You have several demands on the northern ECML which are required, so let's consider them
1) Service from Leeds-Scotland. Leeds is a much much bigger railhead than Doncaster, which already has scottish services and should, in any rejig, get an hourly service. It's much better therefore to route XC scottish services away from Doncaster. Currently Leeds service to Scotland is already crowded and under-run.
Debatable. Doncaster is an important interchange station, with quite a large catchment area (Lincolnshire and Humberside, as well as parts of South Yorkshire). Also, while Doncaster does have Scottish services already, these are very infrequent, with only 8tpd continuing beyond Newcastle, and only 3 services between 9am and 5 pm.
Also re-read my earlier post in this topic. In the current timetable, while there is 2tph from Doncaster to Newcastle, they depart within 10 minutes of each other.
2) Service north of Edinburgh within Scotland. Currently the 3-car 170s up the east coast are very busy, and in the time I've been using them I've yet to see less than a 70% load, even in the very off peak (2pm on a Wednesday afternoon). Not only do the above suggestions cut all long-form trains, they also cut through connections to England from Fife, Angus and Aberdeenshire, for which there is actually a very good market not currently served by the 1tp2h to London.
3) Service from the midlands to the northeast & Scotland. Currently the midlands need to get to Newcastle, so it would seem sensible to route things that way. Given Birmingham already has a connection to Edinburgh via the WCML, lengthening journey times would seem mad, as it would for Manchester (given that sending trains via Leeds creates an increase between 40 minutes and 1 hour).
FYI, the time penalty for XC service going via Leeds and not Doncaster is roughly 20 minutes.
I haven't got that much experience of travelling north of Edinburgh, but from the few services I have used, I can agree with your comments.
I'm not sure about your comment that people from the Midlands need to get to Newcastle though. If the North East XC services are swapped round, so the NESW goes via Doncaster instead, for the Sheffield - Leeds - York passengers, there will be a simple same platform, or at worst, cross platform change at York
So let's think sensibly, and take this from all angles.
1) TransPennine Express
Middlesbrough is going to get wired, this I'm confident of. I'd support additional services to Middlesrough from Manchester, if this wasn't an option, then a fast 158-operated service to Leeds would be. There's no mass market to go to Middlesbrough from the Midlands/South Yorkshire
Is there not? As quite a lot of the members on the forum are not railway staff, we don't get access to a detailed breakdown of what tickets are actually sold. All we can go on is anecdotal evidence and personal experiences, as well as the station usage reports.
2) Cross Country
As above, should serve the most popular destinations. This isn't Middlesbrough. It is Newcastle. Doncaster already has frequent services to Newcastle & Scotland, and will get more. The time saving for Sheffield does exist, but the market for Sheffield-Leeds fasts is a lot bigger, and trades off. 2tph via Leeds terminating at Newcastle seems the best idea. It gives extra Sheffield-Leeds connections (our real moneymaker), and more service on Leeds-Newcastle (our other big flow).
Again, re-read my comments about Doncaster - Edinburgh. I do not call 8tpd between the 2 as frequent, especially when there is on 3 services between 9am and 5pm. Also, taking
all XC services away from Doncaster is a regressive step, as it will half the number of services from there to Newcastle.
3) East Coast
Lots of places in the northeast & Scotland are particularly underserved, especially in terms of through connections, for which the Aberdeen train is inadequate. There's certainly not a market for an hourly service to London given air competition, but there is from Leeds north to Scotland, and from the north of Scotland to Edinburgh & south of it.
Results:
2tph XC Sheffield-Wakefield-Leeds-York-Northallerton-Darlington-Durham-Newcastle
2tph TPE Leeds-Garforth-York-Thirsk-Northallerton-Yarm-Thornaby-Middlesbrough
1tph EC Leeds-York-Darlington-Durham-Newcastle-Scotland
1tph EC London-Doncaster-York-Darlington-Durham-Newcastle-Sunderland
Service results:
Leeds gets an hourly service to Scotland, and quarter-hourly to Newcastle.
Half-hourly Leeds-Sheffield express service.
Scotland gets a regular through service to England.
Aberdeen gets an hourly long-form service to Edinburgh.
Edinburgh gets a half-hourly service to Newcastle.
That plan is simply daft! Let me pick a lot of holes in your plan ....
London - Newcastle - Scotland. That is a big market for East Coast, you according to your plan, it's not needed, so instead you truncate it at Newcastle and reduce the frequency to 1tph
Leeds - Newcastle - Scotland. 4tph Leeds - Newcastle? Is there really that much demand? With the proposed timetable, it goes to 3tph anyway
XC Birmingham - Newcastle. No demand for passengers to go to Doncaster, and the surrounding catchment area?
Newcastle - Scotland. Only 1 (semi) fast tph? Another reduction in frequency ....
Also, is there the demand for a full length train every hour between Aberdeen and Edinburgh?
What about the Inverness and Scarborough services?
Seeing as you haven't mention them, I'm assuming the KX - Leeds services will stay as they are.
Basically, in your "perfect plan", Only Leeds/York - Newcastle - Edinburgh is worth bothering about, sod everyone else that wants to get anywhere using East Coast ....