The Government launched a "fightback" today over controversial plans for the HS2 rail link, promising a £15 billion boost to the economy.
Transport Secretary Patrick McLoughlin promised to "squeeze every penny" of economic benefit out of the project as a new analysis concluded it would be worth £15 billion a year by 2037.
The Transport Secretary said there was no point "patching up" existing infrastructure, arguing it would not deliver the same benefits as a new high-speed line.
He added that the extra capacity was needed to give a "heart bypass" to the "clogged arteries" of the existing transport network.
Ministers are attempting to bolster support for the train link, which will connect London with Birmingham, Leeds and Manchester, after it was heavily criticised by the Public Accounts Committee.
MPs on the Commons spending watchdog issued a scathing report on the scheme this week, warning that the apparent benefits were dwindling as the costs soared.
Mr McLoughlin admitted it would be "absurd" to claim the scheme was perfect and ministers promised to "adapt and improve" the plans in response to criticism of the project.