The £140m extension of the Docklands Light Railway (DLR) to London City Airport has officially opened.
More extensions to the line are planned
The new, 4.4km long section started carrying passengers on Friday.
The project was completed ahead of schedule and Mayor Ken Livingstone said it shows London's ability to deliver its commitments for the 2012 Olympics.
The airport is just two miles from the main Olympics venue in east London and will be a key part of the transport network for the Games.
The link means people can travel from the airport to Canary Wharf in just 14 minutes.
Mayor of London Ken Livingstone was joined at the opening ceremony by former athlete Colin Jackson, London 2012 chairman Sebastian Coe, Olympic gold medallist Denise Lewis and transport minister Karen Buck.
Mr Livingstone said the extension was "a vital new transport link which has been delivered on time and on budget".
Lord Coe said: "Having only last week agreed with the International Olympic Committee the key transport milestones towards 2012, this is timely and impressive evidence of London's ability to deliver on its promises.
'On our way'
"London will be ready to host an outstanding Games with progress on other key transport schemes already well under way."
Former champion hurdler Colin Jackson added: "When you see things like this being delivered, you think that we are definitely on our way."
More extensions to the line are planned. A station which will serve Woolwich via a link under the Thames is currently being built.
Plans to link the Canning Town branch to Stratford are being discussed as Stratford station will at the heart of the Olympic development.