Tropical Construction Site

This photo is a bit of an exception to the theme of the blog: I'm not positive it is in the U.S. The countryside, as well as the style of building in the background suggests a more tropical environment. It could be Hawaii, but it also could be one of the Carribean islands, or Central or South America.
That being said, it's interesting anyway, as it shows what looks to be 1920s or 1930s construction techniques.

Given this site's elevation above the curving railroad track entering the picture from the far right, this well might be a loading facility of some sort. If you have a thought as to what they're building, please comment!

Sand, gravel and an early industrial-sized concrete mixer

The cars and trucks suggest the age of the photo