That is the warning from a group of Members of Parliament (MPs), who form the Public Accounts Committee (PAC), in a new report scrutinizing the project.

An update from ministers at the end of 2024 put the budget of building HS2 from London to Birmingham at between £54 billion and £66 billion in 2019 prices. Adjusted for inflation, that would be between £67 billion and £81.7 billion, against an original budget of £37.5 billion in 2009 prices for the entire line (the northern leg of HS2 running to Manchester was scrapped by former Prime Minister Rishi Sunak in 2023).

The PAC urged the government to lay out to the public what value taxpayers can now expect from the project.

“Thirteen years since HS2 was given the go-ahead by government, it is not known what it will cost, what the final scope will be, when it will be completed, and what benefits it will deliver,� it said.

The Department for Transport and HS2 have promised a “fundamental reset� of the project but the PAC said it wanted to know more details of what is involved.

“The report finds that neither DfT nor HS2 Ltd currently have the skills or capabilities to make a success of the programme,� it said.

The report also specifically highlighted London’s Euston Station, and HS2’s ‘bat tunnel�, as elements of concern.

HS2 is spending £100 million on a shield to protect bats along a 1km-long stretch of ancient woodland in Buckinghamshire. The PAC said the cost of the so-called ‘bat tunnel� did not strike the right balance between protecting wildlife and the burden on the taxpayer.

It noted that the government’s plans to run HS2 through central London to Euston station rest on the £6 billion cost being underpinned by the private sector. But it warned that a clear plan is lacking and expressed scepticism that the private sector would “come forward to the level required�.

Sir Geoffrey Clifton-Brown MP, chair of the PAC, said, “Our Committee has not made recommendations in our report on delivering better outcomes for HS2’s future passengers. We are long past that point. It is time to deal with HS2 as what it is � a cautionary tale that should be studied by future Governments in how not to run a major project. We are sceptical of Government’s ability to successfully deliver even a curtailed scheme, one which we already know will on its face bring very poor value for money. The question has instead become: what possible benefit can the Government now salvage for the taxpayer, from a mess that presents real risks to the UK’s overall reputation?�

A spokesperson for HS2 Ltd said, “Mark Wild, our new chief executive, agrees with the committee’s conclusion that there has been failure in the management of HS2’s cost and schedule. He is taking decisive action to get the project back on track at the lowest feasible cost.

“His fundamental reset is critical to ensure the successful delivery of HS2’s goals � driving economic growth and connecting our biggest cities with fast and reliable journeys.�