Downing Street insisted the Government was working to get HS2 under control as officials admitted they did not know how much it would cost or when it would be completed.
In a report released on Monday, HS2 Ltd estimated that the cost of building the railway would be between £54 and £66 billion in 2019 prices – between £67 and £83 billion in current prices.
But appearing before the Commons Public Accounts Committee on Thursday, the Department for Transport’s top civil servant said these figures were not “reliable” and an agreed estimate was unlikely to be produced until “well into 2025”.
Both the department and HS2 Ltd have committed to a “reset” of the project in order to control costs and establish a more accurate baseline for assessing performance, while Downing Street said it had already made announcements to get the project under control.
The Prime Minister’s official spokesman said: “The Transport Secretary has asked HS2 to urgently provide updated and clearer estimates of the project as soon as possible, and we’ve made it the number one priority of the new chief executive to drive these costs down.”
He added that the most recent estimates from HS2 Ltd had been made “ahead of the rebaselining work that has been commissioned” and before the Government’s “fresh announcements to get this project under control under new leadership”.
Speaking to the Public Accounts Committee, HS2 Ltd’s new chief executive, Mark Wild, said there were “systemic” and “enduring” problems that had contributed to the project’s spiralling costs, including starting construction too early, not managing risks properly and making incorrect assumptions about productivity.
He suggested work to reset HS2 would be a complex process that would not be complete until 2026.
He said: “You would hope that in the 2030s you would have a functioning railway, but the truth is I do need to do the work.”
Dame Bernadette agreed timelines for running trains between Old Oak Common, in west London, and Birmingham by 2032 were “under pressure” but the “outer limit” of 2036 for running Euston services was still achievable.
Summing up Thursday’s evidence session, Public Accounts Committee chairman Sir Geoffrey Clifton-Brown said: “We don’t know when the reset is going to take place, we don’t know what the cost is going to be, and we don’t know when it is likely to come into operation.”
Meanwhile, Mr Wild declined to apologise for the £100 million bat “shed” built by HS2 in Buckinghamshire, saying it was a legal requirement.
The structure was criticised by the outgoing chair of HS2, Sir Jon Thompson, who said there was “no evidence that high-speed trains interfere with bats”, and has become emblematic in some quarters for the burdens placed on infrastructure projects by planning laws.
Asked if he wanted to apologise for the structure, Mr Wild told MPs that he could “understand why that would raise public concern”, but added: “The law says that we must mitigate damage, harm, to protected species”.
He said: “I can’t apologise for complying with the law. This structure is the most appropriate.
“It is an extraordinary amount of money but it is in the context of a scheme that is costing tens of billions and it’s built for 120 years.”
Dame Bernadette said the Department for Transport and the Treasury had “challenged” the building of the bat tunnel, but found it was “the most efficient remedy” for protecting the species.