Yes they are too high, I'll rearrange them and mute the colours a bit more. Perhaps make them a tad smaller as well.
Heather I would hope that when the arches a built with a small amount of depth the carriages will look further away. I do like the idea of the letter box idea, I could have had them so that I could slide them in and out, particularly if they were DMUs. But I feel it is too late for that.