Couple suggestions:
You may want to scale up your textures or build some new ones that are larger so that the repeating patterns aren't so prominent.
The maintenance pits probably shouldn't have walls that are sloping that much. I'm pretty sure they are just vertical so a drop shadow might serve you better than a bevel.

I think it is coming together swimmingly though, and will be watching its progress closely. When it is done, I'm likely to snag it for my own uses as well.