@HSTEd thanks for the detail reply, which deserves a detailed response.
I think you will find that London-Leeds distances are generally comparable via Birmingham and Manchester and via Birmingham and Nottingham.
The dog leg is already committed by going to Birmingham International in the first place.
30 minutes slower from where to where, using what assumptions?
Leeds to Birmingham and Leeds to London:
Current time Via Manc (your numbers) Via HS2E (journey times stated by HS2)
to Brum 2hrs 80m (IRP numbers) 49m
to Lndn 2h10-2h15 108m (your numbers) 81m
Even if all you do is build Marsden to Leeds as a HSL, journey times for London-York are not absurd
Slower than the fastest trains but not ridiculously so.
If you build some high speed line between York and Leeds using some of the vast amounts of money you save from the reduced length of the F system (taking NPR as read) you will beat the classic times, at which point the traffic will transfer.
70 ish minutes London-Manchester, IRP 33 minutes Manchester Leeds, 5 minute dwell in Manchester - 108 minutes.
Even classic journey time from Leeds-York is 23 minutes or so with another few minutes to dwell in Leeds.
So probably looking at something like 135 minutes - 2hr15.
25 minutes slower than the fastest, but not that much slower than many of the trains today, which are often longer than 2hr5.
With the track saved from not building the Nottingham-Leeds section of HS2, plus the York branch, you can build a high speed line from Marsden to Leeds and from Leeds to York - with some left over.
At which point you will match the fastest classic trains to York easily, and the traffic will transfer.
You probably save approaching 15 minutes for Marsden-Leeds alone.
You wouldn't be able to save 15 minutes for Marsden-Leeds. That would give a Manchester-Leeds journey of 18 minutes. 25 minutes is probably the best you could hope for, and that would be a very fast alignment. Leeds-York is a relative short distance so you won't have time to get to high speeds. But you could perhaps get the time down to 15 minutes.
Even with the high speed sections in place as you propose, based on your timings you would not see a London-York via Manchester journey time less than 2 hours (70m Lon-Manc, 5m dwell, 25m NPR Manc to Lds, 5m dwell, 15m Lds-York, being generous with the NPR and).
Uh..... the F network Birmingham-York journey time via Manchester will still absolutely crush the classic one.
The 2019 XC timetable had York-Birmingham timed at 1h52. Via Manchester on current NPR plans it would be about 1h45. With your proposed additional high speed sections that may come down to 90 minutes. So fair enough, you could save 20 minutes on the current journey. Certainly an improvement on existing, but not crushing it compared to HS2E which would have dropped the journey to under 1 hour.
Sorry - 30km.
But compared to getting on for four times that from Leeds to Nottingham, plus the York branch.
It isn't going to be more expensive.
Weren't you going to build a York branch?
To match the design capacity of HS2E the NPR line would have to cater for 400m long trains and UIC 'GC' structural loading gauge. Big tunnels. Tunnelling is an order of magnitude more expensive than surface rail. And a major rebuild at Leeds. And York as well if you don't want additional 400m length terminating platforms at Leeds.
The ever extending reach of metro-isation.
Railways trend towards being increasingly metro-ised, and the current structure of HS2 does not follow this trend.
It's design for relatively low intensity high speed services between small numbers of stations.
Low intensity? HS2 will be the most intensely used high speed line in the world. Have you considered how many trains per hour HS2 was going to get on each branch? Then add on the additional services Midlands connect and NPR were hoping to add to it.
HS2 is all about metro-isation - getting rid of the jack-of-all-trades railway and giving similar speed trains their own tracks, allowing a massive increase in frequency, both on HS2, and the classic network.
@quantinghome - what was Operation Princess, out of interest?
Hi Jimbo, welcome to the forum.
Operation Princess was the grandiose title given by Virgin Cross Country to its new service launched in 2002. New trains, new clockface timetable with double the train frequency, reduced journey times.
It was so-named because the Cross Country route was called the 'Cinderella' service of BR's intercity network.
It was a complete disaster. The timetable didn't work. The new trains were very short and inefficiently laid out so didn't have nearly enough capacity. A more robust timetable was sorted out by the end of 2003, but with longer journey times, there weren't enough trains to run the network, which had to be cut back to the core routes we have today. Arguably the cross country network has never really recovered.