Snow1964
Established Member
Part of the problem is UKs small loading gauge. There are plenty of standard designs like Alstom Corradia Stream where the design is proven with working software. But needs different body shell.Very interesting, though I wonder what the 52 station figure is (915mm tall platforms?), and a "sliding step gap filler" suggests low floor, presumably.
But what's most notable is how that seat count is really quite low - a 3 car 195 seats 204 and a 158 has 207. This is more akin to the very low density Class 197s or 170s.
The real problem is the units with a diesel generator as it's nigh on impossible to fit it under a low floor (technically it fits, but not if you want to also leave room to maintain it) hence the over floor power units that Stadler use. Sliding steps are an underfloor module that also needs space that isn't on older generation trains.
Of course if th space under the floor is used, an alternative is the roof. In Europe some equipment is roof mounted including HVAC units, yes can fit in slim units as roof can be lower if floor is low (and there are units like 350 / 450 with roof HVAC) , but still stuck with some equipment tending to be packaged at vehicle ends shortening usable floor space. So whilst a vehicle might be 23m long, the saloon might be metre or two shorter.