There was an article some time ago in Railway Age
about the Panama Canal RR. Apparently, this uses
ex-Amtrak F40PH's to supply power to refrigerated
containers. For a variety of reasons, some
containers have to be removed from ships going
through the canal. The excess can go on the
Panama RR. This is/used to be owned by KCS.
Quite a lot of information about it is at
Wikipedia entry for Panama Canal
Paul.