The page in my Subject Line may be of some interest here.
The section "Tehuantepec route" has something about a proposal to build a quadruple track ship-railway in the 1800's.
James B. Eads made the proposal.

When I saved the page in 2016 there was a illustration on the page showing how two locomotives would pull a ship across the isthmus
I didn't check to see if the current page still has the image, I hope it does 'cuz I believe railfans here would enjoy seeing the idea.
Ed
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