The three-carriage driverless trains will run on the automatic Docklands Light Railway (DLR) system through East London ready for the 2012 Olympics at Stratford.

Ken Livingstone was joined by John Armitt, chairman of the Olympic Delivery Authority, and Dean Macey, Commonwealth Gold medal winning decathlete and Beijing Olympic Games medal contender, at the unveiling of the fleet of 55 carriages.

The Olympic Delivery Authority and Transport for London have invested £100m in the new carriages which are set to deliver a 50% capacity increase by 2010 and will play a key part in transporting the millions of spectators expected to attend the London 2012 Olympic Games and Paralympic Games.

During the 2012 Games the Docklands Light Railway will serve the main Olympic Park at Stratford, as well as competition venues at Woolwich, Greenwich and ExCeL exhibition centre.  The rail carriages will operate along the existing DLR network, as well as new routes to Woolwich Arsenal and Stratford International.

Delivery of the carriages will continue to take place until next year.  After testing has finished the first vehicles will be operational this spring with the remainder introduced into service up to the end of 2009.

Ken Livingstone, said: "Delivery of these new trains is great news for passengers today, and for the passengers of the future.  They're modern, they're spacious and they demonstrate once again our commitment to delivering a world class transport network on time and on budget that will serve the 2012 Games and provide a much improved service for Londoners."

At first passengers will see the new carriages, which boast a sleeker design and increased window space, running alongside the existing two carriage trains.  But they will begin to form three carriage trains when platform extensions have been completed.  The first platform extensions are already being made to the Bank-Lewisham branch, which will be completed by 2010.

John Armitt, chair of the Olympic Delivery Authority, said: "Transport is a crucial element to London 2012, and the Docklands Light Railway will be essential in moving hundreds of thousands of people to and from the Olympic Park during the Games. Transport for London has proved again that they are on track to deliver the necessary transport improvements to make the summer of 2012 run efficiently and effectively."