ValleyLines electrification by 2020 would release 30 Pacers directly, I don't see how cascaded 165s and 166s from GW electrification could provide 30 DMUs that are suitable for the Valleys to release those Pacers if the Valleys aren't electrified. Depending on how much of the Valleys network is electrified (I think that's the question now, not will it be done at all), ATW might be able to shed 8 150s to release GW's Pacer allocation of 8 units. Some of the 165s/166s released could work some of the lines east of Newcastle/Darlington, and if cleared some could provide additional capacity on local services around Bristol or Exeter (depending on how much around Bristol is electrified).
With reference to Nym's plan, I agree with this view. I can never see 165s or 166s being cleared to operate the branch lines in Devon and Cornwall, so it is unlikely or impossible that a cascade of 165s to the West Country, operating regional services, out of Bristol, will release a proportional number of 150s for use by ATW as FGW will still have a need for 150s on the branches.
Displaced 165s are, however, more likely to lead to the withdrawal FGWs' eight class 143 Pacers by releasing a few 150s within FGW than through ATW releasing 150s.
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I've done a more detailed analysis of my take on Nym's proposals. Admittedly I do tend to err on the side of caution when it comes to calculating the number of units released by electrification projects. However, in assessing these figures I have taken a more aggressive line than in my own electrification driven Pacer replacement scheme, although I still come up with a number of units replaced less than that necessary to replace all the 142s. Which still of course leaves the, admittedly better quality, 143s and 144s to worry about.
I'm working from:
GW Electrification
Lancs & Liverpool Triangle
TPE North to York and Hull (Not Middlesbrough) with associated tiny additional bits.
GW Electrification by internal cascade can clear all pacers outside of the North of England by cascade of turbos with "No Growth", growth can be catered for by adding in the Thames Valley Branch Lines.
There's still going to be a requirement for a small number of Network Turbos to operate the Thames Valley branches, as you correctly state: It has been previously calculated on this forum that this could equate to eleven or twelve diagrams; allowing for some services being formed of pairs of units, for the sake of argument I have left the 21 x 3-car class 166s allocated to Thames Valley services.
This leaves 36 class 165s to cascade to Bristol area regional services, 16 x 3-car units and 20 x 2-car units. As a nice tidy piece of maths I have assumed that this would be sufficient to allow FGW to lose its' 20 x class 150/2 units to ATW, while FGW retain the 18 x class 150/1s that they currently operate in order to operate the various branch lines where 165s are unlikely to be cleared: Bearing in mind here that particularly during the summer months a number of trains on the Devon and Cornish branches are formed of pairs of units.
20 x class 150s is certainly enough to rid ATW of it's 15 x class 142s, but not enough to rid it of its' entire 30 strong Pacer fleet. I will conservatively assume then that ATW will retain its' 15 x class 143 Pacers, as the additional 5 x 150s over that required to replace ATWs' 142s could surely be used for strengthening, although I have also provided that ATW could gain FGWs' two remaining 2-car 158s so that they don't have to resort to using 150s on long distance regional work.
Lancs & Liverpool clears a fair few Diesel diagrams when properly completed (from Northern, TPE have already internally cascaded theirs, my last count was 24 diagrams)
Hazel Grove - Preston: 4 Dia.
Victoria - Blackpool: 3 Dia.
Liverpool - Wigan: 4 Dia.
Liverpool - Blackpool: 4 Dia.
Airport - Liverpool (Path to TPE): 3 Dia.
Victoria - Liverpool: 3 Dia.
Liverpool - Warrington BQ: 3 Dia.
Then some clever timetabling and alternate service provision also clears...
2 Dia from Wigan - Victoria via Bolton (Split the route at Bolton, via Westhaughton is suitable for 'Exempt' Pacers for additonal savings on sprinters)
Southport - Airport is planned to move to via Atherton, units can be saved from this route by provision of better services via Eccles.
All in all, you're looking at (including maintenance capacity) about 30 - 35 units.
I concur absolutely with your figures for the number of diagrams replaced by North West electrification. However, as an aside it is worth noting that Newton Heath maintain and operate 44 class 142 Pacers, so the numbers you have stated fall well short of the numbers needed to replace all of Newton Heaths' Pacers, and it has also been said that the North West electrification will not see any units withdrawn: They will be used for strengthening elsewhere.
TPE North has two aspects to it, the TPE fleet re-assignment and Northern direct unit saves.
Direct Saves for Northern come in at (With sensible infill, some routes are split)
Leeds - York: (Nothing directly, as these all run from other places, and will proberbly continue to, such as York - Blackpool running onto Scarborough and a Calder Valley service running onto Middlesbrough)
York - Hull: 2 dia.
Selby - Leeds: 2 dia.
Leeds - Huddersfeild via Dewsbury: 2 dia.
Victoria - Huddersfeild: 2 dia.
So thats 10 units directly replaced.
Isn't that eight units? Or did I miss something? So that's two Newton Heath 142 or 150 diagrams, we'll say for the sake of argument that it's two 142s replaced, and about half of the Heaton 142 diagrams that operate in Yorkshire, assuming that as York to Hull is principally 158 operated these two units will be able to find a home replacing other units on other Northern services.
TPE has it's fleet of 51 + 9, with these needing to stay...
Cleethorpes - Manchester Airport (Divert to Liverpool Lime Street via CLC) 10 dia.
Chances are we will still have some direct Barrow services, but lets assume not for now, makes the numbers look better if we say it's a Turbostar running from Preston, esp. with the Scottish services going hourly, also assuming Electrification of the Windermere Branch.
The following services would then go to 185 operation (line quality improvments permitting, also trying to keep things close to existing depots.)
Scarbrough - York 1tph 1 dia.
Blackpool North - Scarbrough 1tph 9 dia.
Manchester Airport - Manchester Victoria - Calder Valley - Bradford - Leeds - York - ?Middlesbrough 1tph 8dia.
Chester - Manchester Victoria - Calder Valley - Bradford - Leeds 1tph 5 dia.
Buxton - Manchester Piccadilly 1/2tph OP/Pk journey times under an hour, express via Hazel Grove (Picc - Stockport - Hazel Grove - Stations to Buxton) 4 units.
Sheffeild or Doncaster - Manchester Airport via Hope Valley and Victoria 7/8 Dia. (Possibly the all stations service)
That leaves 6 maintenance spares, and has replaces about 40 of Northern's diagrams, some of these doubled up so one can assume about 50 units.
The problem with some of these routes, Blackpool North to Scarborough particularly, although only from York at present, is that they are presently 158 operated, and you can't just keep cascading 158s further down the chain to replace more commuter or rural specified stock on less and less suitable work. As for the proposed York to Scarborough shuttle, this is already operated by a 185 as part of a longer distance service, so releases nothing. Finally, irrelevant of what sort of frequency you might be proposing for a Hope Valley all stations service, in reality the present Hope Valley all stations Northern service only equates to a total of three or perhaps four all-day diagrams.
Valley Lines electrification is urgently needed then as one of the most effective ways of replacing Pacers: That would be 30 units gone, and FGWs' eight 143s finished off by GW electrification, in one go.
