This really great post card shows the magnitude of the project.  This scene is not doubt out in the soon to be flooded Gatun Lake area.  The culvert would eventually allow water to flow from one side of the filled in causeway to the other.  By looking at the length of the culvert, you can get an idea of how much fill will be dumped on top of it.  The trestle is probably at the 87 foot above sea-level elevation and will eventually be buried in fill dirt to make the new rail line bed.  This particular post card inspired me to do this presentation.