Why is bi-mode "costly and high-risk"?
I'd have thought that a hybrid EDMU would be ideal for this sort of work. There has been talk of fitting a pantograph to existing Voyager trains, which sounds like a really smart idea to me. If I was designing IEP, that's exactly what I'd be looking to create in a new train. So, can anyone tell me why it might not be such a good idea?
Basically, because of the amount of LDPE Diesel stock we have in the country at the moment, and the likely rate of electrification for LDPE routes, any additional Diesel LDPE Rolling Stock ordered now will likely be superfluous after the projects likely to be completed by 2025.
Midland Mainline
Edinburgh - Aberdeen
South Wales
TPE North
Combined with a 'Baby Pendo' Project this would release enough 22x and 18x rolling stock to over the routes currently worked by HSTs so these can be retired or cascaded to inter-reigonal diesel work by 2025.
Alternatively High Speed Two will be capable of releasing the ICWC Diesel Fleet by providing Diesel Haulable Classic Compatible stock for Holyhead and other Dieseley routes North of Rugley.
So, the useful like of any Diesel LDPE Stock that would be braught in around 2017/2018 would only be required until 2026, or would mean that the 22x fleet would be utterly useless after 2026 since use on Inter-Reigonal work for the 22x units aren't a good idea.
I have numbers to support this if you really really want to see them...
But basically, extending the life of HSTs out to 2026 combined with fitting power doors is a better and likely cheaper option than buying new, shortly to be useless rolling stock.
If any new Diesel or Electro-Diesel stock is to be ordered, it should be inter-reigonal stock for the retirement of pacers and reigonal route growth. There is no need for any Self Powered LDPE stock until the 22x fleet reaches retirement in 2035. By this point the electrification of the UK should be more extensive, and the Loco Hauled EMU sets as used on HS2 will be well proven so anything running past the limit of electrification will do so with a locomotive, say Exeter, Taunton or perhaps Plymouth by this point on the GW, and Inverness & Ft. William in Scotland.
Intermediate growth in EDMU Routes can be covered by electrification of the XC Network; namely...
Coventry / Birmingham International - Oxford
Reading - Bournemouth (New dual voltage EMUs for XC)
Bristol Parkway - Birmingham
Birmingham - Derby (Or using HS2 and Classic Compatible Stock)