It's obviously hard to say exactly, but quite a lot? Remember Phase 2b only releases 4-5ph unless NPR is also built
It's more of a general point that I was making - there are many schemes out there that get ruled out as "too expensive" but are nowhere near as expensive as HS2.
Many suggestions were made about lengthening to 12 coaches, even at 80x capacity, whilst you'd get to about 880, that's still quite a long way short of 1,100 AND the existing trains.
You also don't free to platform space, which even at 2tph releasing one while platform could allow 6 new trains (6 coaches long, so two trains very for in the space of one) in the same platform space for to the shorter turn around times (20 minutes per service rather than 30 minutes).
If it's too lengthen existing services you could across three platforms lengthen 9 services from 4 coaches to 6 coaches (previously 3 services staked in each platform, now two).
The simple answer to this question from my point of view is it shouldn't. For me the cost benefit analysis never stacked up and as the journey time to the north in particular just wasn't going to be a significant enough saving it would not have persuaded me and many others no doubt to switch, and in the process pay the no doubt not insignificant increase in price, if full fat fairs on hs1 services are ending to go by. We simply should have reconfigured services on our existing main lines to get some stops out or other performance improvements in and this could have been done along with many other rail projects for the money that's being spent on effectively a commuter train for Midlands commuters that are no longer commuting because apparently everyone works from home these days, although there is plenty of evidence to the country that I myself have observed
Apologies to all the many on here peddling the climate emergency which again in my view isn't there but you're going to need to save me significantly more than 30 to 45 minutes on a London to Scotland end to end journey time not to mention a lot of money in fares and an increase in onboard facilities before you tempt me away from the plane. Every time I do the train these days it either goes wrong or costs me a fortune because standard class facilities have been paired back so much, particularly on the East coast where four plus hours on an ironing board awaits for the hardy souls doing London to Edinburgh etc
A similar length and distance of journey in a lot of other European countries would see a much more comfortable and spacious standard class interior and a full restaurant service for those wanting it at reasonable prices, but here in the UK we provide less comfort than your average park bench with hundreds of people compressed into metal and plastic smarty tubes with a overpriced and substandard catering service and then we wonder why so many people drive or take the plane
HS2 would allow, through much longer trains, far better seating options than the current trains offer.
Also even if the same ratio of airline to table seats are provided, until the trains reach the same percentage full you've got a better chance of getting a seat at a table (if that's what you want).
Anyway if away comfort is what you want, actually the amount of leg room and elbow room you have on a train is much better (often better than first class on an aircraft, but in standard class on the train).
As to comparing HS1 for ticket prices, a lot of HS1 (domestic) services are small (6 coaches, 122m, 340 seats) with double length trains being something being considered as an upgrade.
HS2 isn't going for that, it's going for most of its services being full length (16 coaches, 400m, 1,100 seats) with half length trains (550 seats, so more than a double length Javelin) being used for off the core services.
A train carrying 240 passengers with a driver cost of £1 per person when changed to a 550 seat train will cost 44p whilst a train with 1,100 seats that per seat cost for the driver fails further still to 22p.
Only that's only half the story, due to the HS2 services being faster than the existing WCML services the amount of driver time falls from 5 hours to do the round trip to Manchester to 3 hours. Whilst the Javelins are faster than the current WCML services, they'll still be slower, let's say out would take them 4 hours, then that 22p would fall to 17p.
That's before you consider the reduced costs of rolling stock (do I need to repeat it, if I do it's below the next paragraph, however I've added in the "Javelin+" option which would be double length trains like is run on HS1).
Whilst HS1 and HS2 share similarities in their names, their operations are going to be very different.
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Existing 9+11+11 coach trains taking 5 hours would require 155 coaches
"Javelin+" with 12 coach trains taking 4 hours would require 144 coaches
"80x+" with 16 coach trains taking 4 hours would require 192 coaches
HS2 services with 16 coach trains taking 3 hours would require 144 coaches
Whilst that's the same as the "javelin+" trains they would have 480 seats compared with 1,100 for the HS2 services.
I'm sure, either those arguing against HS2 never read this, or they don't understand this, or they just ignore it as it do doesn't fit their narrative, but until someone challenges me on the above I'll keep repeating it - sorry for those who get it and get board of reading the same thing.