It varies a bit. SBB and DB are standardising platform heights (SBB has mostly completed it, DB a bit lagging but well along the way), and at standardised stations there is indeed level boarding.As a matter of interest, what proportion of low-floor vehicles offer level boarding?
I ask, because my random experiences across Europe suggest many don't just much easier boarding than the traditional 3 steps up.
(Which takes me back beyond my first experience of mainland Europe to the London RF buses of my childhood trips to/from school... doubly OT, (not very) sorry!)
I think it'd be difficult in UK loading gauge. But it needn't be a separate vehicle a la Stadler, it could just be a short end section of one of the main coaches with a counterbalance ballast at the other end.I wonder if you could do roof mounted, the MTU engines used the civitys are advertised so that they can be mounted on the roof which could allow for level boarding without the need for the generator car in the FLIRTs.