@goatsarah @cstross @danjac If you can fix some political issues (you have to go through either Russia or Iran), you could roughly halve the need for large container ships by building a high-capacity highly-automated electric freight line across Eurasia.
The back of my envelope says that five tracks in each direction between China (and the rest of East/SE Asia) and Europe would replace the entire container shipping traffic between the two, which is approx half of the world's container shipping.