Stop a Moving Train! [WIP] & [C&C]

[TheChannel]

My next project I am working on is "Stopping a moving train"
I am trying to keep it in the Isometric style but I am failing at rounding out the corners and getting the right shading.
Note that there is no AA at the moment as I am trying to get the base down right now.

[Cyangmou]

Did a little and quick edit



the major problem is atm the wrong perspective of the roof and the stripe,  and there is also a lot of staircase banding in the whole piece.
You also used lots of colors, to much shades of gray. Try to make the whole thing with 5-6 shades of gray and about 3-4 shades of yellow. You won't need more.