Comparing the WCML, often said to be the busiest mixed-use railway in Europe, with the predominantly commuter lines out of Waterloo and Victoria and the relatively under-utilised GWML is really comparing apples and oranges.
Comparing the WCML might with services out of Waterloo and Victoria might be like comparing apples and oranges, but the fact is apples and oranges are both edible fruits and both the commuter lines into the south-London termini and the WCML are very busy. As different as the services out of Euston are from the services out of Victoria/Waterloo, both routes are going to need a major step change in capacity if rail passenger growth continues, Waterloo and Victoria even more so than Euston I would guess. If there's a case for providing a huge amount of extra capacity for the WCML coridor by building a new line surely there's also a case for a new line (perhaps not a true HSR one, due to my other point about 250mph being too fast to be 'green' unless there is aviation to compete with. but one in the 125mph-155mph range). The WCML isn't really full quite yet, not all the Pendos have been extended to 11-car after all, whereas I think more services into Waterloo are nearer maximum length.
As for the GWML being 'relatively under-utilised', aren't most of the top-10 crowded services FirstGW operated (or are they the 166/165-worked Thames Valley services and the 2+8 IC125s on the longer-distance trains have enough space)? Even if the line is not full now, continued growth will require a new paralell line to provide extra capacity. Even if there's no passenger growth, it'd be great if we had the rail capacity to suddenly cause a huge modal shift of freight from lorry to rail.
The Great Western still has potential for better utilisation of/extra capacity through electrification, IEP and ERTMS
Electrification may help capacity, but IEP is a step in the other direction. Ok, there are proposals to increase Bristol services to 4tph, but with the IEP fleet makeup published in Modern Railways either some of those or the Cardiff and Swansea services will be formed of 5-car IEP sets, rather than the present 2+8 IC125 fleet.
As for extending HS2 to Heathrow, it already tunnels east into Euston - the cost of then tunnelling back towards Old Oak Common and onto Heathrow would cost a vast and completely unjustifiable amount. Changing at OOC for Heathrow Express would cost a fraction of such a scheme and would probably be quicker too.
If the object was to extend HS2 to Heathrow I would agree, however the point of my suggestion tunnelling back under London towards Heathrow was as the starting point for new lines to Reading and Southampton/Portsmouth to provide a capacity boost on these routes. It also has the added benifit of a potential smaller footprint at Euston, by making it a through station less platforms should be needed, and splitting the service out again to the south and west means there is no need to find space for a terminous capable of terminating the entire HS2 service since there'd be nowhere that every service terminates.
I heard an anti HS2 guy on Radio 4 say that because any slots at Heathrow will be filled by aircraft going elsewhere then the green argument that HS2 will be greener because it replaces some domestic flights doesn't hold water.
Maybe that'll happen, maybe it won't. In my opinion, we should ban any form of airport expansion, knock out domestic and near-European flights with HighSpeed Rail, then close some airports and move the remaining (long-haul) flights from them into the released capacity at larger airports like Heathrow. Alternatively, instead of closing airports you could just cap flights at current levels and perhaps gain improved punctuallity by having airports running at far less than their full capacity so things don't get congested.
if you're going to run high speed trains but not stop them at Birmingham you're probably missing out on one of the biggest sources of paying passengers and not making use of extra capacity over the part of the route where it's needed most. Adding two slower lines to add capacity for that part of the route adds substantial cost and is just perverse.
I've attached a rough diagram of my proposal, and what I think the government's is. Note that, unless I'm wrong, the government's proposal does just that, routing HighSpeed services to Manchester/Leeds/Liverpool/Glasgow via Birmingham International only, not central Birmingham. The central Birmingham HS2 station, as far as I can tell, would be served only be served only by London/Europe - Birmingham services and Birmingham - Leeds services (just like the present WCML suituation, most Manchester and Scotland services from London avoid Birmingham), unless my proposal of making central Birmingham a through station was carried out (in which case, Birmingham would have all HS trains to Manchester etc. calling and no HS services just to London that didn't come from further north). If Birmingham central absolutely HAS to be a dead-end spur as the current plans seem to be, that is when I'd suggest London - Birmingham services being 125mph and the 4-track suggestion south of Birmingham International was to ensure these don't hold up the HS trains to Manchester, Liverpool etc. (if you can path a mix of 125mph Birmingham services and 200mph Manchester services on a 2-track HS2 then great, keep it 2-track).
The destonations north/south are only illustrative, it's more to give the general idea than a hard and fast proposal, and the number of lines is no indication of frequency (eg. the Eurostar line(s) would be one an hour max, more likely only a handful of trains a day, but other routes much more frequent).
Welsh politicians have begun debating what to do with the £2bn they would recieve under the Barnett formula as a consequence of HS2. Main idea being put forward is to electrify the North Wales lines and provide good connections to HS2 at Crewe.
If using the HS2 Barnett consequentual is the only way to get north Wales wires then fair enough. If north Wales electrification doesn't have to be funded that way though, I wonder if that £2bn Barnett consequential would cover a Welsh equivelent of the 'north-south' HighSpeed Y-Network in England? Instead of new 250mph lines, the Welsh equivelent I propose would consist of:
- 90mph Bangor - Caernarfon - Porthmadog line (taking a short-cut rather than going via Afon-Wen as it would if it was a straight reopening), capable of at least 1.5tph between Bangor and Caernarfon and 0.5tph between Caernarfon and Porthmadog
- Upgraded Cambrian Coast Line between Porthmadog and Dovey Junction, to take an hourly service (0.5tph from Pwllheli, 0.5tph from Bangor) with reduced journey times at least for one train every two hours
- Upgraded Cambrian Main Line between Dovey Junction and Welshpool to take 1.5tph minimum
- Reopened Welshpool - Oswestry - Gobowen route, taking at least 0.5tph
- Broadly 90mph spine Moat Lane Junction - Builth Road - Brecon - Merthyr on a mixture of new and reopened routes capable of an hourly service and possibly electrified between Merthyr and Brecon
Unlike England's, the Welsh north-south divide is physical (at least as far as rail is concerned) rather than purely ecconomic/social, the above would heal at least the physical aspect and hopefully generate significant modal shift to public transport from private cars. If it wouldn't cover the whole cost, how much of the above would the £2bn buy?