The website promoting the latest British adventure into new railways shows slick pics of trains rushing silently through summer meadows. Its news pages report the latest design contract lettings. Alas, it can find nowhere to accommodate the latest news on the proposed link that would bring Birmingham a few minutes nearer to London. The news is not good. The government has goofed with its sums, and the case for the monstrously expensive new railway is even worse than it was the last time it looked. The line really isn’t worth building.

The worse projections are officially ascribed to a “modelling error”, which translates as the “wishful thinking” which infects all grands projets backed by the state. The rule is to underestimate costs to get a project going, and raise the number only when it’s too politically embarrassing to stop. The MoD have been doing it for decades with their big boys’ toys, and the Olympics provide another version of the game.

The original cost-benefit calculation from the Department for Transport showed that HS2 would be worth £2.40 for every pound it would cost. Nobody believed that – the private sector would be gagging to pay for it on that figure – but as the projected costs rose, that was whittled down to £1.60. By last February, the official figure was £1.40 and now the “modelling error” has brought it down to just £1.20. Given the inevitability of cost over-runs on a £32 billion (that’s £500 for every man, woman and child in the UK) project, a realistic figure would be less than £1 – meaning the line would cost more than it was worth.

The news followed the latest embarrassment over HS1, the high-speed link to the Chunnel. The National Audit Office’s latest analysis exposes the numbers used to justify that line as the sham some of us always suspected they were. The actual number of passengers is just one-third of the level forecast. The rail regulator points out that £32 billion spent on a single new line means £32 billion not spent where it’s really needed elsewhere on the network. The time saved for a total journey promises to be trivial.

Of course our fragrant new Transport Secretary is not deterred by the facts. She urges us to be the new Victorians, and take a 100-year view. Her officials are rapidly rowing away from the idea that cost-benefit analyses are important, while the government is rapidly reaching the most dangerous point in this venture. As with the disastrous Health Bill, it has invested much political capital. Unless it recognises some of the unpleasant facts, it may be incapable of stopping what promises to be the biggest waste of money since Concorde.