Passengers travelling on key Olympic routes endured delays today as a series of problems hit Tube and light railway systems in London.
The first snag came on the Underground's Jubilee line at North Greenwich station close to the Olympic site at Stratford in east London.
The problem, due to a fault with the platform-edge doors which are a feature of this part of the line, led to long delays on Jubilee services in the early part of the rush hour.
There were also minor delays today on another main transport route to Stratford, the Docklands Light Railway, due to a signalling problem at Canning Town.
Passengers using a third key Olympic route - London Overground - also endured rush-hour problems today.
This was caused by a signal failure at Canonbury which led to severe delays between Richmond and Stratford.
To add to the peak-time difficulties, the Underground's Central line was suspended between White City and Liverpool Street westbound due to a person under a train.
Later, services were able to resume on this stretch but there were severe delays on the line.
As the morning went on, travellers had to contend with more hold-ups.
Faulty track at South Hampstead led to no service on London Overground between Euston and Kilburn High Road.
On the Tube's District line there were delays between West Ham and Upminster due to a signal failure at Plaistow in east London.
With thousands of Olympic-related passengers continuing to arrive in London by air, the northern runway at Heathrow airport had to close for around 15 minutes so a runway light could be replaced.
Airport operator BAA said there had been no delays to flights.