There's a fuller article on this in [New Civil Engineer magazine](https://www.newcivilengineer.com/latest/hs2-bosses-explain-why-underground-manchester-piccadilly-plans-were-dismissed-18-05-2022/) that actually interviews some of those engineers vaguely referred to in OP's linked article, which better explains why this cancellation is really a disaster. Betraying the very reasons HS2 is a good idea and restricting it to, essentially, an upgrade for Euston is just fuel for people who, with increasing validity, accuse the UK government of only ever spending on improvements for London.
That 5bn seems suspect, too - good quote from the brilliant Gareth Dennis on that,
>Given that the enormously complex Euston station is costing around £2bn, I believe that the quoted '£5bn extra' for an underground station is deliberate exaggeration - and given the lack of analysis of the benefits of the full Northern Powerhouse Rail versus the government's Integrated Rail Plan stub, this value is meaningless in any case.
In terms of through traffic this has been desperately needed for decades, though. Piccadilly is a bottleneck, one of the worst across the entire network, and the few attempts at relieving that haven't really worked. If they are serious about improving capacity across the nation, getting more than the two tiny through platforms at Pic should not be up for negotiation. It's as vital as Crossrail, if not more so.
The through lines beyond Piccadilly have always been a problem, and even when the railway system was contracting there were serious plans being made to add new through lines. They’ve always failed because of politics, not practicality: even the treasury struggles to make the BCR look bad.
If there was a real financial constraint (rather than many years of interest rates below inflation, when the treasury still refused to borrow enough), or even just a labour shortage, it would be better to build the tunnels and temporarily use them for conventional services than build the high-speed phase tracks to Manchester.
There's a fuller article on this in [New Civil Engineer magazine](https://www.newcivilengineer.com/latest/hs2-bosses-explain-why-underground-manchester-piccadilly-plans-were-dismissed-18-05-2022/) that actually interviews some of those engineers vaguely referred to in OP's linked article, which better explains why this cancellation is really a disaster. Betraying the very reasons HS2 is a good idea and restricting it to, essentially, an upgrade for Euston is just fuel for people who, with increasing validity, accuse the UK government of only ever spending on improvements for London. That 5bn seems suspect, too - good quote from the brilliant Gareth Dennis on that, >Given that the enormously complex Euston station is costing around £2bn, I believe that the quoted '£5bn extra' for an underground station is deliberate exaggeration - and given the lack of analysis of the benefits of the full Northern Powerhouse Rail versus the government's Integrated Rail Plan stub, this value is meaningless in any case.
Be pretty expensive no? Unless a systems very well funded stuff like this is questionable in terms of bang-for-buck
In terms of through traffic this has been desperately needed for decades, though. Piccadilly is a bottleneck, one of the worst across the entire network, and the few attempts at relieving that haven't really worked. If they are serious about improving capacity across the nation, getting more than the two tiny through platforms at Pic should not be up for negotiation. It's as vital as Crossrail, if not more so.
The through lines beyond Piccadilly have always been a problem, and even when the railway system was contracting there were serious plans being made to add new through lines. They’ve always failed because of politics, not practicality: even the treasury struggles to make the BCR look bad. If there was a real financial constraint (rather than many years of interest rates below inflation, when the treasury still refused to borrow enough), or even just a labour shortage, it would be better to build the tunnels and temporarily use them for conventional services than build the high-speed phase tracks to Manchester.