Plans for a £32 billion rail network with Birmingham at its heart have been slammed by the Commons committee responsible for overseeing public spending.
The Government’s case for building the HS2 line does not stand up to scrutiny, the Public Accounts Committee warned.
And ministers were repeating the mistakes made when building HS1, which runs from London to the Channel Tunnel in Kent, which left taxpayers saddled with £4.8 billion in unexpected debt, MPs said.
They accused the Department for Transport (DfT) of exaggerating the passengers numbers and economic benefits.
The Government assumed time spent travelling was time wasted when, in fact, many people worked during rail journeys, MPs said.
The report will provide ammunition to opponents of high speed rail, who claim the Government’s plans are a waste of money.
Committee chairman Margaret Hodge said: “Some of the assumptions about the benefits of faster travel are untenable.
“The department also told us it had not considered the benefits and costs of alternatives to HS2 such as investment in broadband video-conferencing or investment in alternative, more local train routes.
“The department must revisit its assumptions on HS2 and develop a full understanding of the benefits and costs of high-speed travel compared to the alternatives.”
Most of Birmingham’s business leaders, councillors and MPs are behind plans to build a high speed rail network from London to Birmingham and on Leeds and Newcastle.
The line, which is backed by all three major parties at Westminster, is due to open in 2026 and supporters say it will bring an estimated 8,000 jobs to Birmingham. It will include a major new rail station at Curzon Street, in the city centre.
But it has aroused strong opposition elsewhere. A number of MPs in Staffordshire and Warwickshire oppose the plan, as does Coventry City Council.
A DfT spokesman said: “Network Rail predicts the West Coast Main Line will be full by the mid-2020s and HS2 presents the most effective solution to this looming capacity crunch facing our rail network.
“This is in addition to the jobs, regional regeneration and improved connectivity the project will deliver.”