expected until lunchtime due to signalling problems between Wimbledon and London Waterloo.
@sw_trains there's still no trains out of Waterloo and thousands waiting on concourse for news. Don't be tweeting like it's all fixed now!
Commuters in the Thames Valley have been warned they will have to deal with disruption for several hours during the morning rush after a signalling problem on a busy railway line into London.
Passengers could be delayed by up to an hour as a result of a problem between Wimbledon and Earlsfield which sparked cancellations on services into and out of Waterloo.
The signalling problem between Wimbledon and Earlsfield has now been resolved and trains are now able to run to and from London Waterloo via Wimbledon.
However, we expect there will be knock-on disruption for several hours. Delays of up to 60 minutes to journeys are expected until services fully return to normal.
There's disruption on South West Trains between Basingstoke and Woking due to flooding at Farnborough.
Trains are unable to call between Winchfield and Brookwood.
The firm says there is no estimate for when a normal service will resume.
Replacement bus service running on South West Trains between Alton and Farnham due to emergency engineering works.
Buses are replacing trains between Alton & Farnham, extending journey times by up to 20 minutes.Buses will not be calling at Bentley, passengers will be provided with taxis instead. Disruption is expected until 11:00.
Delays of up to 50 minutes on South West Trains between Bournemouth and Wareham due to trespassers on the line.
Possible disruption on South West Trains between Portsmouth Harbour and Havant due to emergency services dealing with an incident. Train services running to and from these stations may be delayed or revised at short notice. An estimate for the resumption of normal services will be provided as soon as the problem has been fully assessed.
South West Trains have apologised for an announcement urging fat people to stay on their feet due to overcrowding.
The train was full of commuters when a member of staff reportedly said: 'We are going to be like sardines on this train, so can I ask that only slim people sit on the three-seaters.
'If you are fat then it is simply not going to work.'
One angry passenger on the service, which was leaving Basingstoke in Hampshire, told the Daily Mail: 'I am not necessarily a big person but most people are larger than those seats anyway. It's pretty disgusting. I would get fired if I said that at my work.'
South West Trains have since apologised, saying the comment, if it had been made, was unacceptable.
A spokesman said: 'All passengers are welcome on board our trains and we would find it unacceptable if that comment had been made by one of our employees.
'We run some of the busiest trains in the country and we do appreciate that space on some of our trains is limited.
'To provide extra space and seats for our customers, we are in the process of investing £250m in extra carriages and new trains.'