It will take at least 5 years to electrify/convert the valley lines, unless the network is completely shut down for a year or two, resulting in gridlock on Cardiff's roads in the meantime.
How long would it take if they closed it in sections? For example, close Queen Street - Radyr for x number of weeks/months while trains are diverted via Fairwater then the Fairwater route for a while etc. ?
'Priorities' like what? There will be no immediate solutions available to overcrowding and ageing trains next October, apart from the new franchise scraping together any spare 143/144/153s that no-one wants.
By next October, the London Overground 172s should be available. They wouldn't be able to enter service until December 2018 at the earliest I suppose because staff would need trainning but presumably the fitting of toilets can be done by October 2018 if the franchise is awarded in Jan/Feb 2018 and the winning bidder signs a lease deal immediately. The 8 class 172s could perhaps cover 6 diagrams, which would allow the franchisee to release 6 150s (two for PRM mods and four for the promised December 2018 Liverpool-Chester Halton curve service). It would also raise the quality of stock on the Cardiff-Cheltenham route, assuming that's where the 172s would be used.
I imagine unless EMT and LM get new self-powered trains, they'd like the above to replace their 153s and for extra capacity.
That depends on what stock the franchise ITT documents allow. My interpretation of the London Midland ITT is that no cascaded DMUs from other TOCs are allowed, only EMUs, locos, hauled stock and new units (which I expect could include 230s). We should find out soon with the winning bidder announcment for LM now due.
I wonder if the WAG will give bidders freedom to lease anything coming off-lease or if DfT will require a similar clause that the new W&B leaves DMUs available for EMT. Otherwise, given that award of W&B and EMT franchises now falls due around the same time (Jan/Feb 2018), we could have a suituation where both franchises are bidding to lease the same units.
22 x 185s will be made available in 2020 but to use those to replace non-compliant stock would require the SoS to grant an exemption order to keep the non-compliant in service longer.
if they secured the Scotrail 156s they could be introduced almost as soon as the franchise starts.
Are they similar enough to 150s and 153s that staff trainning would not be required?
PRM mods ready for 1/1/2020 will involve the entire Welsh 150/2 and 158 fleet being taken away in 2019 to be worked on. What will cover for the shortage of trains this will result in? Bear in mind nothing over 20m can operate on the Treherbert/Merthyr/Aberdare lines.
Mk3 sets are a good idea, but again, these will need power doors fitted.
It will be a challenging first few years for the new operator to say the least.
Thankfully the 158s probably don't require all that much work, given that BR built them with accessible toilets. Even then, 'challenging' could be an understatement if full compliance for the entire fleet by 1st Jan 2020 is insisted upon. Without a derrogation for the mark 3 fleet (until mark 4s or new-build long-distance units are available) and at least half the 150s the quality level of the franchise will fall considerably short of expectations. Unless power doors can be fitted to mark 3s really quicky, there is nothing of comparable quality available by 2020 unless a batch of mark 5s can be delivered in time (a now almost vanishingly small prospect). As for 150s, unless they are planning to electrify the ValleyLines at snails pace using only overnight clousures the franchise is eventually not going to have enough work for the full fleet of 36 units. A shorter lease on some of the 150s (allowing withdrawal once the wires are up) might only be acceptable to ROSCOs if they can get a derrogation to avoid the need for PRM mods.