Gulp: A fully loaded neo-Panamax ship is rated to carry 120,000 tons DWT (which excludes the weight of the ship itself). A train composed of heavy-axle rail cars has an upper limit of about 160 tons. Building bridges and a rail bed to carry a load 1,000 times larger than ever before is no small thing. Then you need to build drydocks to get a fully-loaded ship on and off a train. Building rail cars that would hold the thing ... I wonder if it's even possible in metallurgical terms ... I seriously doubt a rail-car wheel could carry 1,000 times as much load as it does currently.
Apparently some Australian ore trains are 43,000 tonnes (24000 tonnes of ore), according to Wikipedia (https://en.m.wikipedia.org/wiki/Longest_trains) so we are within an order of magnitude
Canales origionly used mules to pull the boats. that today would avoid the props on ship digging up the bottom. Those land based trains can also be electric for environmental savings.
In the Panama Canal ships are pulled by locomotives on rails next to the canal. They have to do that because the canal is too narrow for ships to steer under their own power
