To answer the original topic... I don't know. It's certainly a good and timely idea for a thread, but Im not sure about an answer.
At the moment we are all complaining about thing being gold plated, but then people like to complain about other projects being built on a shoestring (since enthusiasts like to pigeon hole things in those two extremes).
For example, according to some posters on here, the Borders Line should have been fully double tracked, the Ebbw Vale branch should have been built straight through to central Ebbw Vale from day one, every new line should have been electrified, all 800/801s should be built ten coaches long, everything should be fully specced at the start (however expensive that would make it, even if it would ruin the business case).
So, whilst I appreciate the problems of increasing costs, I can at least understand why someone decided to try to "future-proof" the GWML. If we accept that lines only get properly upgraded every thirty/ fifty years then maybe it's understandable to try to build a GWML fit for the 2050s (even if there's no 140mph running etc required any time soon).
I'm not sure that there is any financial argument for electrifying the three Thames Valley branches. They are not very long, speeds are low and the trains are short.
And what, exactly, is the problem with 'diesel islands'? We are not talking Modernisation Plan diesels here. There are three short, effectively self-contained, branches in the Thames Valley. At 45/50mph maximum speed the trains won't wear out quickly so check the brake pads once a month and send a fuel bowser round to each of them once a week. Oh, and somebody to sweep up and clean the windows every night.
Don't over-complicate things.
Sounds like a job for D-stock in that case (if the token daily services to Paddington are withdrawn, as poor use of scarce GWML paths that could easily be filled by a two hundred metre Reading service?
Short, self contained branchlines, low top speed, no need to get up to main line speed, minimal maintenance
What the débâcle has really shown is that (a) the requirements specification has to be fixed before one starts and (b) it should not be changed once work has started. This requires a project manager who can say NO.
But all this is well known in those companies that make things...
...I suppose civil servants don't make things.
True the best point on the thread thus far.
One of the biggest weaknesses with the 800s is that they have become camels due to the changing specification requirements. Theres a lot of good in there, but a lot of compromise too. If we had come up with a great specification in the first place we could have had good trains in service already (rather than paying more for great trains that arent running yet, because designers have had to find room for lots of metaphorical bells and whistles).
Same goes for the electrification specifications, the decision on Crossrail coming to Reading, clearances, methods of getting the kit up etc.
But I dont know how youd get a major political project (that cant neatly be completed within one parliament) funded/ designed/ built without elements of it being watered down, scope changing, different safety requirements etc.
Are there any railway men (to use that beloved phrase) capable of standing up to more than one Government, keeping a lid on costs, refusing to extend the scope beyond the initial brief etc?
Im really not sure what the answer is here. Railways are so politicised that you couldnt run such a big project without elected representatives sticking their noses in, trimming budgets, trying to extend the scope, throwing in other requirements, worrying about political pressure from angry groups like the Goring Gap folks.
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As for the idea of avoiding Reading... I'm far from convinced.
There seems to be an obsession of some enthusiasts to try to build lines/ run services that avoid the biggest intermediate places. Carmarthen to Cardiff without actually serving central Swansea. Ayrshire to Edinburgh without actually serving central Glasgow.
I don't think that there's enough freight from Southampton/ south coast to the Midlands/ beyond to warrant a separate line.
I don't think that there'd be enough passengers to justify many trains.
If you accept that the paths through New Street are limited, I don't think we should be reducing the current half hourly Reading - Birmingham services (to accommodate some "direct to the south coast" services).
Whilst the current service isn't always competitive on time for long distance journeys from the south coast to the midlands/ beyond (compared to taking a fast train to Waterloo and changing for the ECML/ WCML or flying from Southampton up to Edinburgh etc), I don't think that avoiding Reading would speed the journey up by enough to make it competitive.