After 12 years in the planning, the north’s flagship rail scheme still has no detailed design and a £45 billion budget that the public accounts committee says was set before anyone knew what it would build.

The plan to transform train services across the north of England is at risk of sliding into the same fiasco that has engulfed HS2, according to parliament’s spending watchdog, which says the scheme still lacks a proper design and a realistic budget after more than a decade of planning.

In a withering report, the Commons public accounts committee (PAC) said Northern Powerhouse Rail had no detailed design to speak of after 12 years on the drawing board, and warned that its £45 billion budget had become “decoupled from reality”. As it stands, the committee said, the project is likely to fail to deliver the improvements promised and risks becoming yet another government infrastructure albatross.

Originally conceived as a high-speed line linking Liverpool, Manchester and Leeds, the scheme has since been pared back to a series of local upgrades intended to deliver faster and more frequent services. The government revived the programme in January with a phased £45 billion vision for the north, but the PAC is unconvinced the numbers stack up.

The committee said it was “not confident that the Department for Transport (DfT) has learnt all the lessons from its past failures in its management of other rail projects”, pointing above all to the truncated HS2 north-south link. HS2 has busted its budget and could cost well in excess of £100 billion despite now running only as far as Birmingham, and is expected to be at least five years late.

On the money, the PAC was blunt. There was “no convincing plan” to deliver Northern Powerhouse Rail’s aims within the £45 billion cap, it said, and no explanation of how the Treasury had arrived at the figure in the first place, with no formal design, scope or costing yet published.

Clive Betts, the PAC’s deputy chair, said there was no doubt that railways in the north needed transforming to deliver jobs, mobility and productivity. But having taken evidence from interested parties, he warned: “Our committee has heard troubling echoes of the same mistakes in loose governance that HS2 made early on.

“Much of the project remains almost impressionistic. Both the Treasury and DfT have questions to answer about the project’s £45 billion funding cap. We need to know how this figure was arrived at and how DfT will keep to it. Capping a project’s funding before it was even designed or costed feels like putting a roof on a house before the foundations are laid.”

Betts reserved particular scorn for the decision to let HS2 Ltd, the agency set up to deliver HS2, advise on Northern Powerhouse Rail, calling it laughable that a body with such a record of failure should be shaping the north’s next big scheme.

The report lands as northern leaders press for a firmer commitment to the region. Greater Manchester mayor Andy Burnham, a vocal champion of devolution who has warned the north faces “Armageddon” without proper rail links, has continued to push for better transport connections and a shift of power away from Westminster.

The committee wants clarity, and quickly. It called on the DfT, already stretched by HS2 and the creation of Great British Railways, the new publicly controlled operator, to front up: “Within six months, the department should write to us to confirm whether Northern Powerhouse Rail is a mega-project or not.”

That question matters because the answer determines how the scheme is governed, scrutinised and funded, and the committee’s frustration is that, 12 years in, it still cannot be answered. Ministers have also faced pressure over cheaper alternatives elsewhere on the network, including a cut-price “HS2-light” line beyond Birmingham being weighed up by officials.

The Department for Transport pushed back firmly. “Northern Powerhouse Rail will deliver the biggest investment in rail connectivity in a generation, giving the north the transport links it deserves and driving growth, jobs and investment across the region,” a spokesperson said.

“NPR will not repeat the mistakes of HS2, which is why we accepted all the recommendations of the James Stewart review and are taking a disciplined, phased approach, completing detailed technical work with all stakeholders before fixing precise choices for major infrastructure.

“Since announcing NPR in January, we have worked closely with mayors to take the project forward. New joint partnership forums are already overseeing the next stage of development and Network Rail has begun developing engineering designs.”

The full findings are set out in the PAC’s report on Northern Powerhouse Rail, which draws on National Audit Office analysis showing the DfT will have spent some £410 million on the programme by March 2026. For a scheme meant to rebalance the economy, the watchdog’s message is uncomfortable: design first, cost second, and cap the budget only once you know what you are building, rather than the other way round.