I think that if HS2 was sold as a capacity/reliability upgrade rather than a speed upgrade objections would have been far less.
I'm not sure. There's a lot of people living in the area affected who are objecting becasue of that, and will take on any objection. There are also some people looking at the vast cost and thinking it's a waste.
We've got into a bit of a rut on infrastructure. The Major government gave up on all new large road projects becasue of a combination of trying to balance the books and stop Swampy and his mates from being on telly every night. New Labour didn't really reverse that. And no-one seems to mention new roads any more. I don't think we can usefully expand the East Coast and West Coast rail lines. And we don't even have much more air capacity around London and the South East.
Also NIMBYs seem to be becoming BANANAs (Build Absolutely Nothing Anywhere Near Anything)...
And yet we're apparently going to have 75 million pepole living in this rather crowded country by 2030. So unless we can get most of those to live up North, we're in danger of tipping the South East into the sea (we're supposedly getting fatter as well remember). Don't laugh up in Scotland, we may all drown, but you'll start sliding as the country tips up, and then you'll end up being English...
Did the HS2 business case take this into account? Did it compare the environmental cost of all those people flying? The NIMBYs managed to kill the Chunnel frieght link that was going to go up via Chiltern Railways and some of the old Midlands track. Which was a shame.
I don't know if a business case is going to give any better idea of what's going on than a politician's guess. The answer that comes out is going to be just as reliant on what assumptions our economist chooses and what costs/benefits are ignored or impossible to measure.
I suspect the correct answer would be to build a new North-South motorway. Can't see that going down too well though. So I supect one of the politicians' calculations was that surely environmentalists won't object to trains, which just leaves the locals whose house-prices might fall.
So I'd say the real answer is it's all guesswork. And economists sometimes delude themselves that they're dealing with a science. But it can't be because it's impossible to have a spare economy to test theories on, and because politics and voter-perception are just as important as cold hard cash.
Also how the hell can we even know the outcome of current policy and trends over the next 30 years. Let alone whatever circumstances are going to hold in 50-100?
Although on the other hand, it's still a good thing to try to do the economics right. I just don't believe it's any more a reliable guide to the future than anything else we have.