Hi,
As for your design Ill keep an open mind as to how it'll work. I can see why it seems like a good idea but I have reservations as to how practical it'd be in terms of access and hence loading (dwell) times,. I look forward to seeing your ideas though...
I'd like to speculate on the design from what you've said so far. I don't expect a response but it's fun to think...
So, it's an articulated double, with a mid-level loading / unloading middle platform height area at each end of the pair. The articulated bit is bi-level, with carefully offset walkways to allow extra headroom.
Downstairs will have an offset corridor and bays of 4 seats a side with lower headroom.
I'd guess the windows would actually allign with the seats!
Upsatairs will have a walkway of the opposite side (above the downstairs seats).
There'd again be bays of 4 seats a side but you'd probably have to step up to the floor level of these plus the headroom would be a bit limited.
The windows would allign with the seats and would wrap around from the sides onto the roof. That'd give extra light and a sense of space.
The space betweem the offset corridors (in the middle of the coach) could be used for services such as AC ducting and power. It would be a gently tapering box to give the impression of space rather than a square duct. All lighting would be slimline and take little room.
With the use of modern materials, I can see how something like my speculation could be built.
However, and this is biggie:
To get anything like this ordered you've got to get past the EU tendering stage. There's a reason Siemens, Bombardier & Alstom win. They have a) large teams with much experience of writing tenders and b) they know it's a very long game and one where you need to know the right people.
If you're a sole inventor or small company you will need to partner with a big player to have any credibility at the tender stage.
That does all sound negative but if you can see a way forward then I wish you every success.
Cheers!
Jason