The Bi-mode FLIRTs for Greater Anglia are, basically, an amalgamation of two British developments of the 1930s.
Many Argentinian railways were operated by British companies, including the Buenos Aires Great Southern Railway; round about 1930, it planned a staged process of electrification using EMUs powered by Mobile Power Houses built by Armstrong Whitworth in Newcastle. These did have some traction motors for independent propulsion, but power was also supplied to motors fitted to the EMUs; the power houses were single-ended, and semi-permanently coupled to the EMUs with which they worked.
Also in the 1930s, Walker Bros of Wigan developed the articulated power unit principle; this is probably best known for the single ended vehicles built for the County Donegal Railway in Ireland, but some double ended units were built for the GNR(I) - I think they were numbered D, E, F and G. These had a central power unit (again, I'm not sure, but I think D and E had six wheeled units and F and G had four wheeled ones), and un-powered driving saloons were articulated either side of the central powered unit. This was developed further after World War II, and Victorian Railways operated a fleet of what were known as Walker Railmotors; some were single cars (basically broad gauge versions of the Co Donegal ones), but some were double-ended 3-unit articulated sets, the centre car carrying two Gardner 8LW 140hp diesel engines, each one mounted above floor level.
So IF there is sufficient life left in the Mk III derived EMU sets to make it financially sensible, could they be used as a basis for some "new" bi-mode sets, using underframes from "Pacers" for intermediate vehicles carrying either diesel alternator sets or battery packs? These should be positioned within the train formation (say between vehicles 2 and 3), but if a single pack doesn't produce enough power, could a second be added and have them between vehicles 1 and 2 and 3 and 4? Would a 4-car set with two battery pack vehicles be able to operate the Buxton branch, for example?
The 'Renatus' re-builds have shown what can be done, but - bearing in mind the problems Brush have experienced with the class 769s - it might be best to do a complete renewal of the electric traction system using 3-phase drives; using intermediate generator/battery-pack vehicles, might something suitable for, say, the Windermere branch be produced using 317/319/321/322 EMUs as a base, with 455s being used to produce DC bi-modes to replace Southern's 'Turbostars'. Perhaps even a sexy front-end could be added to make the re-builds look "new" !
We must also remember that there are many newer vehicles soon coming off-lease, which already have air-conditioning; these include the 14 class 332 sets, which - with their rounded front-ends - already look "modern". Could these be rebuilt as bi-modes with intermediate 'Pacer' underframed-based battery-packs to operate services such as northern connect between Manchester Airport and Barrow/Windermere?
Discuss !!!!!