The new lines will connect London and Birmingham, with connections to Manchester and Leeds.
"Once they are completed, London to the Second City would take just 45 minutes, while Manchester could be reached from the capital in only 66 minutes. It is regarded as the biggest transport system change since the building of the motorways half a century ago.
Around 12,000 jobs would be created - but work will not start until 2017, with the first high-speed trains by 2026. Routes to Scotland are also being considered."