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 拢54 billion and 拢66 billion in 2019 prices. Adjusted for inflation, that would be between 拢67 billion and 拢81.7 billion, against an original budget of 拢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.

鈥淭hirteen 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,鈥� it said.

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

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

The report also specifically highlighted London鈥檚 Euston Station, and HS2鈥檚 鈥榖at tunnel鈥�, as elements of concern.

HS2 is spending 拢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 鈥榖at tunnel鈥� did not strike the right balance between protecting wildlife and the burden on the taxpayer.

It noted that the government鈥檚 plans to run HS2 through central London to Euston station rest on the 拢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 鈥渃ome forward to the level required鈥�.

Sir Geoffrey Clifton-Brown MP, chair of the PAC, said, 鈥淥ur Committee has not made recommendations in our report on delivering better outcomes for HS2鈥檚 future passengers. We are long past that point. It is time to deal with HS2 as what it is 鈥� a cautionary tale that should be studied by future Governments in how not to run a major project. We are sceptical of Government鈥檚 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鈥檚 overall reputation?鈥�

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

鈥淗is fundamental reset is critical to ensure the successful delivery of HS2鈥檚 goals 鈥� driving economic growth and connecting our biggest cities with fast and reliable journeys.鈥�