Transport for London and the London Mayor have announced details on the new Crossrail trains due to go into service in 2017.

The trains should be the most advanced on the London rail network so far. They will feature free Wi-Fi for all passengers and there will also be access to 4G.

TfL says the trains will consist of nine walk-through carriages capable of holding up to 1,500 tube users thanks to their 200 metre length. That makes these one and a half times longer than the current longest commuter train.

The new trains are engineered from lightweight materials like an aluminium body shell making them more efficient. Regenerative braking will make sure no power is wasted. The result is a train that is light enough to use 30 per cent less energy than old trains while still being faster.

Real-time travel information will be fed into the train's digital information system that is visible from throughout the train.

Mayor of London, Boris Johnson MP, said: "It’s fantastic to think that these sleek new trains will soon be transporting millions of people across our great city and beyond. They’re feature packed, eye-catching machines that showcase the best of British design and engineering."

Crossrail is due to be fully operational by 2019.