I really liked all the photos I've seen. I wonder if you could group them in interesting ways - either as an exhibition with an order or as a book so photos on facing pages highlight a contrast, similarity or theme. You may be able to tease out some interesting observations doing this. One other thing, could you also change your angle of view? Perhaps by standing and having the camera hanging round your neck? This way you could have a view down the carriage rather than across which may give you some nice compositions.