I would agree with some of Susan's critique, albeit a bit differently. While there is something quite nice about the visual, I'm not sure what the message is.
I assume high-rise construction can be viewed as a solution to fighting low density sprawl, therefore saving land and resources. Cranes can also be viewed as a symbol of progress but I'm completely left guessing to what you're trying to say.
So, if you're going down the path I outlined in the paragraph above, I think your solution (high-density development) is much better identified then your pollution (sprawl). Support copy could solve the problem, or the pollution aspect of the poster can be better identified.
Good luck.
