An oft expressed contention is that if only we allowed those wise people in Whitehall to plan more of our lives then the future would be made so very much better that we won't mind paying the costs of having those wise people in Whitehall. One problem, among many, with this idea is that it does require the people we're paying for to be wise. Not something that I'm really willing to bet on, that. The Very British Dude makes an excellent point here [3]:

.....the biggest change to transport technology on the horizon, the driverless car. Instead, the Lib-Dems are wibbling about High-Speed Rail which will be almost completely obsolete by 2050 as everyone will be snoozing in their own autonomous vehicles. Such vehicles will run door-to-door on a vastly greater network of tracks (let's call them "roads" shall we?) than any train network will ever be able to compete with.

This is exactly right I think. The planning that we're being offered is that we should have more of a 19th century technology in the 21 st century. And it's entirely ignoring the coming impact of a 21 st century technology.

The arguments in favour of HST and other fast trains etc are capacity and speed. We want or desire a rise in the capacity of people to move around the country simultaneously. And we also want to increase the speed at which they do so because time spent travelling is "dead time". That latter isn't really true what with mobiles and notebooks: and it most certainly won't be true when we're all sitting in the back seats of our Wi Fi enabled cars. Such cars will also solve some to all of the capacity problems: the current road networks can carry a great deal more traffic if it isn't all being directed by that all too fallible few pounds of meat called the human brain.

I will admit to being a little unsure about how quickly computer controlled cars are going to be rolled out. But it wouldn't surprise me at all if they were actually commonplace before anyone even starts breaking ground on HST. Which would be an interesting example of spending £40 billion on a project that was outdated before it was even begun, wouldn't it?