On Thursday Britain’s Twitter population woke up to exciting news from the Department for Transport (DfT): apparently “New technology used in bi-mode trains will improve rail journeys for passengers in Wales, the Midlands and the North.”

Great. To what do the people of Wales, the Midlands and the North owe this bounteous windfall? We did not have far to look. It turned out that, a bit like your spouse who greets you with unusual affection and serves you your favourite meal before sheepishly mumbling that they’ve written off your brand new car, the public was being softened up for bad news.

Specifically, the news that plans by Network Rail to electrify about 245km of rail routes in, er, Wales, the Midlands and the North, had all been cancelled. As a result, Nottingham, Derby, Sheffield, Windermere, and Swansea will continue to be served by diesel and not electric trains for the foreseeable future, though they’ll also get bi-mode trains (that is, trains with both diesel and electric traction).

Now, there are many ways to critique this decision. You could argue that electric trains are more reliable and tend to be quicker. You could point out that money already spent on the projects has been wasted, and rail contractors may have to shed jobs. You could also say that electrifying lines around major conurbations like Sheffield and Swansea could have opened up possibilities for more frequent, efficient suburban rail services.

However, your humble writer prefers to critique the decision according to how it meets the stated aims of the man who took it, transport secretary Chris Grayling. On the same day that Grayling announced the cancellations, he also issued new guidance to the rail regulator, the Office of Rail & Road, saying that “improving efficiency is vital if we are to maximise the value of taxpayer spending on the railway”.

Fair enough. So how does cancelling the electrification of the South Wales Main Line, most of the Midland Main Line and the Windermere branch line improve efficiency on the railway?

That’s easy. It doesn’t.

Electric trains are cheaper to run than diesel ones, because they’re simpler and cleaner. They are also lighter, which means they reduce wear and tear on the track, in turn lowering infrastructure maintenance costs. Electrification thus reduces the operational cost of the railway, and in time should pay for itself on the two big projects here (the Windermere line makes sense as part of a wider electrified network around Manchester).

So what justification is there for the scrapping of projects that would have lowered the overall cost of the railway in the long term just for a bit of short-term savings? Perhaps these cool new ‘bi-mode’ trains will save money? Well, no. Bi-mode trains are basically electric trains with diesel engines slung underneath, which means more weight, less fuel efficiency and more running costs compared to electric.

In fact, the DfT’s favourite bi-mode, the Hitachi trains which will run on the Great Western Main Line to Swansea, are probably the most expensive trains ever ordered. A calculation made by Modern Railways magazine’s Roger Ford in 2012, when the trains had just been financed, found that they would cost twice as much per carriage in service as a Virgin Trains Pendolino at £74,000 a month.

Actually, that figure includes some cheaper electric-only trains: the figure for bi-modes will be higher. And now that the DfT has gone cold on electrification, it’s told Hitachi to convert more of those electric-only trains to bi-mode, further ramping up the expense.

Nor is it really credible to simply blame National Rail (NR). Sure, it has gone spectacularly over budget on the Great Western electrification, but most of that is not money actually wasted: it’s that the original budget of about £874m was unrealistically low, because the project wasn’t scoped and assessed for long enough before construction began.

NR’s worst failing might’ve been not standing up to the DfT, who – possibly under pressure from George Osborne’s Treasury, keen to use infrastructure spending as a political tool – pushed them into approving the project at a much earlier stage than they would normally allow, as NR’s chief executive has admitted .

Warm congratulations, then, to Chris Grayling for demanding the railway become more efficient and reducing its efficiency on the same day.

René Lavanchy is a recovering infrastructure finance journalist and tweets at @InfraPunk.