It's a great collection of shots, Erik and you're to be congratulated on an exciting project. My only concern would be that the very nature of a "captive audience" like this, all crammed into a carriage, can lend a certain sameness to the shots. For my money, it's all a bit static, not much happening. That has its own validity, of course - people don't tend to do cartwheels in a railway carriage - but for your exhibition/book you might want to maybe expand the theme a little to include, say, the activity on the platforms, with people struggling with luggage etc. You might also consider using several shots in a collage format. Great that you're considering an exhibition in Stockholm, but how about approaching the station authorities in Moscow or Kiev and setting up an exhibition inside the stations? That would really be a sharing with the people.
My two cents, for what it's worth. Keep on! Show us more!