Bad news: the economic turkey that is HS2 has just become more expensive. Forget £32.8bn, the working assumption until Wednesday for the cost of building the high-speed railway. The new price tag is £42.6bn, the transport secretary, Patrick McLoughlin, told the Commons.
Yes, the new number includes "contingencies", but so did the old number. Most of the extra costs derive from route changes, extra tunnels and the need to link HS2 to HS1, the line to the channel tunnel.
That's the way of things with big infrastructure projects, of course. The cost usually goes up. It happened with the west coast mainline and the Olympics.
By now, though, the government and the Labour party should be asking the hard question: since no project can be allowed a limitless budget, at what point would they deem HS2 to be too expensive?
They should start by studying last month's excellent report by the National Audit Office, which pointed out two uncomfortable truths.
First, the economic benefits from HS2 have fallen radically during the planning process. Back in 2010, it was envisaged that every £1 spent on the first stage of the line between London and Birmingham would yield £2.60 of benefits. Since then the figure has fallen to £1.40 – and that was using the old projected costs.
Second, heroic assumptions have been made in calculating the supposed economic benefits. For example, the colossal sum of £12.6bn is meant to arise from carrying business travellers at faster speeds. But the Department for Transport appears to have assumed that business folk do no work on trains, which is clearly nonsense in the age of Wi-Fi.
As the NAO put it, the department's methodology "uses a simplifying assumption that time spent travelling is unproductive".
The government should go back to the drawing board. There may be an urgent need to increase rail capacity but HS2 is highly unlikely to be the most sensible solution. The economic case, already marginal, gets worse with every new set of numbers. It is time to consider smaller projects with quicker and more certain benefits.
