Panama Canal Expansion Project

Due to be done in a few years, and for a while ahead of schedule (no longer at last check), this promises to save a bunch of carbon, and the new gates are more efficient water-wise than the old ones, allowing for less impact on the ecosystem of the Canal Zone, well less than would have happened with the same gate system as the old gates (100 years and ticking!).
http://en.wikipedia.org/wiki/Panama_Canal_expansion_project
the one knock against this, unless you get anarchistic, is that it could have been done with a railroad system, but that might have been even more destructive, as panama would have had to build a huge port on it's pacific side, plus a huge container yard, which might have been more of an eyesore and an environmental catastrophe than just this big construction project.