Despite pledging to find savings in the expensive High Speed 2 train line, the project's boss has failed to find significant financial cuts.
The Government has been accused in the Supreme Court of "cutting corners" to push through the HS2 national high-speed rail project.
The Government has hailed a "landmark victory" for its HS2 high-speed rail scheme, despite legal flaws in the consultation process.
The consultation period for the environmental statement of the HS2 high-speed rail project - which is to connect London with Birmingham, Manchester and Leeds - has been extended by an extra 17 days following a ruling by a Commons committee.
Opponents of the £50 billion scheme wanted an extension after 877 pages of documents were initially left off a computer memory stick.
The House of Commons Standing Orders Committee said on Wednesday that the consultation period, due to end on January 24, should be extended until February 10.
Former Welsh secretary Cheryl Gillan, whose Chesham and Amersham constituency lies on the route of the first London to Birmingham phase of HS2, said she was sure campaigners and environmental organisations would welcome the consultation extension.
Stop HS2 campaign manager, Joe Rukin, said this was the first time the Standing Orders Committee had had to be called in six years.
Controlling HS2 costs and delivering the project quickly are vital for its success, according to the new chairman of the £50 billion high-speed rail scheme.
Not going ahead with HS2 would be "disastrous for the whole nation" said HS2 Ltd chairman Sir David Higgins today.
Acknowledging the opposition that exists for the project, Sir David said that major new schemes were always challenging as they produced change.
Sir David , who has been Network Rail chief executive, said it was vital that the UK had a railway fit for the 21st century.
A new high-speed line would deliver the extra capacity vitally needed on a network suffering from "ageing infrastructure", he said.
Work on the first phase of HS2 is due to start in 2017 with completion due in 2026. A second phase, taking the line to north west and north east England in a Y-shaped route, is expected to be finished by 2032/33.
It is expected that HS2 will create up to 2,000 apprentices during the lifetime of construction. Also, it is thought the college will open in 2017.
The cost of the entire project is currently £42.6 billion, with a further £7.5 billion for the high-speed trains.
Shadow chancellor Ed Balls insisted last year that there would be "no blank cheque" from Labour for the project.
Plans for a new college to train the next generation of top engineers to work on the construction of the £50 billion HS2 high-speed rail project - which will link Leeds with London, Manchester and Birmingham - have been unveiled by the Government.
Announced by Skills and Enterprise Minister Matthew Hancock, the new college will deliver the specialised training and qualifications needed for high-speed rail, which will benefit HS2 and other future infrastructure projects across the country.
It will offer the necessary technical training, including rail engineering, environmental skills and construction to make HS2 a success and ensure it can be built by skilled British workers.
It will be the first new incorporated Further Education College in over 20 years.
It is expected that HS2 will create up to 2,000 apprentices during the lifetime of construction. Also, it is expected the college will open in 2017, the date for the first London to Birmingham phase of HS2 to begin.
The first phase is due for completion in 2026, with a second phase, taking the line on a Y-shaped route to north west and north east England, due to be finished in 2032/33.
It is "essential for the UK" for the HS2 high-speed rail project, which would run between London and Birmingham and the North to go ahead, a report by MPs said.
The risks of not going ahead with the project "significantly outweigh the risks of doing so," say the House of Commons Transport Committee.
The committee, chaired by Louise Ellman, Labour MP for Liverpool Riverside, also said serious thought should be given to building the second-phase northern section of the line at the same time as the first phase London-to-Birmingham stretch.
The report into the viability of HS2 is a "cheerleading whitewash" and only heard from "people who support" the London to Birmingham rail link, according to activists.
Campaign manager for the Stop HS2 group Joe Rukin said:
– Stop HS2 campaign manager Joe Rukin
Unlike the public accounts committee and treasury committee hearings on HS2, it was clear that this inquiry was going to be a cheerleading whitewash when the transport committee only called people who support HS2 to give evidence.
Despite the official cost of HS2 standing at £50 billion, the committee want to pretend it is £28 billion, even though they said it would be £34 billion in 2011.
In saying this and telling the DfT they should abandon their standard assessments to improve the case for HS2, they are effectively ordering the Government to 'spin harder' on HS2.
HS2 will deliver "the step change in capacity" needed to support growing demand from both passengers and freight, according to the head of the transport committee.
Chairwoman Louise Ellman said if taxpayers were to reap the full benefits of HS2, it was "vital" links were improved between regular and high-speed rail networks.
– transport select committee chairwoman louise ellman
We remain confident that construction of a new high speed line is the only way to deliver the step change in capacity on the West Coast Main Line needed to accommodate long-term demand for both passengers and rail freight.
If we are to spread the benefits from HS2 as widely as possible, it is vital we improve links between the conventional and high-speed networks and bring forward projects to speed up journey times on the conventional network.
One bone of contention for anti-HS2 campaigners has been the cost of the project, with the Taxpayers' Alliance dubbing the project a "white elephant".
In June the transport secretary told the commons HS2 would go £10bn over the original budget of £33bn to cover "contingency costs".
- The projected cost of the whole projects is now £42.6bn
- A total of £7.5bn needed for the purchase of high-speed trains.
- £14.56bn of the overall cost will be set aside for contingency costs.
A group of MPs are "convinced" the controversial HS2 link between London and the north is "justified" and urged the Government to consider building the second and first phases together.
Abandoning the project "significantly outweigh the risks" of building it, as the high-speed rail link is "essential for the UK", according to the transport committee.
Phase one, from London to Birmingham via the Chilterns, is due for completion in 2026, with a second Y-shaped section from Birmingham to north-west and north-east England due to be finished in 2032/33.
In its report, the committee said: "Many important local issues will be debated and resolved by the (HS2) hybrid bill committee and there will be detailed debates about many aspects of the project.
"However, we are convinced that it is essential for the UK for HS2 to go ahead, and to do so as a project which has the backing of all three major political parties."
David Cameron has promised China's leadership that there will be "very open competition" for investments in Britain's HS2 high-speed rail link which would link Yorkshire to London.
The Prime Minister said he made the pledge during talks in Beijing with President Xi Jinping and Premier Li Keqiang, who expressed an interest in putting Chinese money behind the controversial project.
His comments came during a question session at Shanghai's Jiao Tong university where Mr Cameron stressed Premier Li's characterisation of Britain and China as "indispensible partners" as an indication of the deepening bonds between the two countries.
He explained to students why the Government is having to fight to build one high-speed rail line, while China has successfully completed 6,214 miles (10,000km) of track.
The government today published the official bill detailing the route HS2 will take. It is 50,000 pages long and details a route across hundreds of kilometres of countryside
But the document was greeted by protests outside parliament, where campaigners from Yorkshire met with others from across the country to try to stop the project. They say it will blight their homes. Calendar's political correspondent Paul Brand reports